KEN MOON: Blocking vents in unused areas will stretch your cooling dollar

By: KEN moon Special to The Gazette
July 26, 2013 Updated: July 26, 2013 at 10:05 am

Dear Ken: Do you think I should block off my basement vents when I use the central A/C? I live in a ranch-style home. - Bob

Answer: It's a pretty good idea. The dense, cold air will find its way down stairs anyway, so the basement will always be cooler. One precaution though: Don't close off more than 25 percent of the total number of vents in the house. Otherwise, you risk freezing up the cooling coil inside the furnace.

One way to stretch out your cooling dollars is to circulate that cold sump of air in the basement throughout the house. When you come home on hot days, set the fan switch to the "on" position for the whole evening. That way the cold air mass will be mixed in with the warmer air upstairs.

Dear Ken: I installed new air conditioning last fall. They put in a programmable thermostat, and the technician told me to leave it on one constant setting for maximum efficiency. Does that sound right? - Val

Answer: Not really. I have no idea what he had in mind. These so-called setback thermostats are as effective now as they are in the winter. When I'm in the cooling mode, I set mine at 78 degrees until about 4 p.m., at which time it drops down to 73. That way the house is cooled down when I return home. At 11 p.m., I go back to the higher setting.

Dear Ken: I want to move my laundry setup to the furnace room. Is this OK? Will it hurt the furnace or water heater? - Carlos

Answer: Not at all. This is a very typical arrangement. Admittedly, the furnace will get a little dirtier with dryer lint between service calls, but as long as it gets cleaned and checked each autumn, you'll be fine.

The dryer uses up almost as much air as the furnace and water heater put together, so make sure to install a full louvered door to the furnace room. If you have a door at the top of the basement stairs, it's a good idea to "steal" some air from the upstairs level. This is usually accomplished by cutting a 12-by-12-inch opening in the wall to the stairwell (just to be safe, run this by your HVAC person). Install a regular white grille cover on each side of the hole, and you're all set.

Dear Ken: We have a 60-year-old house with asbestos siding. Our homeowners insurance company wants to cancel our coverage if we don't remove it. What do you think of that? - Tim

Answer: Sounds pretty petty. There are literally millions of houses in the U.S. with this old cement-asbestos material (usually called Transite). As long as this siding is intact and is kept well sealed, it is essentially harmless. Besides, it's outdoors and not part of the breathable air space. Moreover, removing asbestos almost always creates more of a hazard than simply leaving it alone.


Ken Moon is a home inspector in the Pikes Peak region. You can email him at

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