I have a very old, very large Bryant furnace (circa 1938) in my basement. Last spring, near the end of the heating season, I noticed a gassy smell when the furnace first fired.
Today I had the unit examined by a technician from a local (reputable) repair company. When we turned the furnace on, his CO meter went insane as we approached the front of the unit.
Now, the trouble is that he couldn't find the source of the "leak." It seemed to him that the burned gases weren't reaching the flue properly. It could be that there's a blockage in the heat exchanger or the exhaust pipes. Or there could be a crack in the heat exchanger itself. (It's just not possible to get a full view of the exchanger without taking part of the furnace apart.)
I'm trying to decide on options. Should I just get a new furnace? Or should I pay the furnace company a fair bundle to disassemble the unit and look for a block or leak? Will exchangers that are approaching their 70th birthday even come apart, so we can look for blockage?
If a new unit is need, what's the ballpark price in the Pittsburgh region? (The old, 1938, ratings were 200,000 BTS in and 160,000 BTUs out. But several furnace folks have told me that a new unit wouldn't need to be anywhere near as robust, because newer furnaces lose less of their heat up the chimney.)
Thanks.
----------- Brian E. Clark