My Carriage C-Force toyhauler runs about a 15C difference between interior temp and basement temp when heating with the 1960's technology rv forced air furnace, so it doesn't waste excess heat to the basement.
The furnace is "35,000 btu".
When the trailer is cold soaked think warming a rock up with a hair dryer. It takes hours to come up to temperature depending how cold it is outside. Oh the air gets warm and stuffy fairly quick, like forced air does, but the moment the hair dryer shuts off the cold is felt, and the cold air blowing / roaring starts again :).
It's all done at about -12C in calm weather - basement is at 0C and interior about 15C wear a sweater furnace is running pretty much full time.
RV furnaces like to stop just long enough so they can blow that cold air on you till the burner fires ...
If I add about 8000 btu of electric oil filled radiant heat all of a sudden it's getting comfortable - which speaks to the efficiency of radiant heat (like the sun) vs forced wind like a hair dryer...
Except when the radiant heats the interior with it's nice steady warmth then the basement isn't getting heat without the hair dryer running - except for radiant passing through the floors eventually (radiant doesn't go "up" it travels in a straight line and heats materials it strikes - like heat from the sun) ...
I'm thinking about a designing a radiant living area system with separate stand alone controlled heat for the basement to hold it above freezing.
