Yes, the goal is not to keep the water warm -- it is to keep it just above freezing. And I am sure that there is no way I can use electricity to generate enough heat.
But Steve's point is a good one -- don't try to enclose and insulate the whole thing. Just the fresh water tank. If I do that, my clumsy workaround should do the trick:
My crude hot water recirculation tubeI have used that system successfully down to about ten degrees above zero, so maybe it will be adequate at lower temps if I add more insulation around the tank -- right now, I just have a layer of reflectix, with a very low R value.
I have plenty of room, however, for a thick slab of high density styrofoam-type board (available at hardware stores). Gotta think about this some more.
Is it always ok to dump RV antifreeze into the black and gray tanks? Some dumps say "no formaldehyde" and "no toxic chemicals" -- would the antifreeze violate that rule? I know there is no way they could check on me -- but I am a boring person who likes to follow the rules.
