GordonThree - I will use one of these AQUA-HOT Model 200 i think it is for the main heat exchanger. This will fit in the same spot as the Propane Furnace if I get enough nerve to remove it... The Porpane heater is way too hot for my small foot print POPUP trailer floor plan and also the associated 12VDC blower is way to loud. I always tell everyone the blower sounds just like the GRRRR noise of sitting in the rear seats of the MD80 airplane. I wake up everytime it turns ON at night...
This is the AQUA-HOT heat exchanger with two axial 12VDC fans on the back of it. I used something similar to this back in my JEEP days to heat up the rear seat area... The 200 model has larger axial fans on it.
You can add additional heat zones to this idea and route the hot water around through some of these wall mounted heat exchangers. These don't have fans in them however. I guess you would need a a 12VDC pump in each zone and a different thermostat controlling the pump.
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One of the guys from up north got some floor panels that had water lines built into them. Maybe they had electric wires in the them I forget. He put these in his bath room floors.
I noticed we have had these conversations before with much of the same crowd in those discussions...
I haven't done my mods yet either haha... If it was sustained colder here I would have it installed for sure. We get by just fine camping off the power grid using a couple of those 12VDC lap heated blankets. Then just put the loud furnace on a real low temp setting just in case it gets real cold and get under the covers. The 12VDC lap heating pads do great under the top bed cover at night also. My battery alarm will wake me up to turn off the heating pads when they drop down to 11.9VDC. I like to shut everything down when the batteries get down to the 50% charge state and then will re-charge them back the morning when I am allowed to run my 2KW generator during breakfast.
Roy Ken