Who;e Hpuse Fans and High efficiency Furnace

[Annie-Laurie Hunter]

In a house with a whole house fan and a mid efficiency furnace there should be a lock out switch so the whole house fan can not operate when the furnace is operating.
Does the same rule apply with the high efficiency furnace with both an intake and exhaust to the outside?

Annie-Laurie

[Gunnar Alquist]

Annie-Laurie,

If you are referring to a furnace where an intake pipe is extended to the exterior to supply air directly to the burner, then there should be little chance of backdrafting. However, if there is a water heater inside, then there is still a potential of backdrafting.

[Annie-Laurie Hunter]

Thanks. There is a water heater.