Just thinking the other day about how any kind of combustion type heater (with outside venting), in addition to the stated efficiency, probably requires more BTUs to heat a given space v. a closed system like straight electric heat, heat pump, etc. Wondering how much the air used by the appliance (in the absence of an OAK) contributes to cooling the home down. If the house is already leaky, does it have more/less/no effect on air infiltration?
