One tank is in my dining room against an exterior wall, no heat vent above it. The other 29 gal is in my living room,n there is a heat vent a bit above it it is sorta close to my sliding class door I will say about 3 ft away but the blinds stay closed and the door doesn't get open that much. I have the both thermomater and humomitor inside the tank, I have them in the middle on the cooler side of the tank.