Top 8 Mistakes When Purchasing HVAC
Incorrect Sizing
Logic would tell you that having an under sized HVAC system would be a bad thing, but bigger is not always better in the HVAC world. The absolute best way to size a system would be to have an HVAC technician perform a task called a Manual J which will consider a multitude of variables that would affect a heating or cooling system. Unfortunately, a Manual J does cost money and trying to do one your self may cost even more. You can still get a close estimate for most residential homes with an online calculator. These calculators will take into consideration at least the square footage of the space as well as your location. Some of the more sophisticated calculators will add things like insulation type, desired temperatures, or how many floors there are. There is real science and math behind these calculators and you can find out more about that here.
Here are the problems with an undersized system; it will struggle to keep the temperature where you desire it to be, if it cannot achieve the desired temperature it will run constantly, and this will wear the system parts down quickly. This ultimately leads to a premature and costly replacement.
Under sizing can be a problem in both AC units and furnaces. An under sized AC unit will mostly just result in discomfort and the aforementioned premature system failure. An undersized furnace can lead to discomfort as well or to frozen pipes in extreme cases.
An oversized unit will turn on and off in short periods of time, known as short cycling. Short cycling can cause excess wear on parts of the system. Imagine flipping a light on and off constantly, consider how long it would last when compared to a light that is used normally. Another issue with oversized systems would be how they heat or cool an area. For this example, I will use a furnace. If a furnace turns on and heats up the area in 10 minutes most of the heat will be in the air (that passed through the furnace) which means all the objects that do not heat up as fast as air will still be cold and will cool the room down quickly when the furnace turns off. A properly sized system will heat (or cool) for a longer period of time allowing objects to change temperature as well. Getting the right size system is important for keeping your home comfortable.
Inadequate Efficiency
Another common mistake when purchasing HVAC systems is selecting a unit with efficiency below what is required for where you live. That’s right! The efficiency of the unit is not just about how much you will spend running it, but it is actually illegal to install a system if the efficiency does not meet requirements.
- Northern states can install a 13 SEER AC or higher while heat pumps are 14 SEER and 8.2 HSPF or higher.
- Southern states must have at least 14 SEER AC or higher as well as 8.2 HSPF for heat pumps.
- Southwestern states in addition will need 12.2 EER for systems under 45,000 Btu and 11.7 for systems over 45,000 Btu.
- Make sure you pick the right size system for your home
- Check the efficiency requirements of your area
- Check your furnace venting type
- If you are in a mobile home, verify the system is compatible
- Select the correct airflow configuration
- Verify that your system is a package unit or a split system
- Get it done professionally
- Don’t let contractors pull the wool over your eyes and buy direct
February 4, 2019
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