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HVAC stands for Heating Ventilation and Air Conditioning.

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Benefits of implementing HVAC systems into building development

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Benefits of implementing HVAC systems into building development

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1) Save money in utilities
2) Improved Air humidity and health benefits
3) Limits exposure to extreme temperatures
4) Better air quality
5) Less airborne pollutants

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1. Equipment rooms: since the total mechanical and electrical space requirements range between 4 and 9% of the gross building area. It is preferable to be centrally located in the building to reduce the long duct, pipe, and conduit runs and sizes, to simplify shaft layouts, and centralized maintenance and operation.

2. HVAC Facilities: The design of equipment rooms to host both pieces of equipment should consider the size and the weight of equipment, the installation and maintenance of equipment, and the applicable regulations to combustion air and ventilation air criteria.

3. Vertical shaft: provide space for air distribution and water and steam pipe distribution. The air distribution contains HVAC supply air, exhaust air, and return air ductwork. Pipe distribution includes hot water, chilled water, condenser water, and steam supply, and condenser return. The vertical shaft includes other mechanical and electrical distribution to serve the entire building including plumbing pipes, fire protection pipes, and electric conduits/closets.

4. Equipment access: the equipment room must allow the movement of large, heavy equipment during the installation, replacement, and maintenance.

Reference 3)

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Chilled water is produced via a centralised plant and then circulated to services throughout the building.

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Installed chiller onto an existing chilled water system supplying pressure test rigs

https://www.klimatec.co.uk/case-study-4

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High requirements for water quality

High Maintenance costs

Large weight index

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These systems deliver a constant volume of conditioned air from the AHU. They are not suited to multi-zoned buildings with varying cooling requirements, therefore they are generally used in single zones, such as a central foyer or as part of a cooling system with the primary cooling being achieved by other means, such as FCUs.

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A 60,000-sq-ft government administration building constructed during the mid-1950s, comprised of a basement and four floors, had two constant volume multi-zone dual-duct (MZ-DD) air handling units (AHUs) to provide both cooling and heating. The AHUs were located in separate mechanical rooms, one in the basement while the other was on the top floor. (Schrecengost, R,. 2019)

https://www.csemag.com/articles/case-study-flexible-reliable-hvac-system/

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Case study: Flexible, reliable HVAC system | Consulting - Specifying Engineer

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A 60,000-sq-ft government administration building constructed during the mid-1950s, comprised of a basement and four floors, had two constant volume | Consulting - Specifying Engineer

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supply air temperature is varied, but, the volume flow rate (supply) of air is constant.

https://theengineeringmindset.com/constant-air-volume-cav/

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Constant Air Volume, CAV. In this article, we're going to be looking at the CAV system. CAV stands from Constant Air Volume. CAV is a means of delivering conditioned air around a building. It's becoming less common in new buildings simply because VAV, Variable Air Volume, systems are replacing them due to their superior zone control and much reduced energy consumption.
Scroll to the bottom to watch the YouTube tutorial on CAV systems.
Although Constant Air Volume systems are becoming less common in new buildings, you might still find them in smaller buildings; especially older ones. The reason you'll find them in smaller buildings is because they're fairly cheap to install and they're much simpler to install and operate. Additionally hospitals will often still use these systems for their theatres.

Looking at a CAV system, we have a simple model of a small office below.

We have the AHU, Air Handling Unit, which is located within the plant room on the left side. Then we have the supply duct, which is taking all the fresh treated air from the AHU and delivering this throughout the building. The treated supply air exits the duct into the rooms via the diffusers. It circulates around the room and the used dirty air is then sucked into the return dict via a grille somewhere else in the room. This air will be returned back to the AHU where it can either be dispersed straight out to atmosphere or some of it can be recycled and reused.

Now, in this video, we're not going to be looking inside the AHU to see the components as we have already covered this in other videos. If that is of interest to you, then I highly recommend you check out our "Fundamentals of HVAC" where we cover this in great detail.

CAV systems do have some limitations because the supply air temperature is varied, but, the volume flow rate (supply) of air is constant.

While the system runs, it provides air at a consistent and constant volume and only the temperature of that air changes. Typically, the air is provided at around 13 degrees Celsius, (55 degrees Fahrenheit), but this can be adjusted to suit the needs of the building. Now, as I said, the volume is constant but the amount of air which it provides is really going to depend on the size of the area that needs conditioning. The activity's occurring within the rooms will dictate how much air needs to be delivered to a room.

To give you an idea though, the small room in the middle of the previous illustration, might require something like 3 cubic meters per second. However, the larger rooms on either side might require somewhere around 20 or 30 cubic meters per second. It could be that the entire building only requires 30 cubic meters per second as well. But it can be a lot more than this. Say we have a 40 story building with just one enormous AHU on the roof, then that's going need to supply an extremely large volume of air per second.

One of the problems with the CAV system, is that everything connected to this AHU is classed as one zone, and that means all the rooms connected to it receive the same temperature air regardless of their heat load. So, if one room was a busy meeting room in the middle of summer which is full of people, it's going to be generating a lot of heat. It also has solar thermal gain too. But with a CAV system, that room will receive the same air temperature as the empty room next to it. This means the zones are given a set amount of cooling regardless of their requirements. This is not efficient because it's going to be wasting a lot of cooling energy, generating and providing cooling for no reason.

The fans would also run at 100% the entire time the system is running. Although you could fit some VSD/VFD Variable Speed Drives / Variable Frequency Drives, to reduce the motor speed.

It's very difficult, but not impossible, to convert a CAV into a VAV system. It's going to take a lot of time and effort. You have to change a lot of things and modify a lot of the controls for it. The conversion can unlock a lot of energy savings although a CAV is cheaper to install and easy to operate.

From this schematical representation of the CAV system, you can see how it's connected. Notice that all of the rooms are connected to the main duct, and the only form of temperature control is in the main AHU. That means that all the rooms receive the same tempered air at a constant volume.

The CAV design will work very well if all the rooms are of a similar condition or require a similar cooling/heating condition. But if a room has a different cooling/heating load, then it might need to be connected to a different AHU. Depending on the size, it might be better with it's own AHU supply.

One way around this is to install terminal re-heaters. These are usually found in a metal box in the ceiling, before the diffuser. Typically these are electrical heaters. They could also be from the hot water system. These will reheat the air up to a higher temperature, but obviously that is very energy inefficient because you're already cooling the air down in the AHU and now you're paying again to heat that air back up. So, you're wasting money on the cooling and then also on the heating.

Typically, the air temperature for this type of system is supplied at the coldest temperature possible and that suits the room with the largest cooling load. Looking at the illustration, the largest room will likely have the biggest cooling load but the other rooms will have the reheater installed.

Another option you might see out in industry is the dual duct CAV system.

It's becoming increasingly uncommon to see this, you could still find it in some older buildings though. But basically, you have two ducts running and supplying the room, and one of these will be providing cold air and the other duct will be supplying warm air. This air is then mixed by some dampers in a box at each room just to suit the temperature inside. That return air is then also returned back to the AHU, ready to be recycled or dispersed out to atmosphere.

This system gives a much improved thermal control but there is little control of humidity. Again, it's not particularly energy efficient either. As you're supplying air through two streams, you have a lot of resistance which the fan is going to have to overcome. You're also unnecessarily heating and cooling air which might be mixed.

To make the dual duct system more energy efficient, then you should ensure that a temperature reset is enabled on controls. You will need a few advanced control points in there and some temperature measurement sensors. The temperature reset controls will monitor the air conditions which are required, and then reduce the air temperature of the hot air to bring that temperature down to the lowest acceptable temperature. The controls will also raise the temperature of the cold air temperature to reduce the cooling load provided by the coil.

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Constant Air Volume - CAV - The Engineering Mindset

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Constant Air Volume, CAV. In this article, we're going to be looking at the CAV system. CAV stands from Constant Air Volume. CAV is a means of delivering conditioned air around a building. It's becoming less common in new buildings simply because VAV, Variable Air Volume, systems are replacing them due to their superior zone [...]

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The system is split into an outdoor heat rejection unit and an indoor room cooling unit. The refrigerant is pumped directly between the units and operates with 2-pipe connections.

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Case Study (Fujitsu Ductless HVAC Installation Portsmouth, NH)

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Case Study (Fujitsu Ductless HVAC Installation Portsmouth, NH)

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Problem: The Dinsmore family wasn’t satisfied with the heating and air conditioning solution for the second floor of their home. They decided it was time to fix this problem once and for all before the next summer rolled around.

