I am building a house with a sealed attic; i.e., with foam insulation applied to the underside of the roof decking. Can I install a gas furnace or water heater?
When building with a sealed attic, the traditional source of combustion air for gas appliances – the ventilated attic – is eliminated. If gas appliances are installed within the thermal envelope or pressure boundary, they must be of a sealed combustion type. The solution of many builders is to use a heat pump in lieu of a furnace and to locate the water heater outside the thermal envelope. Becoming more popular are on-demand gas water heaters mounted on the exterior of the house.
