Dear Ken: This last snowstorm piled up some snow in our attic. We had several inches for a stretch of about 6 feet from the north gable vent. How can we prevent this from happening again? Andy

Answer: I’ve got a couple of suggestions. First, cut down on the cross ventilation. The wind blowing through the attic carried the snow inside. One way to hinder this draft is to block or slow the flow of air through that north vent. For a year-round solution, attach a fiberglass furnace filter inside the vent. That will let some air still flow through, but most of the snow will stay outside.

If this results in a warmer-than-you’d-like attic this year, then you need a winter and summer solution. Simply block the vent with a piece of plywood or Sheetrock each fall. That will obstruct the wind and snow, but you’ll still have some air movement from the remaining vents.

Remember to unblock it each spring, or the extra-hot attic will heat up the house and shorten the life of your shingles.

By the way, you were lucky to have caught this when you did. For most folks, it takes up to a week before the melting snow makes its appearance in the form of drywall stains on the ceiling.

Dear Ken: I have a fresh air duct running into the furnace from outside. It gets coated with frost this time of year. Should I insulate it or block it off? Bill

Answer: This is a required combustion air source, so don’t block it until you get approval from your HVAC contractor. The rules have changed lately, so now you may be able to use a louvered door or some grilles cut through the utility room wall to get this vital air to the furnace. Again, check with your contractor to help you design these changes – and then you can completely deactivate that pesky, cold duct.

Dear Ken: I need your advice on buying an air-conditioning system for a 1,500-square-foot house. Ginny

Answer: Several factors influence the sizing of a central air system. These include the average summer temperature in your area, the compass orientation of the structure (and its windows) and the age of the building (which is an indicator of the installed insulation). You’ll probably end up with a 3-ton unit (a ton of A/C equals 12,000 BTUs of cooling per hour).

Make sure you get at least three estimates and that they include the electrical hookup and whatever modifications are required to the existing system plus all applicable permits. In other words, a “turnkey” job – complete and ready to cool. Some vendors may recommend a new furnace, too. Again it depends on the age. If yours is no older than about 20 years, you’re probably OK. On the other hand, some old furnaces may not have enough air throughput to handle the cooler, denser air created by your new A/C system.

Dear Ken: I have a bad odor in the basement, but there isn’t any sign of a sewer problem. Do you have any suggestions? Frank

Answer: Pour a small bottle of mineral oil in the floor drain next to the water heater. The water in its trap evaporates and may be letting some sewer gas into the basement. The mineral oil won’t disappear, as the water does. But since it floats, it will be pushed out and into the sewer if the drain receives a rush of water that needs to be handled.

If the smell stays with you, you may have to look for a dead animal that became trapped in the crawl space or a concealed cantilever, wall or joist cavity.

Dear Ken: My toilet bowl sometimes seems almost empty. What happens to the water? I don’t see any leaks. Kate

Answer: Sometimes it’s simply the wind. When air blows across the plumbing vent on the roof, it creates sort of a vacuum in the pipes. That can draw water up and out of the bowl into the sewer.

Alternatively, the toilet could be siphoning. If any foreign material – such as dental floss – is hung up inside the trap, water can gradually leak up and over the rear of the bowl. If that’s the case, you’ll have to remove the toilet from its anchors and investigate.

Ken Moon is a home inspector in the Pikes Peak region. His radio show airs at 9 a.m. Saturdays on KRDO, FM 105.5 and AM 1240. Visit www.aroundthehouse.com.