Solution: The homeowner contacted Townsend Energy and asked for a consultation. We sent our HVAC specialist Mike Mondalto to the property to consult with the owners while assessing the situation. He recommended installing a Fujitsu ductless mini-split system.

https://www.townsendtotalenergy.com/case-studies/ductless-installation-portsmouth-nh

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Springtime is right around the corner, and before long summer will be here. The Dinsmore family recognized this inevitability and decided that it was time to cool the second floor of their house properly with a ductless mini-split system.

Until now, they had energy-inefficient outdated air conditioners cooling their home. As we all know, the old window units aren't nearly as effective as a ductless mini-split system. So, it was time for the Dinsmore clan to make a change.

Most people do not consider Portsmouth, NH the hottest or most humid place in the world. But it gets hot enough during the summertime and nobody would want to spend their days cooped up indoors without proper air conditioning. Let's not forget about the amazing heat delivered to each his own during the winter as well.

In the end, the Dinsmore family contacted Townsend Energy and let us know about the second floor of their home. Our expert tech Mike Mondalto visited the property and took a close look at the second floor. He recommended a mini-split system with a Fujitsu heat pump and air-conditioning and three wall-mounted evaporators for the second floor. Keep reading to explore this ductless mini-split installation Portsmouth NH.

Problem: The Dinsmore family wasn't satisfied with the heating and air conditioning solution for the second floor of their home. They decided it was time to fix this problem once and for all before the next summer rolled around.

Solution: The homeowner contacted Townsend Energy and asked for a consultation. We sent our HVAC specialist Mike Mondalto to the property to consult with the owners while assessing the situation. He recommended installing a Fujitsu ductless mini-split system.

Fujitsu Ductless Mini Split System In Portsmouth NH: Overview

Up to 23 SEER Rating: The level of energy consumed based on this rating means that this is a highly energy-efficient model. This helps lower energy costs because the unit consumes less power, yet comfort remains intact without sacrifice.

10-12-year Limited Warranty: Fujitsu takes pride in providing 10-12-year limited warranties on parts and compressors. This warranty is only valid if the product registration is submitted and it's installed by an Elite Contractor.

Inverter Technology: This heating and air conditioning system comes equipped with inverter technology, which permits the heat pump to cool or heat the room based on room temperature and other conditions. The system determines the air quality and temperature via a sample and makes necessary compressor speed adjustments to deliver a consistent and smooth temperature while lowering energy costs.

Quiet Operation: Unlike the old window units, a Fujitsu mini-split system operates in a quiet capacity. It emits so little volume that it's hard to tell when the system is turned on because it's so quiet.

Humidity Control: Spending time in a home overcome by humidity is warm, sticky, and uncomfortable. The humidity control system makes it possible to lower the levels of humidity in each zone, making it very comfortable for the occupants.

Wireless Remote Control: A wireless remote control is ideal because it allows the occupant to control the Fujitsu ductless mini-split system from anywhere in the home. It's convenient, easy to use, and makes it possible to adjust the temperature while sitting on the couch, lying in bed, or eating dinner at the kitchen table.

When To Consider Installing A Ductless Mini Split System In Portsmouth New Hampshire

The Dinsmore family had a situation that was far from unique for homeowners with two-story homes. Unfortunately, these homes tend to have uneven temperature differences between the upstairs and downstairs portions of the residence.

In fact, many upstairs bedrooms tend to be much hotter than the rooms in the downstairs portion of the home. This naturally causes the homeowner to lower the temperature on their central air-conditioner thermostat to make the upstairs rooms feel cool and comfortable.

This also leads to extra energy consumption, higher energy expenses, and uneven comfort levels when comparing the upstairs and downstairs of the home. The upstairs rooms eventually become cool after lowering the thermostat temperature, but the downstairs rooms become unnecessarily cold due to the lowered temperatures.

A Solution To Uneven Temperatures In Portsmouth Homes

Expert technician Mike Mondalto from Townsend Energy recommended a ductless mini-split system for this very reason. He knew that a ductless mini-split system was the superior choice in this situation because the occupant has full control of each wall mount unit per zone.

As an example, let's say the technician sets up three zones on the second floor of the house. The first zone is in one of the bedrooms. The second zone is in the other bedroom. And the third zone is in a room designated as an office.

The homeowner prefers to keep the office on the colder side while working. He can adjust the air temperature on his own to keep it cooler than other rooms on the second floor. The bedrooms can keep the temperature higher so it isn't as cold, without forcing the office to maintain the same temperature as the bedrooms.

A ductless mini-split system is perfect for families who prefer varying temperatures to meet their preferred levels of comfort. In some homes, one person tends to feel hotter than the rest, and that person often suffers needlessly in a situation when a traditional central air conditioner is the only option.

Additional Benefits Of Ductless Mini Split Systems For Portsmouth Homes

Besides the ability to adjust comfort levels in a room or zone, ductless mini-split systems have other great benefits that homeowners love and appreciate. Those benefits include the following:

High Efficiency

This point needs to be emphasized over and over again. The inverter technology within a ductless mini-split system works diligently to maintain the preferred temperature within a room. This is important because the inverter causes the mini-split system to use the least amount of energy possible while keeping everyone comfortable according to their preferences. This also makes it easy for homeowners to save money every month.

Different Styles

In the case of the Dinsmore family, they chose to go with a wall-mounted mini-split system. But other options are available.

There are concealed duct mini splits, which received their name because they are perfectly concealed inside the wall. In this case, a small amount of ductwork is needed, but it makes it possible to provide an air outlet into the room while keeping the mini-split perfectly concealed.

Ceiling cassette units are another possibility. These units hide the heat exchanging parts within the ceiling. Some homeowners prefer this option because it removes the obtrusive parts and keeps them hidden from view.

No Need For Ductwork

With a ductless mini-split system, there is no need for an expert technician to install a system of ducks within the home. This is positive because more often than not, central air conditioners require ductwork maintenance. This is time-consuming, often irritating, and the ductless system is much easier for the homeowner to maintain and causes far fewer headaches.

By eliminating the ducts from a mini-split system, the homeowner can place their air handlers in any area that requires heating and air-conditioning. This leads to much less maintenance than traditional central air-conditioning units.

Fujitsu Ductless Mini Split System Upgrade Considerations

HVAC Warranty: Fujitsu really stands by its products. They offer tremendous 10-12-year warranties for parts and the compressor. To qualify, homeowners must submit their warranty and have the system installed by a licensed contractor.

Heating & Cooling Brand Reputation: The name Fujitsu is synonymous with creating and developing high-quality ductless mini-split systems and parts. It's a trustworthy company with a phenomenal reputation in the industry.

HVAC Equipment Lifespan: It's always better to choose a product with a long lifespan whenever possible. This means the homeowner will get longer and better use of their money. Fujitsu products are known to last for a long time.

Heating & Air Conditioning Contractor: Townsend Energy is a well-known and well-respected HVAC contractor in Portsmouth, NH, and the surrounding area. We take great pride in helping this community meet their heating and air-conditioning needs.

Conclusion

If you're in need of an AC compressor upgrade, repair, replacement, or service in Dover, NH, you must contact Townsend Energy right away. We provide the fastest and most reliable service in the area and we work hard to live up to these claims.

Call Townsend Energy For Superior Home Comfort Solutions

Townsend Energy is a full-service HVAC company that services residential and commercial properties throughout New England. We offer a range of heating and cooling services, including HVAC installations, repairs, tune-ups, and more.

Our experienced, HVAC-certified professionals can find the best home heating and cooling solutions for your home while working with your budget. We aim to improve your home's level of energy efficiency, comfort, and indoor air quality. Our work is backed by a warranty to ensure your satisfaction. We also provide free, in-home estimates. Call Townsend Energy today.

Click here to contact us now or you can call us at (800) 888-2888 to find out more!

Check Out Our Reviews In Portsmouth NH:

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Fujitsu Ductless HVAC Installation Portsmouth, NH - Townsend Energy

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CASE STUDY* View A Ductless Mini-Split Installation Project For A Portsmouth NH Home By Townsend Energy. Click Here For Details.

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Require sufficient wall space (space limitations)

Require regular maintenance

Installation cost (professional installation & cost of split system asset)

https://www.linkedin.com/pulse/pros-cons-split-ac-cool-comfort-chilling/

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FCUs that use refrigerant will often have 3-pipe connections (hot and cold flow and a single return) allowing for simultaneous heating and cooling to separate zones. Some systems achieve simultaneous heating and cooling with only 2-pipes (flow and return) where the flow pipe contains refrigerant in both vapour (for heating) and liquid (for cooling) form.

