I have a 2007 21.5' Bigfoot Trailer. Although I have the owners manual from the original owner I don't see anywhere that it has heated holding tanks. When I look at the Bigfoot web site for 2009 units (I know Bigfoot is shut down now) I see where heated tanks on the 2009 is standard.
Does anyone know if heated tanks was a standard feature on the 2007 was a standard feature? I heard an ex Bigfoot employee is a member of this site so perhaps they know??
I have a 25FB, 2008 and my understanding of how the heated tanks work is that there is a heater vent from the furnace
that blows down into the 'basement' where the tanks are. Mine then 'purges' iair nto the toilet and at the door. You could check that your holding tank area is enclosed and insulated and there is a furnace
vent feeding into it.
I would also say that if you have thermal windows
and insulated walls then by default your tanks should be heated in this manner as well.