Water heater heater

[Shadow_Catcher]

When boondocking (we rely on solar), in our teardrop trailer it can get a bit nippy during cold weather.
I had been toying with a number of ideas over the last few years inspired by some one in Russia that was planing on living in his teardrop full time. My idea at the time was to use an external fired boiler running into the tear with an automotive heater core and fan.
This evolved into an idea of using our water heater (rare in a teardrop) as heat source. I posted that idea on the Teardrop & Tiny Travel Trailer forum and then started working on it.
Picked up a new automotive heater core, a 100mm computer case fan a 12V solar hot water pump a thermostat and two double shut off quick disconnects. The hose is Tygon food safe reinforced hose. All the bits and pieces are food safe and well with in the heat range put out by the water heater.
Others have tried this and it works well. The whole setup is very quiet and works well. The thread is here Water heater thread

[profdant139]

It may be true that using a water heater as a space heater is inefficient, but there are several big advantages. It uses propane, not electricity -- propane is cheap and "energy dense," while electricity is hard to produce and store. Better yet, hydronic heating is much quieter!

[Shadow_Catcher]

A bit slow to reply. The need to use the heater has not yet come up (Have been using the AC a great deal more). The inexpensive 12V solar hot water pump Tygon tubing and double blocking quick disconnects work with in the temperature range output of the water heater.

[Kayteg1]

Small heater cores are very efficient in cars as they get 180F coolant.
Typical water heater operates about 120F, so the set will give less btu.
In case you need pump for re-circulation - Mercedes is using electric pumps in their models starting from 1970's so you can find them on junk yard. Pretty ingenious pump that can last for 20 years and with magnetic clutch can take pretty big abuse.

[westend]

I read the whole 21 page thread. All of the experimenters that are using the water heater and a heat exchanger, no matter how sophisticated (PWM pump speed controllers, fan relays, plenum engineering, etc) are seeing some success from using the water heater as hydronic heaters.

I've discussed this a few times on this Forum (I know Roy B is contemplating it) and there are few experimenters. SMKettner uses a pump for water recirculation purposes and a few others have tapped into the water heater for various reasons. None have reported heater failure or any disturbance of the rest of the hot water system.

I'll probably be trying this as I do some other mods. I don't plan on a small heater core supplying enough heat to keep me comfortable in a 22" trailer (that would be awful nice, though) but as an adjunct to the main system, especially heating the forward dinette area that is more chilled than any place else.

To Shadow Catcher,
Can you give any tips or capsulize any salient points of the heat exchanger use and installation? I'm mostly looking for do's and dont's that you may have encountered, not super-accurate heat transfer figures.

[SaltiDawg]

I guess water heater rating is not known...

[beemerphile1]

I don't intend on reading a 21 page thread on another forum to get the story.

I think hydronic heating will become more common to replace the very inefficient forced air furnaces.

Here is a system that is already used in some RVs;
Alde hydronic heating

[wa8yxm]

THere used to be a home/office/shop water heater that doubled as a room heater.. Many (over 50) years ago.. I think the make was HiPoint (Actually made by Roan and Kunzl Corp in Marshall MI.

So.. I think your idea may work Not sure how well as the water heaters in RV's are not all that powerful.. but it just might work, especially on propane.

[JaxDad]

The two words in there that jump out at me are "Boondocking" and "water heater".

Water heaters are notoriously inefficient.

However being that you're talking about a tear drop trailer a couple of candles would just about take the chill off. 😉

[GordonThree]

Link not working, at least on mobile.

So you've built a hydronic forced air heating system for your teardrop trailer?

[K_Charles]

Colo Native wrote:
OK, being a former plumber for the record they are not HOT WATER HEATERS they are WATER HEATERS because if the waters hot why would you have to heat it?? Sorry had to get that off my chest.

But if the OP is referring to a heater to heat the trailer, the heater uses hot water, so it would be a hot water heater. A lot of houses have hot water heating systems.

[Colo_Native]

OK, being a former plumber for the record they are not HOT WATER HEATERS they are WATER HEATERS because if the waters hot why would you have to heat it?? Sorry had to get that off my chest.

[SaltiDawg]

I must confess, I did not read the entire linked thread!

What is the rating of the Water Heater in BTU/Hr?

Edited to remove the word "Hot."