Heating using the hot water tank.

[MtnDon]

Just an update. We wandered around CO for the past two weeks. Camped two nights near 10000 feet and had rain, wind and cold. We stayed warm inside off the heat from the water heater.

[lrrowe]

Great news MtnDon.
Later this summer I have hopes to have mine done. I believe I have all the material and process understanding to do mine alone with the in-floor tubing loops.

[bdosborn]

QED.

I was wondering when someone would work though this concept.

Well done.
Bruce

[OverTheTopCargoTrailer]

Subscribed and interested. This idea has been bouncing around the forum for years and I don't think anyone has ever done it.


Bruce

I have been doing it for years, I just fill my water tank with 120 Deg F & it works for 2 days. You can also fill 5 gal water buckets with 120 to 180 and the heat will migrate through your whole trailer. If you insulate the tank or use a cooler - the heat will be slower & last longer.

Cheers OTTCT

[OverTheTopCargoTrailer]

I think I have read all the posts in this thread, so please forgive me if this has been asked and answered...

This is really interesting using the Rv water heater for cabin heat and it makes perfect sense. Has anyone done this using an on-demand type heater? My thought is that if you had a secondary pump system, on a recirculating flow line, you would then use the thermostat to activate a relay which would in turn activate the pump. Water flowing then tells the heater to fire up. As you guys note on a tank type system, if you do a closed loop, then the feed water temp will keep rising. This would also happen with the on-demand, but I think much faster. With my little 5L, it raises the incoming water about 30-50 deg F at 3/4 heat/flow rate in 10 seconds. You could then put a high temp shut down in the circuit to cut out the burner ignition once the water got to say 150 degrees or so. It wouldn't be a pressurized system, just a free flowing pump dumping heated water back into a storage unit.

Circuit would be 1) Storage Tank - 2) secondary pump - 3) Heater core - 4) return to tank with high temp cut off on igniter, but not the pump. Thermostat turns off pump and igniter.

So, is this viable or am I missing something. I ask because I already have the on-demand and will happily add the heater system if it looks doable. Unfortunately, can't really test much on the cabin temp rise now, as it is 90 in Florida.

dave

I have 190,000 btu endless water heater, just use it to fill my water tank or some 5 gal buckets. WORKS PERFECT. Again not sure why folks here wanna complicate things.

[Shadow Catcher]

OTCT yes a continuous water heater will work, but I for one do not have one. There are advantages to a conventional water heater for doing dishes or taking a shower and when we have shore power we are using an electric element.

[daveesl77]

Somewhere back in the thread I did a prototype and did several test runs and it worked fantastic using the on-demand system. This winter I'll combine the prototype parts into a compact package, build the actual working unit and install it. Using a non-pressurized tank, a hi-lo temp sensor to control the burner and a standard thermostat to control the pump and an aluminum car heater core (new). The heater system uses the same water heater as is used in the cabin, but the heater water is on an isolated circuit so it can't backfeed into the potable water.

dave

[lrrowe]

Last week I finished my plumbing for potable water and my loop heating system. I have two nagging leaks at the pumps, but I have new parts on order to hopefully take care of them. Also last week I had 90 % of my propane work done. Today the mailman delivered the last two parts to finish that work. Tomorrow if I get home from my Dr. Appt. at a reasonable time, I hope to fire up the system and see what my results look like.

[MtnDon]

[lrrowe]

I have all my connections made and the testing is started for my hydronic water heating system for a CT.
As far as I am concerned it works. Not cheap, the way I did it, not simple either. And the real tests will be on some cold nights...never thought I would ask for a cold night.
See viewtopic.php?f=42&t=61777&start=165
for photos and reporting.

The concept has some issues and probably is not for the minimalists. It also requires some disciplines that may make it not worthwhile for others. I plan on giving it a real through test this November when I take it to my hunt camp.

[MtnDon]

Another update, another success. We spent a couple of nights camped in 38 F lows, daytime highs of 65 F. Inside it stayed at the 67 F set on the temperature controller.



I have no doubt that a tank or two of hot/warm water releasing heat into the interior works. But to my mind that means carting water that does not get used for any other purpose. That does not appeal to me.

[lrrowe]

At my lowest setting I am maintaining about a 25 degree difference between inside and out. But the outside has not been below 51 yet. I ordered my thermostat today and a spare pump.
I had not thought about the extra bulk for the radiant tank, but if you use it as your consumption water then it could serve dual purposes. It just means there is less water as time goes on. Tomorrow I will fill my ten gal under counter tank and see what happens. I am too tired to do it tonight and there is a steak on the grill.

[lrrowe]

Tried the radiant tank idea as suggested by OTTCT. Filled 10 gal tank which is not yet covered by lower cabinets with 120 degree water. AT 9PM the outside temp was 65 degrees F and inside was 81. I woke up at 1:30 with insomia and went out to check it and the outside was 61 and inside 71 including walls, floors, ceiling, ambient air and a refrigerator stored out in the middle of the floor (not plugged in).

So again I will state that as far as I am concerned, the theory works. If I was so inclined, I would prepare a spreadsheet with BTU's caculated for heating the water and for the discharge of the built of water, but I do not to take the time and energy.

The upsides are clean, noiseless and non interior gases created and so forth. I will continue to try this as the temps drop this weekend.

The downsides will be that it takes time and energy to move the water from the heater to the tank. I am concerned about the life of my "ancient" pump, the drain on the battery and for how long will the heat in the camper will support the desired interior heat. I do not want to have to get up in the wee hours of the monrning and have it too cold in the trailer and need to "stoke the fire" so to speak. I suppose another complicated timer could turn on the radiant heater and/or the fan/radiator on with a thermostat.

And what is the heat transfer rate when a cabinet is built over the tank?

Another concept could be using a timer to have the heater move more hot water to the stationary radiant tank.

Again it boils down to how much youare willing to deviate from the "KISS" philosophy?

[Shadow Catcher]

My experience is that parts left out don't go wrong (and bring spares).
This does however bring up another idea I have kicked around, and that is using an external camp fire/boiler to supply heat, which would work with your tank. The problem might be keeping things from getting too hot.

[lrrowe]

I see no reason why an outside wood stove would not work. And given enough time and thought, there should be a way to control the temperature. I am guessing this is more for extended stays. I am not home for a few days and cannot wait to try the my various heater setup in 40 degree nights.