To the real estate editor: People who inquire about ways to block cold-air seepage through electrical outlets and other wall openings have an answer besides stuffing in more insulation. Mrs. James M. Dixon of Alexandria, Indiana (Energy Q and A for Oct. 26), probably has a well-insulated "tight" house from her description.
I am amazed how few people remember that a furnace is a heat pump that requires air for combustion, sending a flood of gases up the chimney as waste. That volume of air and other gases must come from somewhere. In a "tight" house the furnace literally forces outside air past storm windows and any available cranny. I fought this problem for years with storm windows so fogged or frosted we couldn't see the outside during severe weather.
Then I introduced outside air through a duct directly to the combustion chamber so that the furnace did not have to use preheated "inside" air to maintain the natural-gas fire. The same problem exists for any combustion process of heating.
This solved the fogging and seepage problem. I also divert some of that fresh outside air directly into the furnace plenum, mixing it with the recirculating air within the house.That helps keep the air fresh without introducing cold outside air through window openings, etc., besides helping to maintain the pressure balance between the warmed insulated inside of the house and the cold outside air.
Numerous "experts" were consulted before I hit upon this solution of cold-air seepage. Ellis Waldron Missoula, Montana