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GTI conducted a side-by-side demonstration of two VRF heat pump technologies that offer significant potential for energy and cost savings, as well as improved comfort with zoned temperature control.

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High probability of leaks (Vicinity)

Maintenance costs

Initial cost

Integration with other systems

https://www.airtest.com/post/the-pros-and-cons-of-vrf-systems

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Variable Refrigerant Flow Systems: A Balanced Look at the Pros and Cons

As building managers, property owners, and facility operators, it is essential to stay informed about the latest HVAC technologies to optimize your building's performance. In this article, we will discuss Variable Refrigerant Flow (VRF) systems, an increasingly popular HVAC technology offering both heating and cooling solutions for various types of properties, such as shopping centers, universities, hotels, and large commercial buildings. We will examine the advantages and disadvantages of VRF systems to help you determine if they are the right choice for your building.

Pros of Variable Refrigerant Flow (VRF) Systems:

1. Energy Efficiency: VRF systems are known for their energy-efficient operation. They modulate the flow of refrigerant according to the specific needs of each zone, reducing energy consumption and lowering utility costs.

2. Flexibility: VRF systems provide exceptional design flexibility. They can accommodate a wide range of building sizes, layouts, and architectural constraints, making them suitable for both new constructions and retrofit projects.

3. Comfort: VRF systems deliver personalized comfort for occupants by independently controlling the temperature in each zone. This allows for customized climate settings based on individual preferences and usage patterns.

4. Simultaneous Heating and Cooling: Some VRF systems can simultaneously provide heating and cooling to different zones within a building, further enhancing energy efficiency and occupant comfort.

5. Quiet Operation: VRF systems are known for their quiet performance, which can be particularly beneficial in noise-sensitive environments such as hotels, offices, and educational institutions.

Cons of Variable Refrigerant Flow (VRF) Systems:

1. Initial Cost: VRF systems can be more expensive to install than traditional HVAC systems due to their complexity and the need for specialized components.

2. Maintenance: Maintaining a VRF system may require specialized knowledge and training, which can be an additional cost for building operators. Some components, such as the refrigerant piping network, can be challenging to access for maintenance and repairs.

3. Refrigerant Leaks: VRF systems use refrigerant as the heat exchange medium, which can pose potential risks if leaks occur. Leaks can result in decreased efficiency, higher energy costs, and potential environmental and safety concerns.

4. Integration with Other Systems: Integrating VRF systems with other building systems, such as building management systems (BMS) or energy management systems (EMS), can be complicated and may require additional customization.

Variable Refrigerant Flow systems offer several advantages, including energy efficiency, flexibility, and personalized comfort. However, they also come with some drawbacks, such as higher initial costs, maintenance challenges, and potential risks related to refrigerant leaks. When considering a VRF system for your building, it is essential to weigh the pros and cons to make an informed decision that aligns with your property's unique needs and goals. By keeping the needs of your target market in mind, such as large property owners, building operators, and facility managers, you can make the right choice to optimize your building's performance and ensure the satisfaction of its occupants.

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Ollie is a vast library of over 100 interface blocks with complete Webflow CMS integration. Build beautiful websites in less time than ever.

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Active chilled beams operate in the same principle as the passive with the exception of having fresh air ducted to it. Rather than air being drawn into the beam by buoyancy it is induced by the ducted air.

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Renovation of an Induction System with Active Chilled Beams

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High initial cost

Lower cooling capacity

large coil surface area required.

https://www.linkedin.com/pulse/exploring-efficacy-efficiency-chilled-beam-technology-modern-hvac/

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Long rectangular units located at high level circulate chilled water in finned pipes and exchange coolth. Convection occurs with warm rising air being cooled by the chilled beams.

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CHILLED BEAM ENERGY STUDY

www.feta.co.uk/associations/hevac/specialist-groups/chilled-beams--ceiling-association.

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High installation Cost

Dehumidification can be energy intensive

Limited ceiling space requirements.

https://www.betterbuildingspartnership.com.au/information/passive-chilled-beams/

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Regulating dampers direct the air flow to either the heating or the cooling exchanger coil.

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A cooling tower is more efficient than a dry air cooler because it uses evaporated water to assist the rejection of unwanted heat but requires greater maintenance.

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Warm water is piped across fans within the dry air coolers forcing the temperature of the water to drop.

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Plant equipment to produce chilled water. Heat is removed from an unwanted area and rejected externally. Packaged chillers include heat rejection as part of the unit. Other chillers require dedicated heat rejection plants, such as dry air coolers and cooling towers.

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A fan blows air across a heat exchanger coil that will contain hot or cold water (or refrigerant for VRF/VRV systems).

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The fan-coil unit can be placed in the room or exposed to occupants, so it is essential to have appropriate finishes and styling. For central systems, the fan-coil units are connected to boilers to produce heating and to water chillers to produce cooling to the conditioned space. The desired temperature of a zone is detected by a thermostat which controls the water flow to the fan-coil units.

Reference 4)

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AHUs maintain adequate ventilation by providing fresh, filtered outside air and delivering it at the condition required to the internal space. AHUs can be used to control the temperature and humidity of the air.

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Air is supplied from the AHU at a constant temperature to a number of VAV units, each with a damper which controls the flow of air through it depending on the cooling or heating loads.

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Some spaces require different airflow of supply air due to the changes in thermal loads. Therefore, a variable-air-volume (VAV) all-air system is the suitable solution for achieving thermal comfort.

The VAV system consists of a central air handling unit which provides supply air to the VAV terminal control box that located in each zone to adjust the supply air volume

Reference 4)

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2-pipe FCUs have only one coil so they can only provide heating or cooling at any one time. Their mode can be changed on a seasonal basis as required.

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Variable Refrigerant Flow (VRF) and Variable Refrigeration Volume (VRV) systems circulate refrigerant like a split system but have multiple indoor units providing simultaneous heating and cooling. They can operate with a 2- or 3-pipe connection.

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4-pipe FCUs have dedicated coils for heating and cooling and thus four pipe connections (hot and cold flow and returns).

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A single zone system consists of an air handling unit, a heat source and cooling source, distribution ductwork, and appropriate delivery devices. The air handling units can be wholly integrated where heat and cooling sources are available or separate where heat and cooling source are detached.

Reference 4)

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The dual duct all-air system is a terminal-controlled modification of the multi-zone concept. A central air handling unit provides two conditioned air streams such as a cold deck and a hot deck

Reference 4)

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1) ASHRAE Handbook. HVAC Systems and Equipment. Atlanta, GA: American Society of Heating, Refrigerating, and Air Conditioning Engineers; 1996. pp. 1-10

2) American Society of Heating, Refrigerating & Air-Conditioning Engineers. ASHRAE Handbook. Fundamentals: SI ed. Amer Society of Heating, Atlanta, GA; 2009

3) Haines RW, Myers ME. HVAC Systems Design Handbook. McGraw-Hill Education; 2010

4) ASHRAE Handbook. Fundamentals. Atlanta: American Society of Heating, Refrigerating and Air Conditioning Engineers; 2001. p. 111

5)

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Highline 260i Airside Fan Coil Unit

https://www.keaneenvironmental.ie/wp-content/uploads/2015/10/Highline-260i-Airside-Literature.pdf

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Space requirements (especially vertically)

https://www.evomart.co.uk/vol-52-airside-waterside-control-fan-coil-units-continued/

Limited ability to deal with added air resistance

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In last month's article (VOL 51) we looked at the Airside control Fan Coil Unit based system

We now continue in more detail with these important criteria in mind in our coverage of this increasingly popular and important approach to comfort conditioning.
Airside/Waterside Control Fan Coil Units
In last months article we briefly explained the operation of Airside control fan coil units. In this months article we tackle Waterside control, as well as the advantages and disadvantages of Airside over Waterside control fan coil units.

The following stages describe and illustrate the cooling, bypass (ventilation only) and heating operations of Waterside control more clearly:
Heating Mode:
Waterside - Cooling valve in bypass mode, Heating valve in the open / control mode thus allowing low-pressure hot water to pass through the heating coil and affect heating.
Bypass Mode:
Waterside - Both cooling and Heating valves in their bypass positions. Therefore neither coil is in circulation.
Cooling Mode:
Waterside - Cooling valve in open / control mode thereby allowing Chilled water to pass through the cooling coil and affect cooling. Heating valve in bypass mode,

Comparison of Advantages and Disadvantages

When compared to its' Waterside counterpart, Airside control fan coil equipment is claimed to be more efficient. This is due to the Airside control fan coil equipment being more effective in its thermal control operation because the unit maintains the space condition by mixing quantities of heated or cooled air with a proportion of re-circulated air. As stated earlier, the controls can respond very quickly and accurately to changes in space temperature.

