Truma is finally selling in the US now

If Truma could sell their propane fuel cells in the US, it would make life really nice for RV-ing, especially when combined with other products.

In theory, I could buy/rent a 100 gallon propane tank, attach it to the RV via an Extend-A-Stay system. The fuel cell would provide power to keep the batteries topped off. The hydronic system would keep the tanks and plumbing above freezing, and the furnace would keep the inside in the upper 30s. No power needed, just plug in the propane and walk off. This would be nice for keeping a rig ready to go at all times in the winter. However, if there was access to power, the system could run off of that, and if power gets interrupted, switch to LP gas.

This may not be workable in more northern climates, but here in Texas where the main worry is hard freezes at night, it would be a nice thing to have.

I agree that a domestic water heater would do a very poor job in a hydronic system- a BTU is a BTU, and RV water heaters are less efficient than RV furnaces, so with an input of 10k btu/hr you would get the equivalent of a single electric heater. In addition, the water is not hot enough for a heat exchanger (it would be fine for heating a slab though :)).
The Truma/HydroHot/Precision Temp type heat an antifreeze solution to the upper hundreds, then run a coil through that solution for domestic hot water, which results in near limitless water.

I'm skeptical. I wonder what the BTU output of a little trailer water heater actually is. Not that great, would be my guess, like 15 or 20 Amps at 120 volts. What is the breaker size for heating water with electricity I wonder?

I remember when one of my HVAC managers got the idea of heating a home with in-floor hot water using two full-size (40 gallon) electric water heaters. It couldn't do the job, because the BTU capability was only, if I remember right, 10,000 BTU's each, and 20,000 BTU's couldn't do the job when it got really cold.

If the water heater in a trailer is 15 amps, then it could produce about 5,000 BTU's, and if run on gas, it isn't likely to be much greater than the heat output from electricity.

So: if you can only get 5,000 or so BTU's out of a water heater, then you'll need further heat sources when it gets cold. My 30-ft 5th wheel needs TWO 5000 BTU space heaters when it gets down to about 30 degrees. (I can't stand my furnace, and haven't used it even once since verifying that it worked, 5 years ago.)

One final point: running the H out of your water heater may lead to scaling, carboning, oxidizing, etc and otherwise shortening the life of the heater. Trailer water heaters are quite expensive. For that reason alone, I'd opt for a couple electric space heaters.

mlts22 wrote:
Link.

I've grumbled about this before when Truma only sold their propane level meter, but apparently they are dipping more than just a toe in US waters with their Combi forced air LP gas furnace/water heater. It also has the option to work on electric as well.

Why does this matter? It means that one doesn't need as much space in a rig for both appliances, and because it works on both propane and/or electric, one doesn't have to draw down the LP gas tanks when at full hookups, but still have the furnace blow warm air on basement tanks and plumbing.

Hopefully they will start selling their VeGA propane fuel cell here in the US. If they do, the absorption fridge can be tossed once and for all.

Thnx for posting that link,Truma has some interesting very products makes one wonder why haven't I think of that?

http://youtu.be/xHKXp5B69tI

I have seen a water recirculation system that was very similar to what is pictured, except the return link went to the top of the FW tank to keep the entire cold water system somewhat warmed up. Add to that radiators for basement compartments.

Two downsides... it might be a PITA to winterize, and a six gallon water heater might not put out enough heat in the water to keep the rig warmed up.

That would work ok for a small trailer. But larger trailers need duct work to deliver to baths and bedrooms and from what the picture shows,this systems blows directly out of the heat exchanger.

Wow what a way to go. I have used hot water in the past to heat my green house in the winter months and hot water to heat the cabin area of my boat. For the green house I used a small propane water heater and automotive radiator, and the boat uses the engine cooling water and a heat exchanger like you show in the photo. I don't think a propane water heater in the RV would have any trouble keeping up with demand.

For me where our winters are not all that severe I truly think I could survive just fine with a simple HYDRONIC setup using my hot water heater only and just get rid of the PROPANE Furnace with the very loud blower setup... My propane runs us out of oour trailer - way too much heat to regulate.



One of my RV NET friends did this already is his small footprint floorplan trailer and worked like a champ in the Colo mtns.





I probably would feed my hot water through one of these AQUA HOT water heaters that has muffin type axial fans installed in it...


You could route some pex lines around the living space and use some of these wall board type heat registers


Your only problems would be to keep the hot water "hot" using propane or electric elements and the DC current drain of the 12VDC muffin type fans.

Been wanting to experiment with this idea but have never made time for it yet..

Roy ken