By Dwight Barnett
Scripps Howard News Service
Question: Our thermostat is in a family room with a southwest exposure and a fireplace. Consequently, the furnace isn't registering the actual temperature of the house. Our house is a two-story walkout that's 8 years old. The basement is very cold, the upstairs too hot and the main floor just right. Would it regulate the temperature in the whole house if we turned on the furnace fan and left it running at all times?
Answer: Running the fan on "on" instead of "auto" might help somewhat, but it would not regulate the temperature differences you need. The placement of a thermostat is critical to maintaining comfort levels. However, there is no way I can think of to properly control the conditioned air in a three-story home with just one thermostat. It is a fact of physics that warm air will rise and cold air will settle.
You might consider a zoned system. Zoning is an automatic baffle inside the ducts that opens or closes the ducts at the direction of a zoned thermostat. You can have as many zones of heating and cooling as you want. You have one master thermostat that directs the furnace to either heat or cool, but not both. Then each zone, say a second thermostat in the upstairs hall, would fire the furnace when heat is needed. The zoning baffles would close off all the ducts to the lower levels and open all the ducts to the upper levels.
If the upper levels got too warm, you would not be able to turn the upper-level thermostat to cooling and expect the air conditioner to come on. You would have only one "master" thermostat, usually on the main living area of the home. You would have to set the master thermostat to cooling before the air conditioner would be operational.
Can you do this yourself? No, the ductwork will have to be altered. While you're at it, have the old ducts cleaned and sealed at each joint and seam. Insulate ductwork in un-air conditioned spaces such as attics, crawl spaces and unfinished basements. This will save energy dollars, prevent sweating ducts and seal out air exfiltration and infiltration.
If a furnace is located in the basement of a two-story house, it will not efficiently cool the second story in a warm climate. Supplemental cooling would need to be installed if you do not have zoning.
A furnace which also has a cooling coil and is installed in an attic or over a finished area of the home needs to have a catch pan under the cooling coil to catch leaks during the cooling season. The catch pan must have a drainpipe that drains to a viewable location outside the home in order to alert the homeowners of potential problems.
A gas-fired or oil-fired furnace should not be located under a stairs, in a bedroom or a bathroom or in a closet accessed through a bedroom or bathroom. There are some exceptions to location restrictions for a modern condensing furnace. Check with local building officials for safety codes in your area.
If you're going to zone, you might as well get a new high-efficiency furnace and air conditioner.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him at P.O. Box 14091, Evansville, Ind. 47728, visit his website at www.onecallinspections.com or send him e-mail at d.Barnett@insightbb.com.)