Waterside control units, on the other hand, are less responsive due to the fact that they rely on the control, to valve, response time. The unit output not only being related to the temperature of the space but also the condition and rate of the chilled water subsequently being supplied (following valve initiation), thereby, possibly operating with a certain degree of lag. For instance, when a waterside unit changes over from Heating to Cooling, the unit has to dissipate all the heat remaining in the Heating Coil before it can commence the Cooling operation (and vice versa for the changeover from Cooling to Heating).

Airside control fan coil equipment is also potentially easier to install and commission. With this type of system the water flow is allowed to circulate relatively unrestricted with the airside mechanism, factory pre set, operating and modulating to maintain the space temperature. This is contrary to the Waterside system that requires proper and accurate balancing in order for the 4 port valves to control the system correctly

Airside control systems shouldn't suffer from a water-related problem. Waterside control units utilise a valve to control the flow of water through a small clearance section within the valve. This section can be prone to blockage or sticking, when the water system concerned has not been thoroughly and frequently maintained, there by rendering the system or unit out of design parameters.

The Airside control system has no requirement for 4 port valves. This means that the overall system has a reduced resistance requirement, which in turn gives savings on the pump or pumps due to a lower duty being necessary.

It is simple to use, service and maintain and can be manually set up should the electrically operated controls fail.

Airside control systems have, of late, been the subject of various in-depth investigations and reviews with regard to net performance. Prospective users of this type of system must ensure that they have been soundly advised on the available capacity within the space to be conditioned.

However, Airside control systems can, in some instances, be unsuitable in certain applications due to physical space restrictions. Unfortunately, because of the area required to occupy and operate the damper mechanism, the unit can be larger than usual, particularly with the vertical style unit, and this may prohibit it's use for instance under a particular sill height.

Summary

Like all forms of heating, ventilation and air-conditioning equipment used in today's building services environment, the Airside Control Fan Coil Unit has its place for applications within the range of solutions for heating and cooling problems.

As can be seen from the above descriptive passages, this type of equipment can offer benefits in both the initial capital cost of design, application, installation and the ongoing expenditure relative to efficiencies in some areas. However, it can lose out in not being able to fit some installation situations and the efficiency can be called into question if the initial equipment design hasn't been 100% or the net output hasn't been clearly stated and taken into consideration.
DISCLAIMER:
Whilst every effort is made to ensure absolute accuracy, Business Edge Ltd. will not accept any responsibility or liability for direct or indirect losses arising from the use of the data contained in this series of articles.

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VOL 52 - Airside/Waterside Control Fan Coil Units (continued) Evomart

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VOL 52 - Airside/Waterside Control Fan Coil Units - Waterside counterpart, Airside control fan coil equipment is claimed to be more efficient.

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https://blog.amg-eng.com/cooling-tower-capacity-case-study

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BACKGROUND:

Our company was hired to figure out if this client's existing cooling tower was big enough to support their planned expansion. When we design a new plant that requires the use of cooling towers, we normally have access to the information of the process equipment that the cooling tower water system will be servicing, so a quick energy balance is developed to predict the size of the cooling tower.

The plant's location, elevation, and seasonal demand are critical elements to consider when selecting the size and type of cooling tower to specify and quote. It is customary to slightly overestimate the size of cooling tower needed, to allow for future equipment additions that may have been overlooked during the original evaluation.

THE PROBLEM:

On the other hand, when an established facility decides it's time to expand, it's much more difficult to define whether their current cooling tower will support the expansion. This is a challenging effort because our first task is to investigate how the system was modified over the years, and then measure how the cooling tower is performing under the current conditions. This helps us decide if we can add heat load, or if an additional cooling tower will be needed.

THE SOLUTION:

We began with a quick survey of the cooling tower P&IDs to document all the existing pieces of process equipment that were being serviced. Needless to say, many pieces of equipment were added over the years, but never recorded on the P&IDs.

None of the main headers or branches had flow meters, so predicting the flows was difficult, and we had to find a way to measure and calculate the flows for each branch. Some of the existing temperature gauges were providing inaccurate temperatures, so we had to establish a protocol to take temperature readings for the overall system.

The cooling tower water pump curves, plus amperage readings gave us an idea of the overall "supply" flow rate. However, to figure out the current heat load, we needed to know flows and temperatures for all the "return" branches.

Once the current heat load was defined, we proceeded to add the loads for the new equipment. We performed analysis for summer and winter conditions, to make sure that the existing cooling tower was big enough or if additional capacity was needed.

Our conclusion was that the immediate additional heat load resulted in a 25% increment, so the existing cooling tower, pumps, and piping were unable to handle the incremental load, and a new cooling tower had to be added. When we sized the new cooling tower, pumps, and cooling tower water headers, we had to include the heat load for the potential expansion in the next five years.

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Discover how we helped a client determine whether their current cooling tower was big enough to support their planned expansion in this case study.

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Only effective for large quantities of utility water

Sensitive to climatic changes

Physical appearance may be negative in the public eye

High cost of utility water

Potential growth of Legionella

https://encyclopedia.che.engin.umich.edu/cooling-towers/

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https://www.icscoolenergy.com/case-study/dry-air-cooler-fails/#

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Cons:

Cannot cool the process water below dry bulb temperature (without adiabatic pre-cooling);

Relatively low capacity per unit.

https://www.kaltra.com/single-post/2019/08/19/dry-coolers-vs-wet-cooling-towers#:~:text=No%20water%20loss.-,Cons%3A,Relatively%20low%20capacity%20per%20unit.

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Working Principle

Cooling towers are heat-transfer devices that are used to reject heat loads to the atmosphere. Cooling towers are used to cool circulating water in a wide variety of applications such as process cooling and HVAC systems.

Cooling towers extract heat to the atmosphere through the cooling of a water stream to a lower temperature. There are two main types of cooling towers:

Open-circuit cooling towers (also referred to as wet cooling towers), where process water directly contacts with the ambient air;

Closed-circuit cooling towers, or dry coolers, involve no direct contact between the ambient air and the fluid being cooled.

Both types serve the same purpose but cool the water in different ways.

Wet cooling tower relies on the latent heat of water evaporation to exchange heat with the air stream passing through it, and able to bring the process water temperature down below the ambient temperature to a certain degree above the dew point (approach temperature). Opposed to it, dry cooler only brings the water temperature down to the ambient, but additional cooling can be achieved by adiabatic pre-cooling of the inlet air. Wet cooling towers work efficiently in hot and dry climates, but as the ambient air becomes humid, the performance of wet cooling towers fall. Conversely, dry cooler performance is not affected by air humidity but relies on the air temperature.

System Design

Dry Coolers

Dry coolers feature a straightforward and robust design which includes a heat exchanger (typically finned tube or microchannel coils) and fans which direct the airstream through the heat exchanger to cool the water or glycol solution passed through it. Dry coolers are mostly available in horizontal or vertical airflow arrangement. Heat rejection capacity typically ranges up to 1MW, although large-capacity dry coolers are also available on the market.

Modern designs may include pre-cooling systems, either adiabatic spray or wetted pads. Evaporative pre-cooling allows cooling the process fluid below dry bulb temperature.

Wet Cooling Towers

The structure of a wet cooling tower is way more sophisticated. It includes nozzles to spray hot water homogeneously onto the heat exchanging media (also referred to as fill or wet deck), fans which direct ambient air throughout the cooling tower, drift eliminators which prevent water droplets from discharging with the air, and collection basin for the cooled water. The air flows from the bottom of the tower (counterflow-type tower) or perpendicular to the direction of water flow (crossflow-type tower).

The most common types of heat exchanging media are film fill and splash fill. Film fill is a set of textured sheets with the large surface area on which the water spreads and forms a thin film in contact with the airflow. This guarantees a high rate of heat exchange between water and air. Splash fill is a multilayered structure which forms small droplets to increase contact between air and water, also resulting in a high heat transfer rate. Selection of the fill media shall be based on water quality: film fill is ideal for clean water, while splash fill is suitable for poor-quality or dirty water with high solids content.

