Originally Posted by BobGed
As previously stated your RED should have an outlet from your furnace ducting to your wet bay.
For the times the coach is parked without the furnace running I put a small 250W heater connected to a Thermo Cube that comes on at 35° and shuts off at 45° on the floor of my wet bay.
It was in the 20's last night and at 6:00 AM this morning the outside temperature was 30° and the wet bay was 52°.
Nice. That is precisely what I use as well. The same Thermo Cube from Home Depot but a slightly different heater from Amazon: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
I even put the heater on a small board as you do to keep the safety switch pushed in (because my compartment is ribbed) and to keep the heater out of any potential water.
I took my weather station outside temp sensor and put it in the rotocast wet bay. I do not have propane heat pumped in and it is about 3 degrees above the outside air temp in the 30s without the heater.
The water pump is in a different compartment which also is not heated but is foil insulated. It stays about ten degrees above the outside air temp, probably from residual heat from the fresh water tank in the same compartment.