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

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.

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

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.

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

Enclose a gas heater inside and underbelly

Not what i consider a good idea

12v heat pad?
Ventilation to bring heat from inside trailer into the underbelly?
More battery for the heat pads?
Lamp heat run via thermocube control? (Didn't PT do this?)

I am not afraid of LP
I have heated campers using the oven, the stove top, the furnace, and cat heater, and blue flame, and with portable camp stove

But i would not enclose a heater, out of my sight in the underbelly

Hi MrWizard,

I did not do a lamp heater--but have used 120 volt heating pads on a thermocube. The problem was just not enough watts to get enough btu's

Not for longterm, but you might experiment with those chemical handwarmer things. They come in several sizes from toe to torso sized, make heat for 10 hours, and don't cost much. I put one by the water pump and one by the pipe that likes to freeze; both are inside the RV, where it is usually only 10 degrees warmer than outside. They worked great on my coldest RV night ever, about 12 degrees outside. I did forget the exterior water drain valve and it froze and burst. Oops.

For longer term, maybe a very small, like 5W, incandescent light bulb?

More batteries would be one possibility, I guess -- I already carry two group 31s, and the trailer is so small that there is just no room for more of them on the tongue.

And Steve, I already have a hot water recycling system that I cobbled together -- it is pretty crude, but it gets the job done. But I would rather have a "set it and forget it" infrared heater underneath the tank.

The fact that none of the experts have said "sure, go ahead, put a radiant heater underneath," tells me that this is probably not a winner.

Don't laugh but we have solved a few problems for people using rope light. Normal heat tape uses 18 watts per foot which is way overkill for an insulated tank compartment. Rope light (not the LED type) is 3 watts per foot. You don't need much battery and solar capacity to supply that kind of load. Take a 10 foot piece and locate in the insulated tank enclosure and along any more exposed spots. If properly enclosed you would be surprised how warm it gets in there. Use a remote wireless thermometer to keep track of things. It may not work for you but we have solved a few problems for friends using this approach.

hope this helps.

John

Hi John and Angela,

Good on thinking "outside the box". I was thinking of old incandescent Christmas tree lights, but those are becoming hard to find.

profdant139,

I have used a radiant heater--but it was 120 volt. I've used it to thaw out the pass through storage hatch--which is where my normal cord storage is.

The only radiant heater I would use unattended would be an oil filled 120 volt unit with a thermostat.

With 2 group 31 my best guess is that 12 volt DC fans would be a "breeze" to operate.

Warming the air electrically while boondocking is probably beyond what is possible. You have about 1200 watt hours to play with if the battery bank is kept warm.