Special solutions are available for reducing the risk of bacterial growth, e.g., anti-legionella fill media which works by disrupting the metabolic process of microorganisms and interrupting bacterias' ability to grow and reproduce.

Drift eliminators are a vital component of maintaining the efficiency of a cooling tower and minimizing the loss of water. The structure of a drift eliminator provides multiple deflections of the air stream, thus forcing water droplets which are carried away with the airflow to deposit on the surface of eliminator and drip down to the collection basin.

Pros and Cons

Wet (open-circuit) cooling towers more suitable for large industrial facilities that require cooling of vast volumes of water:

Pros:

Ability to cool down process water below dry bulb temperature;

Reliable operation in hot ambient conditions;

High cooling capacity per unit.

Cons:

High equipment and installation costs;

High operating costs which include frequent water treatment/refill, maintenance of system components, electricity costs;

Relatively high water consumption due to evaporation;

Formation of rust along the pipework;

Growth of bacteria, including legionella.

Dry coolers are particularly suited for small-to-medium industrial and commercial applications and free cooling systems:

Pros:

Low initial, operating, maintenance costs;

Ability to work in any climate conditions, from hot and humid to extreme cold;

Wide variety of unit designs that provides the possibility to suit it for nearly all environments and applications;

Minimal system fouling and process water contamination.

No water loss.

Cons:

Cannot cool the process water below dry bulb temperature (without adiabatic pre-cooling);

Relatively low capacity per unit.

As closed-circuit systems, dry coolers deliver several benefits compared to wet cooling towers, including lower initial costs and maintenance, improved system reliability, and increased uptime. Being equipped with evaporative pre-cooling, dry coolers offer the efficiency which is, as for wet-type cooling towers, only limited by wet bulb temperature.

In light of the above, the most significant factor in the choice between open-circuit cooling tower and dry cooler remains the system capacity. Continuous introduction of new efficient technologies such as microchannel heat exchangers, EC fans, intelligent controls, and others let consider dry coolers as an effective part of new environmental friendly thermal systems.

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Dry coolers vs. wet cooling towers | Insights | Kaltra

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Dry coolers vs. wet cooling towers: pros, cons, and differences in working principles, system design, and areas of application.

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Case Study: (Consulting Specifying Engineering 2022)

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Case Study: (Consulting Specifying Engineering 2022)

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https://www.csemag.com/articles/case-study-specifying-a-water-cooled-chiller-plant/

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A confidential project built in the southern United States demonstrates an ideal use of the water-cooled chiller plant. The project envisioned is a single-story system operations system to house the owner's transmission control operations for the foreseeable future. The new facility is located on a wooded greenfield site.

A guiding principle for the design of the facility was to eliminate all single points of failure of critical systems. The building is storm-hardened to protect against hurricanes, tornadoes, flooding and other natural events.

The scope of certification work included design and construction of the single-free standing building and associated landscaping, drive aisles and surface parking. A portion of the site is designated for possible future expansion space, but the majority if the wooded site was preserved and enhanced, through the introduction of native grass seed at the understory of the tree canopy in the wooded area. Existing site wetlands and a pond also were preserved.

Conditioning of the noncritical, nonshielded portion of the building was done with multiple variable refrigerant flow systems. Each VRF system consists of a condensing unit (or headered-stack of condensing units), multiple refrigerant distribution devices (orientation varies with manufacturer) and multiple VRF evaporators. Each evaporator controls a zone thermostat. Pretreated outside air is ducted to each individual evaporator.

Conditioning of a loading dock area of the building is being done with a packaged direct expansion roof-top unit, unit heaters and a high-volume low-speed ceiling fan.

Outside air (ventilation) conditioning is done by a packaged DX unit. This unit consists of multiple stages of filtering, variable speed drive-driven supply and return fan arrays, an energy recovery wheel, silicon controlled rectifier electric resistance heat, ultraviolet lights, humidifier and motorized isolation dampers. The ventilation air is ducted to individual zones throughout the building using duct pressure transmitters.

The central plant is a water-cooled chilled water system that serves all cooling equipment inside the shielded portion of the building. The system consists of redundant cooling towers, which provide condenser water to a basin. The condenser water is then pumped through a submersible pump from the basin, through a condenser water loop to a heat exchanger (condenser water supply/chilled water return), to the condenser section of each chiller. The chilled water is in a primary-secondary loop, which goes from the chiller, through the building, back through the heat exchanger and into the return side of the chiller.

Chilled water serves multiple air handling units, including underfloor air handling units, computer room air handlers and suspended fan coil units. The underfloor areas are served with thermostatic zone terminals and air supplied desks with individual thermal comfort adjusters. All heating is electric resistance. Direct digital controls are synced with a building automation system.

Do you have experience and expertise with the topics mentioned in this content? You should consider contributing to our CFE Media editorial team and getting the recognition you and your company deserve. Click here to start this process.

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Case study: Specifying a water-cooled chiller plant | Consulting - Specifying Engineer

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A confidential project built in the southern United States demonstrates an ideal use of the water-cooled chiller plant. The project envisioned is a | Consulting - Specifying Engineer

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High Cost

High Maintenance

Complicated Installation

Requires mechanical room for Installation

Less Efficient in Humidity

https://jcyounger.com/advantages-disadvantages-watercooled-chillers/

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Chillers play an important role in many industries. They help keep medical machines running consistently, and they keep milk cool until it goes to markets. They assist in the pharmaceutical industry, the brewery industry, and in meat and poultry processing. If you're looking for a chiller for your business, one of the things you'll have to decide is whether you need an air-cooled chiller or a water-cooled chiller. To assist in your research, here are the main advantages and disadvantages of water-cooled chillers.

Advantages
Longer Lifespan
Water-cooled chillers usually don't need replacement as often as air-cooled chillers do. They aren't exposed to outdoor elements such as rain, snow, ice, and heat, which makes them less vulnerable.
Quiet Operation
While air-cooled chillers have ducts and vents that create noise, water-cooled chillers operate quietly. The flow of water through the system doesn't result in the same noisy expansion and contraction that's heard in air-cooled chillers. Quiet operation is particularly important in environments such as hospitals and schools, where noise can cause disturbance to occupants.
Energy Efficiency
The film coefficient is 10 to 100 times better in water-cooled chillers versus air-cooled chillers. This means that water-cooled chillers transfer heat more efficiently. The result to businesses is a savings on energy costs.
No Open Space Needed
Air-cooled chillers need to stay outdoors in an open space with plenty of fresh air to operate. Water-cooled chillers stay inside buildings, which makes them ideal for companies that don't have access to enough outdoor space.
Safety
Water-cooled chillers use water as a refrigerant instead of toxic chemicals. This makes them safer for people who have contact with them.

Disadvantages
Higher Cost
Air-cooled chillers are cheaper than water-cooled chillers because they don't require parts like cooling towers and condenser water pumps. Many companies feel that the longer lifespan and savings on energy costs make water-cooled chillers worth the initial high investment, however.
More Maintenance
Since water-cooled chillers have more parts, they require more maintenance. Companies should prepare to pay for periodic inspections, water treatments to remove impurities, and regular cleaning of the chiller's machinery. More maintenance also means more downtime for the chiller. The more parts a machine has, the more things there are that can go wrong with the machine, which means water-cooled chillers are more likely to require repairs than air-cooled chillers.
Complicated Installation
The extra parts in water-cooled chillers also make installation more of a hassle. This can mean higher labor costs for installation of water-cooled chillers as opposed to air-cooled chillers.
Requires Mechanical Room
Businesses need to have a mechanical room to house a water-cooled chiller. This is to ensure that the chiller will function properly with its cooling tower and extra components.
Not Ideal For Drought-Stricken Areas
Since they use a good amount of water, water-cooled chillers aren't great in regions that have water shortages. Companies that pay water costs can expect these bills to rise with the use of a water-cooled chiller. Some drought-stricken areas also have restrictions on water-cooled chiller use.
Less Efficient in Humidity
Although water-cooled chillers are overall more efficient than air-cooled chillers, they'll operate less efficiently in humid environments. This is because humidity raises the wet-bulb temperature, which indicates how efficiently water absorbs heat. Water-cooled chillers in humid environments may also make building occupants feel cold and clammy.

J.C. Younger Company rents out air and water-cooled chillers to professionals throughout many industries. We've been a family owned company in the chiller business since 1956, and our products are USA-made. We're pleased to offer the most unit protection in the industry, and we're available to speak with you 24/7. To talk more about whether an air-cooled chiller or water-cooled chiller is right for you, please contact us.

