Lon Grossman: Old thermostat may be problem with new furnace

Q: I have a newer gas forced-air furnace and when I set the thermostat at 64 degrees. the house heats up in the 70s, the furnace shuts off and won't come back on until the house feels like an icebox. What can be causing this? Do you have any suggestions?

A: I have heard of several people that have newer gas forced-air furnaces complain of the same thing you are experiencing. The problem is probably not the newer furnace, but your older thermostat. In your thermostat, there is an "anticipator," which turns off the furnace's burner before the temperature reaches your setting. The furnace still produces heat for a while, however, because the blower will keep running until the accumulated heat in the furnace drops to about 90 degrees.

Remove the cover on the thermostat. Inside you should see a small dial or scale with numbers. Set the dial to the electrical current rating of the furnace primary control. Sometimes it is noted on the gas valves, oil relays, stack switch, etc. You might want to check with your heating contractor about the proper setting or you can experiment yourself. If the furnace cycle is too long, as in your case, slightly lower the setting. If too short, raise the setting.

By the way, periodically blow the dust off the thermostat. If it has a battery for the clock, replace the battery. Now you'll be able to cool down and relax in comfort.

Q: My house is built on a slab and I find that my feet are always cold when I walk on the floors. Is there anything I can do to make them warmer?

A: If your house or any room in your house sits on a concrete slab, the floors may always be cold.

Most, if not all, insulation manufacturers, such as Celotex, Dow, Owens-Corning, Trend Products, etc. make excellent insulation panels and kits specifically designed for insulating slab floors from the exterior. Follow these simple instructions:

•Trench around the exterior.

•Clean off the foundation walls and spread on a mastic adhesive waterproofing substance.

•Install exterior insulating panels down several feet.

•Add drip edges and apply caulking.

There is also a product from the Homasote Co. called Comfort Base. It can be applied over concrete slabs and floors as an underlayment for carpet or other floor coverings. Comfort Base has an insulating R-Value of 1.2, adds only ¹/₂inch to your floor's height and can be easily installed by a flooring company or a handy person. It comes in easy-to-handle 4-foot by 4-foot sections. This product makes rooms feel warmer and will help reduce your heating bills. Contact the Homasote Co. (800-257-9491) for cost and local distributors.

Q: My bathroom has a lot of mold and mildew on the walls and ceilings. How can I get this cleaned up so I can repaint my bathroom?

A: If your bathroom looks like a set from a horror movie because of all the mold and mildew on the walls and ceiling, you still can have a happy ending.

That black, furry stuff will be facing extinction when you do the following:

•Clean everything thoroughly with a solution of one cup of trisodium phosphate (which can be purchased at local hardware stores), one quart of chlorine bleach and three quarts of warm water.

•Repeat the above process for stubborn areas.

•Rinse with clean water.

•Let the walls and ceiling dry thoroughly.

Re-clean and spray the areas with Concrobium™ (available at Lowes). Concrobium not only kills all surface mold, unlike bleach, it also kills the roots.

When repainting the bathroom, add a mildewcide additive such as M-1 Advanced Mildew Treatment (priced about $5) to your paint. A few manufacturers already add a mildewcide to their brand of paint, so check the contents on the can. A good product is Zinser's Perma-White™ paint (sold at Home Depot for around $28 per gallon.) The manufacturer claims that if you follow directions (there's always a catch) it will guarantee that mold and mildew will not reappear for five years. I wonder if it has anything like that for telephone solicitors?

Lon Grossman of Bloomfield Hills is president of Technihouse Inspections Inc., a southeast Michigan residential and commercial inspection company. Email questions to him at drdiy@comcast.net. Sign up for his blog at http://drdiy.technihouse.com.