Hydronic Heating a 13 Footer

[wes harris]

I have just found a hydronic heating system used to heat a 24' Airstream. It can be seen at www.solarhaven.org/HPArticle.htm

I currently own an '82 Burro 13. I would like to install a system like this one. Eventually I would like to have solar assistance, so efficiency of components would be somewhat important. I realize that there is some money involved on the front end, but it still seems cheaper(and simpler, and easier to maintain) than a furnace, & a water heater combination. Plus space is at such a premium in a 13' Burro! Heat is my primary motive here. The hot water is secondary, but a nice benefit. Is this system doable?
Do any of you have any experience with this type of heating system that you could share?

Thanks

[Chester Taje]

I think that is something to really look at
http://www.solarhaven.org/HPArticle.htm

[Rob S.]

I have been very interested in this as well. There have been significant advances in low power consumption fans and pumps since this article was written. The thing that was not clear to me was how the heater interfaced with the existing plumbing for sink/shower use or if it was a dedicated unit. I did write to the author back in August and never got a response.

Based on the drawing I figured I could construct the heating loop with a transmission cooler and a 12 volt PC muffin fan.

[Chester Taje]

If I have seen this right,I would say lines go to and from water heater and water is circulated back and forth.If you don't want heat turn pump and fan off.

[wes harris]

The water heater I was considering has a heat exchanger. Typically this is used to heat the water going down the road in an RV. In this case, you are drawing the heat out, not putting it in the tank. This is totally backwards from what the water heater, with the heat exchanger, is originally intended I would think one would want to shut off the water to the heater core completely during the summer, so provisions would have to be made for this. With a heat exchanger, I would think there would be four pipes on the water heater itself, two for water in & out, & two for heat exchanger in & out. I'm only guessing here.
The pump mentioned in the article I found on the net for $289.00. I think I could get by with less pump.(Actually I know I will. That's too pricey!) I think a 12V muffin fan will work just fine, especially in a 13.

Thanks for the feedback.

[Gina D.]

I already have a Muffin PAN..

Do I need a FAN too?

I have been in many houses with this type of heating, and one of my neighbors even installed a similar system in his driveway to reduce shoveling in the winter.

BUT, how much weight does this add and can a 13 handle it? I realize you would probably drain when under way.

Just bake some muffins when you are cold.. this'll kill several birds with one pan, er, fan..

og geez.. I give up.

[Terry D. Gwinn]

The sytem is quite easily built for anyone with a HOH heater. Things to be careful with! Heat exchanger needs to be stainless or non/lead soldered. The quality of hoh can cause corrosion problems. Also if it's a potable hoh source keeping it lead free is paramount in importance. Happy scrounging. Oh a possibility for a small heat exchanger could be the intercooler from a turbocharged engine.

T

[Chester Taje]

Whats " HOH heaters" mean?

[drew l.]

Originally posted by Chester Taje@Nov 18 2005, 07:08 PM
Whats " HOH heaters" mean?

If it had two "O"'s and one "H" it would be a H2O water heater. I think in this instance he was refering to a heavy water heater, something the Germans were working on at the end of world war 2.

[Chester Taje]

Thanks alot

[Charlie C]

I like the looks of this set up, especially getting rid of the noise of the current furnace fan. Another advantage, it can be mounted in a much smaller space, can be configured to many different space set ups.

In the Casita, I could go back to a full cupboard under the sink, and fit a unit such as this in the almost useless cupboard under the rearmost seat of the side dinette. It would also move some weight from the heavy side of the trailer to the light side. I wonder if temperature control could be obtained by putting a thermostat in line to the fan, and maybe a Hi-Lo-Off switch on the pump to increase/decrease water volume based upon severity of exterior chill.


Steve; how about some of your "Castle Pretentious" Engineering thoughts on this one!

[Byron Kinnaman]

Originally posted by drew l.+Nov 18 2005, 12:39 PM-->

If it had two "O"'s and one "H" it would be a H2O water heater. I think in this instance he was refering to a heavy water heater, something the Germans were working on at the end of world war 2.

I always thought H2O was 2 H's and one O's.

[Gina D.]

Whats " HOH heaters" mean?

Oh Oh Oh.. my tongue is bleeding..

I'll let Roger get in trouble instead...

[Brian B-P]

Regarding HOH and H2O...

While both indicate two "H" (hydrogen) and one "O" (oxygen) - and mean water - the much more common H2O form only indicates the number of each type of atom, while the HOH notation means an "H" and an "OH" group, so it provides some indication of molecular structure. This is very commonly done with complex organic (containing hyrdrogen and carbon) compounds, since two molecules with the same atomic counts could have quite different structures, and thus quite different characteristics.

Both are distinct from the HO HO heater, which keeps Santa's feet warm in the sleigh.

I'll shut up now...