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Advantages And Disadvantages of Water-Cooled Chillers

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Chillers play an important role in many industries. They help keep medical machines running consistently, and they keep milk cool until it goes to markets. Th

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UCD University Club

https://entropic.ie/case-study/ucd-university-club

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Cooling Performance

Air flow Problems

Sound Issues

Space requirements

https://usacoil.com/common-problems-with-fan-coil-units/#:~:text=Air%20Flow%20Problems,resistance%20found%20on%20many%20installations.

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https://www.envirotec.co.uk/case-studies/napp-pharmaceuticals/

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The Challenge:
Napp Pharmaceuticals approached us because of our experience of their industry's strict specifications and regulations. The Challenge? To overhaul and refit twenty-four air handling units originally supplied by another manufacturer outside of office hours and over the Christmas closure period.

Fresh thinking:
We brought 45 years of experience of refurbishing AHUs, including those supplied by our competitors, to bear. Our engineers orchestrated a multi-faceted programme to deal with restricted space, limited access and out of hours working. Typically, refits began at 6pm on Friday evening and were completed before the start of business the following Monday. We designed and manufactured split replacement coils and fan scrolls to pass through the available doorways and ensure that the affected areas suffered no disruption.

Each weekend a unit was completely overhauled with:

New dampers.

New heating coils with supplementary 'stab-in-type' electric heaters.

New cooling coils with eliminators.

New stainless steel drain pans.

New galvanised AHU floor.

New filters and supporting frames.

New fan scrolls, motors, drives, A/V's & flexes.

New 'special' inward and outward opening access doors.

Replacing complete sections of casing where the units had deteriorated beyond repair.

Benefit to client:
A better environment with reduced running costs. No plant replacement costs or the need for the heavy plant that would entail and, best of all, no disruption or loss of production. Each Monday morning, as the programme progressed, workers would return to improved air and working conditions.

Testimonial:
"Envirotec have helped us with AHU overhaul in some very demanding inaccessible areas. They have completed this while still maintaining a very high degree of quality and with the utmost professionalism." - Paul Buckley, Napp Pharmaceuticals

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Air Handling Unit (AHU) Overhaul Case Study: Napp Pharmaceuticals

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Napp Pharmaceuticals approached us for our experience of their industry's strict regulations to overhaul and refit twenty-four AHUs. Click to read more.

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Vulnerable to Filter Loading

Inefficient Configuration for Low ISO Cleanrooms

Higher Airflow Requires More Power

https://angstromtechnology.com/fan-filter-units-and-air-handling-units-whats-the-difference/#:~:text=Disadvantages%20of%20Relying%20on%20an,forced%20through%20a%20limited%20space.

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If you're considering different options for filtering and treating the air in your cleanroom, you've likely come across fan filter units (FFUs) and air handling units (AHUs). What's the difference, and how can you design a cleanroom filtration system that will offer you the control you need with maximum efficiency? Let's break down fan filter units and air handling units in more detail.

Fan Filter Units and Air Handling Units: What's the Difference?

Both FFUs and AHUs filter and treat the air in cleanrooms and controlled environments. However, they do this differently. The most significant difference between these systems is their connection to cleanroom HVAC.

Air Handling Units

An air handling unit is synonymous with the HVAC system and acts as a centralized unit for air processing and filtration. When an air handling unit is solely responsible for delivering clean air to the cleanroom, a fan pushes treated air through a filter positioned right before the plenum and into the room.

AHUs can be simple or complex, depending on the needs of the cleanroom. Simple AHUs consist of a HEPA filter, a heating coil, a cooling coil, and a fan to push air through the unit. More complex AHUs can also contain a sound attenuator, return fan, relief air section, humidifier, intakes for outside air, and a discharge plenum.

Fan Filter Units

Fan filter units sit in the cleanroom envelope, and to reach air cleanliness standards, you can increase or decrease the quantity as needed. They are individual units that each deliver filtered air into the cleanroom. The HVAC unit still controls temperature and relative humidity, but air enters the cleanroom after terminal filtration through the separate FFUs.

Fan filter units have a more straightforward construction multiplied across the cleanroom to reach peak effectiveness. They consist of a HEPA filter, a pre-filter, and a fan to push air through the unit. The more stringent the cleanroom classification, the more fan filter units are required to reach particle count requirements. For example, while an ISO Class 8 cleanroom may only need 5-15% of ceiling coverage dedicated to FFUs, ISO Class 3 cleanrooms may require 100% ceiling coverage with these powerful filtration units.

Fan Filter Units and Air Handling Units: Pros and Cons

While one system is not inherently better than the other, fan filter units offer some advantages over an air handling unit alone.

Drawbacks of Relying on an Air Handling Unit

AHUs deliver fresh, filtered air directly into the cleanroom. Because the entire system is in-house, all filters, heating, and cooling coils are maintained in one central location. It may seem like a more straightforward construction, but using AHUs to manage the treatment and filtration of air for an entire cleanroom requires more energy and becomes more inefficient (and expensive) as your ISO class gets lower.

Disadvantages of Relying on an AHU for Filtration

Higher Airflow Requires More Power: The entire system pushes air into the cleanroom through one or a few filtered openings. Depending on your cleanroom size and classification, a lot of air is forced through a limited space. Using an AHU to cool and filter the air in a cleanroom takes a lot of power, especially at lower ISO levels.

Inefficient Configuration for Low ISO Cleanrooms: As the ISO class gets lower, there's more reliance on the AHU and filter to provide clean, cool air for the room. When cleanrooms get more complex and house large or sensitive equipment that generates a lot of heat, making it challenging to manage heat and ACH with just an AHU.

Vulnerable to Filter Loading: AHUs should run 24/7 to prevent filter loading. This is when particles settle on filter media and are forced through when the system is turned back on. Tears and filter loading can reduce filter performance and are challenging to spot and address.

Why Implement Fan Filter Units in Your Cleanroom

Modular and Customizable: Each filter and housing is an independent system mounted in a modular ceiling grid. FFUs are entirely customizable in size, flow rate, and filter options. When designing a cleanroom filtration system with FFUs, you have more flexibility to meet your classification, project, and budget requirements.

Thorough and Efficient Cleanroom Filtration: Fan filter units are 99.99% efficient with HEPA filters. Or 99.9995% with ULPA, making them ideal for various sensitive applications. They also produce less noise than a large AHU.

Easy to Modify: Fan filter units are ideal for projects that need room to grow. To meet increased cleanliness requirements, you can simply add more FFUs. With AHUs, this would require a certified contractor to reconfigure the system and run extra conduit.

Easy to Maintain: FFUs also present an advantage during maintenance. Self-contained units can be accessed and replaced as needed without having to disable the entire system.

Many cleanrooms opt for modular construction with fan filter units installed in a grid ceiling. Especially those that must support sensitive processes at a lower ISO level. That's not to say that an air handling system couldn't do the job just as well. But the easy installation and maintenance of FFUs make them a more widespread, efficient, and cost-effective choice.

Advantages of Using Fan Filter Units

To meet productivity demands, a reliable and easily accessible filtration system is a must. And the higher filtering power means that sensitive applications, such as those working with sensors or delicate electronics, are protected from the smallest particles with accuracy and consistency.

CLEANROOM DESIGN & BUILD PROJECTS WITH ANGSTROM TECHNOLOGY

As Angstrom Technology are cleanroom specialists. We've developed proven envelope solutions and reliable cleanroom HVAC designs for many applications. The Angstrom Technology group pride ourselves on our in-house expertise and capability to deliver over 100 cleanrooms annually across America, the UK, and Europe.

If you're interested in designing a cleanroom that runs at peak efficiency to cut unnecessary costs, get in touch with the cleanroom experts at Angstrom Technology. We're happy to help design the right airflow pattern and install the solutions that will make your cleanroom cleaner.

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Fan Filter Units and Air Handling Units. What's the Difference? - Angstrom Technology

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There is a difference between fan filter and air handling units. While one system is not better than the other, fan filter units do offer some advantages.

