20 Things You Need To Know About Your HVAC System and Indoor Air Quality

20 Things You Need To Know About Your HVAC System and Indoor Air Quality
1. Expensive, pleated air filters have the potential to cause more problems than they solve. Unless your unit was specifically designed to use high efficiency filters (more than likely it wasn’t), you should use the cheapest filter available. Filters have one job and that is to keep your HVAC equipment clean. High efficiency filters cause increases in the static pressure of your system and typically they cause your fan to run harder to move the required air. As a result, you spend more money on filters, you have higher utility bills, you move less air, and air filtration is not any better. Make sure you change your HVAC system filters regularly.

2. Air filters have the primary function of keeping your HVAC machinery clean, specifically the coil. Typically, you have an indoor and an outdoor coil. It is important that you keep both clean. In many cases, the interior coil in your air handler is neglected. Service contracts are a good idea in order to have your coils cleaned periodically. If you do purchase a service contract, make sure the installer shows you the interior coil before and after the cleaning. Basically, your HVAC coils serve the same function as your car radiator.
3. Air conditioners should be sized to run continuously or almost continuously on the hottest days of the year. Your air conditioner is a dehumidifier and it removes moisture once the coils are cold. Units that you can hear “crank up” and run for short periods with big blasts of cold air are oversized. These oversized units actually use more energy than a properly sized unit that runs continuously. The oversized units do not dehumidify because of the short run times. The coils never get cold enough to remove much moisture. Much of the moisture on the coils evaporates back into the building making it feel cold and clammy. Spending money on extra tonnage instead of proper design and installation is a common occurrence that must be overcome.
4. Your fan should always be on automatic. It should never be in the “on” position. The “on” position causes more energy use. When the air conditioner stops, a fan in “on” position deposits the moisture accumulated on the coils back into the house. Finally, if the ducts are leaky which most are, the “ON” position causes negative pressures within the home that help to pull in contaminants such as mold, radon, insulation, dust, etc. from the outside.

5. Bedrooms should have return pathways for the air that is supplied. This can be accomplished by a return grille or jumper duct. Undercutting doors is never enough. Closing off bedrooms or grilles almost always causes pressure problems in other parts of the system or house and it should not be done.

6. Learn how to use your thermostat. Most of today’s programmable thermostats provide many money saving functions. But, not if you do not understand how to use it.
7. If you heat your home with an electric heat pump, do not turn it down in an effort to save money when you leave the home. When you return home, if you turn the unit up for more than 2 degrees, the strip heaters will “kick in” and they cost a lot of money to run. This is a big problem that is often seen in office buildings. The temperature is set back when the last person leaves at night and then the heat is “cranked up” in the morning causing higher energy costs than if the heat pump was allowed to run the entire time.
8. Freon should not be added to your system more than once every 5 years. If you add Freon more often than that, there is a good chance you have a leak. Be wary of the technician that comes to your home and just adds Freon. Have your technician explain to you how to read the gauges and what they are adding exactly.

9. Most homes I have inspected for moisture problems have had at least one exhaust fan disconnected or improperly installed. Make sure all of your exhaust fans are properly vented to the exterior of your home. Never vent bathroom, kitchen, or clothes dryer exhaust to the attic or crawlspace. It is a good idea to install timers on your bathroom fans to make sure that moisture is exhausted after you leave the room.

10. Your HVAC system should have a dedicated fresh air supply. When air is exhausted from your home, it must be replenished. Without a fresh air supply, air is pulled in through holes in your crawlspace and attic bringing with it radon, insulation, moisture, mold, pesticides, etc.
11. When purchasing a new unit, the SEER rating of the unit means nothing without proper design and installation of the unit and the duct work. Higher SEER rated units do not dehumidify as well as it is imperative that they are sized correctly.
12. Condensate lines must be properly installed and drained away from the foundation.
13. Duct work should be properly installed. Ductwork should be installed with dampers and the house should be balanced properly and the unit commissioned. Ducts should be tested for leakage the same as plumbing is tested.
14. If you have a woodburning fireplace and you can smell it when you turn on your heat, there is a good chance you have serious duct leakage and pressure problems. Carbon monoxide poisoning caused by backdrafting of fireplaces and appliances is a major safety issue that must be checked and corrected.

15. Always have a humidistat, smoke alarms, and Carbon Monoxide detectors installed in your home.
16. Ceiling fans only affect your comfort when you are under them. They do nothing the rest of the time except consume energy.

17. Return ducts should never be installed in closets regardless of whether or not the door has louvers. This restricts airflow and causes pressure problems.

18. Air handlers and ducts should be installed inside the conditioned space. What is the logic of installing an air handler and ducts in a 130 degree attic? A 30 degree attic?

19. Expensive and attractive wood grilles in hardwood floors severely restrict airflow.
20. Vent-free/house-vented fireplaces should never be operated. Candles, especially the ones in jars, should never be burned.

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