Mini-catalytic heater for keeping tanks warm off-grid??

I have an Olympian Wave 6 which works great on very little propane and zero battery power.

profdant139 wrote:
And ducts from the furnace are out of the question for the same reason -- that needs too much juice.

Sounds like you're under-batteried.

Rather than heating the air (or, as in the case of a radiant catalytic heater, the outside of the tank), why not directly heat the water in the tank instead?
Pull water out of your fresh water tank, circulate it through your hot water heater, and drain it back into your tank. Much more efficient use of propane. A side benefit to the way I did my hot water recirculation (so I get instant hot water in the shower reducing water waste) too.

As to using a catalytic heater for personal comfort, I love mine. But, it is an Olympian product, not the Buddy heater (which I don't like at all).

In regards to enclosing and insulating the underbelly of your trailer, here are some thoughts:
Advantage (to being enclosed and insulated):
- Warmer
- Road spray (mostly) stays out
- "Less" issue with water lines freezing
- Quieter
Disadvantage (to being enclosed and insulated):
- Initial cost and effort
- It's hard to perfectly seal out mice.
- Water will find a way in and ruin your insulation unless you take efforts to mitigate the damage (i.e.; insulation supported by the floor and/or closed cell insulation).
- When you have a water leak, not only might your insulation be ruined, but it's a PIA to get to repair the leak or do other things down there.
- Even insulated, you will still need to force some heat down there. Easiest way is to simply use a fan to force some cabin heat into the area. So I am sorry to say that, if you go this route, you will have to learn to dress like a Hawaiian in your trailer in the winter. No more parkas inside for you. So sad :C

Hi Profdant139,

I've never seen a "mini" catalytic heater. It would need to be fairly sophisticated to lite and be thermostatically controlled.

Since you are concerned about tank freezing here is what I would do.

Add an extra connection to the furnace plenum that connects to the "newly enclosed" tanks are. The valves need to be in this heated space, too.

Then add a mechanical thermostat with a 12 volt in the duct fan (at the "box" you have created). Set the temperature for about 5 c (40 f). It will cycle and draw warmed cabin air into the tanks area. For best results, have a cold air return tube on the other end of the "box".

My solution, since I have a large battery bank, was to use a dual window fan to replace the cold air return on the furnace. Fortunately, for me, this pressurized the duct work and keeps the fresh water side of the RV above freezing. The fans draw a scant 27 watts.

For the waste tanks (because some one failed to connect the tanks area to the furnace plenum) I use a 250 watt heater (Walmart $9.99) and a mechanical thermostat. I've tested this down to -27 c (-16 f).

Another possible solution is a 12 volt heating blanket fastened to the tanks (and then enclosed). These draw about 7 amps (@ 12v dc). Again, add a mechanical thermostat.

Energy use is not too high, because all we want is for the tanks to not freeze.