Sichard
03-18-2006, 05:06 PM
I have a natural gas furnace in the same room as my crawlspace (actually in a stand-up basement separated from the crawlspace only by a partial wall of cinder blocks). I am concerned that if I seal all the vents to the crawlspace/basement that bring in air from outside the house, then the furnace will not have enough oxygen for complete combustion, and carbon monoxide will accumulate in the crawlspace/basement. My heating and air-conditioning contractor has recommended that this might be avoided by allowing one exterior vent to be connected to a dehumidifier with a Y-shaped duct, so that the dehumidier would take in a mixture of air from outside the house and air from inside the crawlspace/basement, and then blow out dry air into the crawlspace/basement. This arrangement may require a different type of dehumidifier than the SaniDry, because the usual SaniDry for the CleanSpace does not permit an intake duct connection; it only allows an exhaust duct. Alternatively, I wonder if the furnace could obtain enough oxygen if the sealed crawl/space were included in the thermal enclosure of the rest of the house by placing a register vent in the furnace air-supply duct and another one in the furnace air-return duct, to heat and air-condition the crawlspace/basement. If I did that, however, would I not be wasting a lot of energy to condition a space that people seldom visit? I have already consulted my local BasementSystems contractor about this, but I would appreciate your expert opinion, please.