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https://www.iesve.com/discoveries/view/32039/vav-systems-in-apachehvac

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VAV Systems in ApacheHVAC

A Variable Air Volume (VAV) system is one of the most common HVAC systems used in buildings. The basic concept is that the volume of the air entering the thermal zone changes as the demand for heating or cooling changes, using a variable speed/frequency drive on the supply air fan, while maintaining minimum ventilation requirements. Some of advantages of a VAV system include:

a) Better temperature control
b) Better humidity control
c) Lower system fan energy
d) Less fan noise

Fundamentals of a VAV System

Since the volume of air entering the space is controlled by a fan, we can see that two of the advantages of having a VAV system are directly related to the fan. This has been further explained in the figure below, where we compare the VAV system with a Constant Air Volume system (CAV).
Figure 1: VAV vs CAV systems
From the figure above, we can see:

a) In the "Volume Flow vs Power" section, the CAV is providing air at its design flow rate capacity, whereas in a VAV system the airflow fluctuates between the design flow rate and the VAV minimum flow rate (VAV turndown). As a result, the VAV fan uses less energy than a CAV fan. This is due to the fan laws, or affinity laws, which explains the cubic relationship between fan power and flow rate.

b) Another example of the fan laws is in the "Fan performance curve" section where the fan power is varying with the flow rate for VAV system. The flow rate of the fan varies using a Variable speed/frequency drive (VFD/VSD). In a VSD/VFD system, the speed of the fan modulates to control the airflow into the zone(s).

A frequently asked question about a VAV system is, " What is an acceptable VAV turndown?" Typical VAV turndowns may be between 20% (California's Title 24) and 30% (recommended by ASHRAE). However, some studies suggest that a VAV system can have a turndown of as low as 10%. The VAV system shown in Figure 1 has a turndown of 20%.

Multizone VAV System Operation in IESVE Software

Multizone operation been explained in detail in the "ApacheHVAC Controllers: Example of VAV controllers" whitepaper. This white paper explains how a Typical VAV operation (Figure 2) is setup in ApacheHVAC.

Figure 2: Typical VAV Operation cooling setpoint of 75 °F (23.89 °C) and heating setpoint of 69 °F (26.56 °C)

In addition, this on-demand learning video HERE explains how the VAV control strategy is implemented in ApacheHVAC.

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High Costs

Controls Complexity

Ceiling Space Consumption

https://schnackel.com/blogs/pros-and-cons-of-vav-systems

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Commercial building owners understand the importance of comfortable and energy-efficient spaces. This blog post will explore the pros and cons of VAV systems.

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https://www.esmagazine.com/articles/98196-two-pipe-fan-coil-unit-controls

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Cannot Heat and Cool Simultaneously

Coil Requires changeover sensor

is dependent of the mode of the building

https://www.neptronic.com/TechTime/20150716/WhatsTheDifference.aspx#:~:text=2%20Pipe%20Fan%20Coil&text=This%20type%20of%20fan%20coil,actual%20mode%20of%20the%20building.

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https://files.bregroup.com/bre-co-uk-file-library-copy/filelibrary/pdf/projects/aircon-energy-use/F_AirConditioningEnergyUseAnnexFFinal.pdf

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https://entropic.ie/find-the-perfect-fan-coil-unit-for-your-project/

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Fan Coil Units Case Studies - HVAC Solutions - Entropic Limited

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Air Sterilisation Units for Hygienic Healthy Air

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Complex System

Design complications due to number of pipes

Initial and installment costs

Space Requirements

https://www.yesncer.com/article/difference-between-2-pipe-fan-coil-unit-and-4-pipe-fan-coil-unit-i00117i1.html#:~:text=Disadvantages%20of%20the%20f4%20pipe,of%20this%20system%20is%20limited.

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Four-pipe fan coil unit air conditioner refers to a fan-coil air conditioner with both cold and hot coils. Each group of coils is fed once, totaling four coils, so it is called four tubes. The two groups of water pipes are connected with cold water and hot water respectively, that is, cooling and heating can be switched at any time in the four seasons of the year, so that some rooms can supply heat while others can supply cold. Therefore, it has high standards and costs.

There is only one set of coils in the2 pipe fan coil unit air-conditioning box, once in and once out, cold water in summer and hot water in winter. Such a system allows the entire area to supply only cold or heat at the same time. Compared with four-tube fan coil, it saves a water system, so its standard is relatively low and its cost is low.

Advantages of the 4 pipe fan coil unit system: ① The terminal equipment of each fan coil unit can freely choose the operation mode of heating or cooling at any time without mutual interference, and the served air conditioning area can independently control the temperature and other parameters; ② save energy, all energy consumption in the system can be provided according to the requirements of the terminal, unlike the three-pipe system, there is no problem of cold and heat offset.

Disadvantages of the f4 pipe fan coil unit system: ① large investment and relatively complicated operation and management; ② due to more pipelines, the system design becomes more complicated and the pipeline takes up more space. Due to these shortcomings, the use of this system is limited.

During the year-round operation, the fan coil unit air conditioning system with 4 pipe water fan coil unit system should be adopted for the fan-coil air conditioning system with frequent alternate switching of cooling and heating conditions or simultaneous use. Therefore, it is more suitable for buildings with large inner areas or buildings with high standards of air conditioning and investment permission.
For fan coil unit air conditioning systems operating all year round, when only seasonal cooling and heating conversion is required, a 2 pipe water fan coil unit system should be adopted. The practice of large-scale construction of high-rise buildings, especially high-rise hotel buildings, shows that the 2 pipe fan coil unit system can meet the air conditioning requirements of most hotels, and is also a widely used fan coil unit air conditioning water system for multi-storey or high-rise civil buildings.

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Difference between 2 pipe Fan Coil Unit and 4 pipe Fan Coil Unit

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When to use 4 pipe fan coil units and what are the advantages of 4 pipe and 2 pipe systems, let's find out today.

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According to Forbes 2023 the average cost of a HVAC System is 8,000 dollars US

https://www.forbes.com/home-improvement/hvac/new-hvac-system-cost/

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The Link provided shows a multitude of different Prices Regarding the different Aspects involved in HVAC system installations

https://www.forbes.com/home-improvement/hvac/new-hvac-system-cost/

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What Is an HVAC System?

As the acronym implies, an HVAC system covers all of the heating, ventilation and air conditioning components in your home. If you're considering updating your HVAC-or if a broken system in the dead of winter leaves you with no choice-you have some decisions to make.

You can heat your home with a furnace or boiler and cool it with an air conditioner. Or, depending on if the local climate allows, you can pull off both tasks with a heat pump. These technologies even combine for great efficiency.

HVAC System Costs by Type

There are many types of HVAC systems. A split system, for example, separates the cooling elements between the inside and outside of your home. Mini-split systems allow for zoned temperature control without ducts and hybrids combine system styles. Let's take a look at popular options.

You can choose to install a furnace and a separate AC split system. The prices above combine the cost of a new furnace plus the cost of AC installation. Furnaces generate heat either by combusting fuel sources, such as natural gas or oil or by using electricity.

Split AC systems consist of two primary components: an outdoor unit and an indoor unit. The outdoor unit comprises a condenser and compressor, while the indoor unit typically holds the air handler and evaporator coils. The indoor unit draws hot indoor air inside of it, moving it through an evaporator coil where the refrigerant absorbs the heat and cools the air, sending it back into your home through ducts. Ductwork usually adds between $10 and $20 per linear foot for materials and labor.

While a furnace uses forced hot air to heat your home, a boiler sends heated water or steam through radiators, baseboards or pipes. The size of your boiler, and thus the price, will come down to how many BTUs (British Thermal Units) you need to heat your home. Colder climates in larger homes require more BTUs and vice versa.

Similar to furnaces, boilers are either powered by electricity, gas, oil or propane. The HVAC professional will often pair your central AC system with proper ductwork based on your home size and layout.

Older homes and those without the room for ductwork can benefit from a customizable mini-split system. In this setup, a traditional furnace heats your home with an indoor unit, often in the basement. The AC, however, splits between a compressor outside the house and a series of indoor units, known as heads, in individual rooms. Spending a bit more on the cost of a mini-split air conditioner allows homeowners to cool off individual zones.

Quickly growing in popularity for its efficiency, a heat pump transfers warm and cool air in and out of your home to balance your indoor temperature.

An outdoor heat pump unit contains a condenser, a compressor and an evaporator with a refrigerant coil. As the air passes over the coil, it moves in or out of an indoor unit. Indoors, an air blower circulates the cooled or heated air throughout the home, typically through a ductwork system.

The Department of Energy notes that an average home will use 50% less energy each year on electricity by using a heat pump.

Cold-climate dwellers can enjoy the perks of a heat pump by installing a dual-fuel hybrid system. A heat pump circulates air in warm and cool times of the year, but the furnace will pop on when the temperatures dip. While some cold-climate heat pumps handle lower temperatures, adding a furnace will offer peace of mind during extreme winters.

Combine the energy efficiency of the heat pump and the customizable ductless design, and you'll get a mini-split heat pump. While the outdoor heat pump unit stays the same, the indoor unit includes multiple air handlers in individual zones of your house. Additional zones will raise the installation and materials price.

Geothermal heat pump costs are a bit of an outlier due to the extensive installation. The heat pump design sources its hot and cool temperatures from the surrounding water and soil. A team of professionals must excavate the property to install underground pipes to serve the system. While costly and highly dependent on your landscape, the Department of Energy mentions energy savings between 30 and 60% when using this system.

HVAC Installation Cost by Size

When you initially estimate the cost of a new HVAC system, the size of your home can help you determine the proper size, and thus the cost, of your system. But it's only an estimate since several other factors are at play, including:

Efficiency ratings

Regional climate

Humidity

Insulation

Window size

Age of your home

As a very general rule of thumb, you'll need an HVAC system between 20 and 60 BTUs per square foot, or an average of 40 BTUs per square foot, to heat and cool your home. So if your home is 2,000 square feet, you'll likely need a system with around 80,000 BTUs, which might cost around $6,000 to $12,000, including installation. However, these costs can be considerably lower or higher depending on the aforementioned cost factors, so speaking with a pro to get a unique estimate is always recommended.

HVAC Installation Cost of Parts

The versatility of an HVAC system means that you can build a rather unique HVAC system for your space. Breaking down the cost of the parts of an HVAC, therefore, may give you the clearest picture of the final price.

Air Conditioner

You can choose from window units, wall-mounted AC models or a central AC condenser and compressor. If you choose central air, an outdoor unit will connect to either ductwork or individual mini-split heads.

Here are some of the common costs of AC installation, including labor:

Furnace or Boiler

Boilers and furnaces vary in price based on their Annual Fuel Utilization Efficiency (AFUE) rating, size, connected radiators or ductwork and the cost of labor in your area. Here are some average furnace installation costs and boiler prices to keep in mind.

Heat Pump

Heat pump technology keeps homes in temperate regions in balanced comfort. And while heat pumps' comparatively high installation costs mean spending significant money up front, they can often save you money on ongoing operational costs compared to other systems.

And remember, heat pumps come in a range of installation options:

Ductwork

Both the cost of ductwork materials and labor will add to your HVAC installation price tag. As a rule of thumb, assume that ductwork will cost between $10 and $20 per linear foot, and you'll likely need an average of 50 and 200 feet.

Thermostat

Today, you have your pick of top smart thermostats that adjust your home's temperature by the time of day, temperature or humidity. You can also choose a unit that's compatible with your smartphone. While some HVAC pros will include the cost of a thermostat in the overall price, they often cost between $125 and $250.

Humidifier or Dehumidifier

Humidifiers add moisture to your home's indoor air, increasing the humidity, which is beneficial in dry climates or during the winter when heating systems dry out the air. Dehumidifiers remove moisture from the air, decreasing humidity, which can make homes more comfortable in humid regions and seasons.

Humidifiers typically range from $400 to $1,200, but most homeowners pay around $600. However, some designs, such as steam humidifiers, can push the cost over $2,000. Dehumidifiers are more expensive since they have more complex components, with the price of a whole-house dehumidifier usually ranging from $1,300 to $3,500.

Factors That Affect the Cost of HVAC System Installation

Curious about the wide cost ranges in many of our HVAC system examples? Here are the factors that can sway the costs.

Labor

Between $500 and $2,500 of the total cost of a new HVAC system goes to labor. The price will vary depending on your local cost of living, demand for HVAC installers and the price of specialists for digging trenches or working on a historic home.

Type of System

While we covered just several of the most common HVAC systems, it goes without saying that each installation is unique. The type of system you choose will shift the price in either direction. Ductwork, for example, adds to the final cost both due to material and additional labor.

HVAC Efficiency Ratings

Air conditioners and heat pumps measure efficiency in SEER, or seasonal energy efficiency ratings. Heating units, such as heaters and boilers, use the AFUE rating system. In both cases, the number measures how much of the fuel converts directly to energy.

You will pay higher rates for heating and cooling units with higher SEER and AFUE numbers, but you may find federal tax incentives for purchasing energy-efficient models.

Extent of Replacement

The extent of the replacement is another important cost factor. In some cases, you don't need a full replacement; instead, you might only need to replace or repair certain components, which can save you money on a full replacement. For instance, furnace repairs cost around $300, on average, while an AC tune-up runs around $120 per unit or between $350 and $750 for large central air systems.

But if you're doing a full replacement, your home's age, existing ductwork and insulation can all affect your costs. For example, older ductwork might not be compatible with modern HVAC systems, so you might need to replace your ductwork, driving up costs. Plus, if your home has poor insulation, you might need a system with a greater capacity to heat or cool it. Or you might need to pay to install new insulation.

Location of Your Home

Your local climate dictates the size, type and placement of your heating and cooling design. Where you live can alter the price of your HVAC installation due to:

Humidity levels

Seasonal temperatures

Home size in your area

Home age in your area

State and local rebates for energy efficiency

Location of the System

Many AC units have one component inside and one outside of the home. Most outdoor components sit on the side or back of a home, but some condos, townhomes and shared homes require the unit to be mounted on the roof. Roof mounting will likely add another $1,000 or so to your final costs.

Additionally, if it's difficult for your pro to access certain areas of your home or if you want to install a decorative fence to conceal the unit, your costs can increase by $100 or $200.

Adding Zones

When they pertain to HVAC systems, zones indicate the designated areas in your home that your system will heat and cool. If you have a very large home or a home with multiple stories, you might need to install more than one HVAC system to accommodate additional zones, which can significantly increase your costs.

Permits

Some HVAC installations require you to obtain a local permit. Permit costs vary quite a bit depending on your municipality, but you can expect to pay between $250 and $400 for an HVAC system permit. If you need to update your plumbing, you might need a permit for that as well, which can range anywhere from $50 to $500.

Additional Costs Related to Installing a New HVAC System

Several other costs can come with installing a new HVAC system, including the cost to remove and dispose of an old system.

Insulation

Insulation helps regulate your indoor air temperature, which means your HVAC system doesn't have to work as hard to keep your home comfortable. In some cases, you need to add insulation when installing a new system. You might also want to update existing insulation to supplement your new system. Either way, you can expect to pay around $1,500 for new insulation.

Removal and Disposal Costs

If you have an old HVAC system, your pro might include removal and disposal costs in your overall installation estimate for a new system, but they might also charge an additional $60 to $500 to remove and dispose of it.

Asbestos Removal

Older homes might have asbestos in the floors, walls or ceilings, which is harmful to your health. If your HVAC pro finds any asbestos when installing the system, you should hire a professional to safely remove it. Asbestos removal usually costs between $5 and $20 per square foot.

When to Install a New HVAC System

It is best to start the HVAC installation process in the spring when the weather is generally temperate. At this time of year, a few days without heat or AC shouldn't interrupt your daily life. You might also consider replacing your HVAC in the early fall for similar reasons.

Since these are popular times to have an HVAC system installed, try to book with a local team as early as possible to avoid last-minute rates or delays.

You may need to replace your HVAC systems soon if::

It's more than 15 to 20 years old

You're frequently paying for repairs

Your energy bills have increased

Temperatures are inconsistent from room to room

The system has become very noisy

Your system frequently turns on and off

The system struggles to keep up with the weather

How to Save Money on a New HVAC System Installation

A new HVAC installation is a significant investment but one that can save you from the cost of frozen pipes, mold issues from high humidity and a whole lot of discomfort. Still, you can cut costs either during installation or in the long run with a few tricks.

Research rebates and tax credits for high-efficiency HVAC systems

Consult your homeowner's insurance plan if the previous system broke down due to a covered incident.

Speak with at least three HVAC installation teams to compare design and cost options.

Consider a heat pump if you live in a temperate climate.

Opt for a ductless mini-split system to lower ductwork installation costs.

Invest in a smart thermometer to lower long-term utility costs.

To arrive at the average costs in this article, editorial team members surveyed a range of providers and cost databases on national and local levels. All averaged figures were correct at the time of publication and may be subject to change.

Frequently Asked Questions (FAQs)

How often should an HVAC system be replaced?

What is the longest-lasting HVAC system?

Is replacing your HVAC worth it?

How long does it take to replace an existing HVAC system?

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How Much Does A New HVAC System Cost In 2023?

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