Hi Lightfire,
I spoke to the brand manager today, Michael Creech. He apologizes for the delay in response. Your request came in over the weekend and Mike was on a flight most of today so he had not seen it yet.
Anyway, the answer is..... YES - the underbelly is heated from the forced air furnace. So when it is crucial for you to heat your tanks and lines, be sure you are using your furnace for much of your heating needs as ceramic heaters, electric fireplaces, heat pumps and such put nothing in the underbelly for you.
Jim