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Home Fix: Solving a common air conditioner complaint

By C. Dwight Barnett | Tribune News Service Published: September 23, 2016 4:00 AM

Q: I'm having a problem with air conditioning. The home's bedrooms are warmer than the other rooms in the home, even at night when it's cooler outside.

One worker with the air conditioning company told me it was because the furnace is in the garage at the opposite end of the home, and another suggested I change the type of filter we use. One worker even went under the home to see if the ducts were okay. I paid them for cleaning and servicing the air conditioner, but it's still warm in the bedrooms. Is this due to the very hot weather or something else?

A: Of course the warmer the weather, the harder the air conditioner has to work to cool the home. I assume from your question that you have a home with a crawlspace where the worker went under the house.

Since most of the home cools satisfactorily, I further assume that the outside unit of the air conditioner is of a proper size for the area of the home being cooled. You also have an attached garage where the furnace is located.

There are a few things that can affect the cooling from one end of the home to the other. Make sure you have an even layer of insulation adequate for your location over the entire attic space of the home, especially the warmer bedrooms. Adding insulation can improve overall comfort to the living areas of the home.

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Have an experienced HVAC (heating, venting, air conditioning) technician inspect the ducts under the home and in the attic. The supply ductwork should have been designed by the original installer to ensure the air being pushed through the ducts by the fan reaches all of the rooms equally.

Proper sizing of all the ducts is very important to ensure the comfort of the home's occupants. All of the ducts, both supply and return air ducts, need to be sealed as airtight as possible. If needed, use only a metallic tape made for ductwork or a duct mastic to seal all joints and seams of the ducts. If the ductwork in the crawlspace is condensing, where drops of water form on the outside of the ducts, this is a sure sign you are losing some cooling to the crawlspace and the ducts need to be insulated. Ducts that are installed in a hot attic space need a thick layer of insulation on the top, bottom and on both sides of the ducts. A suggestion that the filter needed to be changed may help to increase airflow. Sometimes a dirty filter can reduce the airflow and other times it is the better filtration quality of the filter that reduces airflow.

While we always suggest filters that have better filtration ratings, some HVAC systems are designed such that a better quality filter can cause many issues with the operation of the system. Proper maintenance requires the filter or filters be changed often. Another source of air leakage may be the furnace, which is located outside of the home in the garage.

Seal as many of the seams and openings on the furnace and coil housings you can find. Use replaceable duct tape to seal the filter access. Keep the tape away from the flue if the furnace has one and from combustion air intakes for gas or propane furnaces. If, as I expect, the ducts are not properly sized or sealed, consider adding a mini-split or ductless air conditioner system for the bedroom areas.

Changing and/or sealing all of the ducts could be very expensive. Consider hiring a certified energy auditor to perform a blower door test of the home and duct system(s). The auditor can determine if the issue is from the house (bedrooms in particular), the HVAC system or both.

C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.

Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702 or e-mail him at d.Barnett@insightbb.com.


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