Friday, June 4, 2010

What HVAC system should I use?

In most homes the HVAC energy use makes up the largest percentage of the home’s energy consumption. This information is becoming common knowledge as more individuals become energy savvy but many individuals still wonder which system is the best for them. There are various systems that can be used to heat the home but as certain system types are being phased out due to technology, such as boilers, other are beginning to rise to the top. These systems are heat pumps and furnaces. In most cases people are familiar with these systems but they may not realize which is better for them or what the differences in them are.

The first bit of information that a homeowner should understand about a system is that no matter what system is installed it should be installed properly. This is especially critical for the air conditioner. All systems must be sized and designed properly to provide quality and efficient heating and air. To start a load calculation must be performed. This is referred to as a Manual J calculation. Beyond sizing the system the ducts and registers must be sized to the system to properly provide conditioned air to the home. This is a lengthy process and for more information regarding proper installation please refer to my previous blog Why HVAC isn't just a lot of hot air .

Your system selection will depend on your climate location but here is some information about each popular system type.

1. Air Source Heat Pump: Air source heat pumps have the benefit of providing both heating and cooling function and are essentially an air conditioner that can work in reverse. Heat pumps do not create heat but rather transfer it from place to place. For this reason they are extremely efficient and can actually transfer more energy than what they consume. Air source heat pumps draw their energy from the outdoor air. Because of this they are not appropriate for areas of extreme cold. Also heat pumps can require a back up heat source for colder days. This is typically done with an electric backup. This electric back up can be extremely costly and therefore should be avoided as a heat source much as possible.

2. Hybrid Systems: A hybrid system is an air source heat pump with a gas backup. This is a good system for areas in which a heat pump is a good choice for the majority of the time but there may be short periods of extreme cold in which the backup heat strips on conventional heat pumps my run for extended period of times. Hybrids are most efficient in transition areas between warm climates and cold climates.

3. Ground Source Heat Pump: Ground source heat pumps work exactly the same as air source heat pumps but they draw their energy source from the ground. Since the ground stays at a constant temperature the heat pump is able to be more efficient. Ground source heat pumps are more expensive than air source heat pumps and extremely efficient air source pumps can come close to the same efficiency as low efficiency ground source systems. One bonus to ground source systems is many of them have the ability to heat water as well.

4. Furnaces: Furnaces are generally efficient than heat pumps but they are better in cold climates. This is due to heat pump efficiencies decreasing as the outdoor temperature decreases. Heat pumps require the use of electric heatstrips to make up for this deficiency.  Due to this furnances are a better fit in the colder climates.  In considering a furnace one must consider the climate they are in and if it is a better fit than a heat pump for their home.

5. Mini Splits: Mini splits are the same as air source heat pumps but they do not require the installation of ducts. This has several benefits especially for retrofits. Small units are placed in each conditioned space and can be individually controlled. By eliminating ducts you also eliminate the losses associated with ducts.

6. Air conditioners: There are little options available for air conditioners. If you are not using one of the heat pumps you must also install an air conditioner. If you are in a climate in which you must install an air conditioner choose one that has the highest efficiency appropriate for your area. For areas in which cooling is only needed for a few days a year an extremely high efficiency system may not be appropriate where as in areas of extreme heat the highest efficiency system will have a relatively quick payback.

Don’t turn up your thermostat more than 2 degrees at a time.

While this really only applies to heat pumps it is good information to know. By turning up the temperature more than 2 degrees the heat strips on the system will cut on. This is extremely expensive heat and will quickly run up your electric bill. If you have a programmable thermostat make sure you have one with adaptive recovery. This will prevent your system from trying to raise the temperature too much as one time and cutting the heat strips on.


  1. Geothermal Heat Pumps use 25-50% less electricity than a regular heating or cooling system. This saves you both money and energy.

  2. Thanks for sharing your ideas and thoughts, i like your blog and bookmark this blog for further use thanks again…

    Gas Ducted Heating Repairs

  3. You’re right. The effectiveness of HVAC systems rests on a lot of factors, so choosing the right system for your home is a crucial task. Aside from the tips you mentioned, it’s also important to consider the maintenance routine for your prospective HVAC system. Choosing an HVAC system that cannot be serviced by anyone near you is strongly discouraged. And of course, choose a system that is simple, so repairs can be done easily.

    Mignon Her

  4. When it comes to installing HVAC systems, hiring a professional is invaluable. Sure, you might know what you need, but professional contractors know the BEST for your house. That will erase any confusions and doubts that you may have, speeding up the process. And of course, you can always count on them to maintain your HVAC properly.

    Georgia Fuller

  5. Mignon and Georgia had valid points. Actually, their tips can be synthesized to create a good HVAC installment plan. If you have no idea what system is the best for your house, I suggest taking multiple estimates. Remember that the parts and labor are parts of your expenses, and these again depend on the type of HVAC system you’re going to get.

    Kurt Verdejo

  6. In commercial HVAC systems which are more complex you should inspect at least 10% of the systems components. This means looking at the air handler (filters, coils, condensate pans/drain lines, dampers, gaskets etc.), any fan coils, supply ductwork and its internal components (registers, dampers, mixing boxes, reheat coils etc), return duct work and its components (grilles, dampers, plenums, etc). You are basically looking at a representative sample of anything in the air stream. Plus, other exhausts systems like bathroom, laundry, general.
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