[wes harris]

Here is the link for the hot water heater. http://www.ducktec.com./itm00211.htm I did call a local supplier yesterday, & he said this model ran on 220, not 110 as stated in the ad on the net. This heater should be a 110 unit for campground power, & it should be confirmed before buying.

Rob, do you have any links for low power fans, & pumps?

[Brian B-P]

Originally posted by wes harris@Nov 18 2005, 03:44 PM
Here is the link for the hot water heater...

I think a more authoritative source of information on this product would be Atwood Moble Products - Water Heaters. I haven't downloaded the brochures yet, but the the web pages mention the heat exchanger feature only in the marine version, not the RV (motorhome and trailer) version - I guess it's just an option they didn't mention in the basic information.

There is no need for a heat exchanger if the same water is circulated for space heating as used at the sink and shower - that seems to be the approach taken with the normal RV hydronic systems usually found in large motorhomes. As Terry mentioned, this means all of the space heating plumbing must be safe for potable water, and an automotive heater core seems likely to not be.

6-gallon Atwood and Suburban/American Appliance water heaters without the heat exchanger are very common in lightweight fiberglass trailers. I did notice in an earlier spec comparison that the Atwoods seem to have lower-output burners, which might not be a good thing in an integrated hot water and hydronic space heating application.

[Kurt & Ann K.]

Wes,
You've introduced an interesting topic which has energized a few of the old brain cells. I'm wondering why a system which heats the floor via loops of vinyl tubing wouldn't work. I think Gina was referring to this type of system for a neighbor's driveway.I recall seeing a diagram showing something on the floor with grooves to contain the tubing but I don't remember what that material was, or what went on top of it. I have a friend who used welding hose in his slab floor and heated about 1000 sq. feet using a Grundfos (spelling?) pump and a 10 gallon water heater. As I recall, it worked so well heating the 1000 sq. foot ground floor, that he installed a pair of floor furnace grates(one in the ceiling and another above it in the floor) so heat would rise to the upstairs. The building was kept very comfortable. The original intention, as I recall, was to use a wall thermostat to control the pump and the thermostat built into the heater cycled it as necessary. Whether that was done per original concept is unknown, but I've been in the building in the winter many times and warm floors are very nice.
I realize that not all TT's can spare the loss of even an inch of clearance between floor and ceiling, but we are not all 6'2" tall either. I believe our 17' Casita might be a candidate.
If the tubing was up to potable water standards it might work if provision were made to recirculate the water until a pressure change signalled a need to replenish consumed quantities.
More study is required, but if both domestic hot water supply and space heating could be achieved with the existing H20 heater and pump this would be a great modification. Of course, a heater which will operate on propane or 110V would only add "icing to the cake".
Thanks again Wes, for introducing the topic of hydronic space heating. Now all we need is an active experimentalist.

Kurt & Ann K.

[Brian B-P]

While most RV hyrdronic heating systems seem to use heat exhangers with fans to heat the air, I think Kurt's suggestion of in-floor heating is interesting.

Floor construction varies among our trailers, but I think it is relatively common to have nothing but a single layer of plywood between the finish flooring material (such as sheet vinyl) and the world below the trailer - that's the case for my Boler B1700, except for the fresh and grey water tanks. This is like a house, with plywood across the joists, and open space between the joists, but the frame rails and crossmembers take the place of joists.. In houses, in-floor heating is sometimes installed by placing the tubing against the bottom of the flooring plywood, then covering it from below with insulation (so the heat tends to go up, rather than into the space below. Perhaps this would work - maybe in combination with a small forced-air unit where it might be required - in a trailer?

In the case of my B1700, the tank areas could be handled by lowering the tanks by the thickness of the tubing (and filler panels of the same thickness between the tubing), which would allow heating of the whole desired floor area, as well as keeping at least the tops of the tanks warm in cool (but not seriously freezing) outddor temperatures. Since the tanks are a ground clearance problem for some of us already, a very mild suspension lift might be in order at the same time.

[Bill Abbay]

I live in a house in which I designed and installed a radiant floor hydronic system. There's no reason I see in principle why such a system shouldn't work in our small trailers.... except for the floor thickness pitfall. The gotcha here is that, in order to direct more of the heat into the trailer, a lot less needs to be kept from the rest of the planet. Assuming there is no floor insulation now, I'd say we need an insulation level beneath the tubing of at least R-7 if there is no carpet on the upside, somewhat more if there is. This means 1-1/2 in or so of styrofoam or 1 inch of polyisocyanurate. Depending on the existing trailer, this could be quite difficult to achieve, given the clearance and tank position issues already mentioned. For simplicity, I'd keep away from (more) expensive heat exchanger heaters and use PEX or copper potable water tubing.

Heckuva idea. Wish somebody would do it.

[Robert B]

Quiet warmth, what a novel idea. :11: