(Edit: SEE OCT 23 POST BELOW FOR SEMI-AMUSING UPDATE)My trailer is so small (this sounds like the start of a joke, but it is not) that the water heater, by itself, almost puts out enough heat to warm the interior.So this gives me an idea -- the water heater, which is below one of the dinette seats, is covered in a styrofoam jacket. Ordinarily, that foam is very useful -- it means that we use less propane to keep the water hot, plus it keeps the water heater from overheating the interior of the trailer in warm weather.But if I could cut a removable flap or opening in the foam, I could get more interior heat from the water heater. It would be a "redneck heat exchanger." I would replace the flap when I no longer needed the extra heat. (At night, for example, we don't really care how cold the interior gets -- we just pile on the blankets!) So that is my question -- is this idea feasible? Is there some hidden danger that I am missing?Thanks in advance for your advice!

Would the tank be to hot for the dinette seat it is sitting under, when you take off the foam??

A great idea. You've analyzed the situation, weighed the pro's and con's and decided it might be a good solution for you. Go for it. If you find it costs too much gas, or the area gets too hot to sit near it, you can always go back to what you have now. More people should do this type of "out of the box" thinking. They'd be a lot happier and much less disappointed with the RV they decided to buy and use.

Couple of issues.......excess heat in the area where tank is located and lack of heat retention in water heater. The tank is insulated for a reason.Are you going to install a small fan to get that heat out and distribute it. Course that would cool off the latent heat from tankBut it's your trailer

I think that the "hot seat" issue is significant -- the water heater is under the seat --but fortunately, that is the seat where DW sits, and she is the one who wants it warmer! Seriously, if I do this, I would have to monitor the temp to make sure there is no fire danger. I would experiment and then undo the modification if the results are unsafe.And yes, this will result in less insulation for the tank, when (and only when) I have removed the styrofoam flap. It will mean that we will burn more propane -- but I have two tanks, and we currently use a quarter gallon of propane a day. (I have measured it.)My real question, though, is whether some of the styrofoam can even be removed at all?? Is it glued onto the tank? I would guess it is not, since there are these nylon straps that go around the tank to hold the foam on. If it were glued, the straps would be useless.If and when I do this mod, I would probably just use a box cutter to slice the foam flap, and I would probably put velcro on the outside of the flap to re-install it in warmer weather.Finally, I don't plan on adding a fan to distribute the heat -- I might cut a vent hole in the cabinet to let the heat out. There is a plywood hatch cover over the water heater -- an access panel -- and I could easily cut some holes in that, too.

Water heaters cycle but you could be causing it to have to cycle more often than it was designed to. They have thermal protection switches and pressure/temperature popoff valves. If the pressure popoff valve fails to function; they blow up. Furnaces are designed to cycle and to heat open spaces safely. On thing you might try is most campers use mechanical thermostats for the furnace/air conditioner. The DW always fussed about the heater running too long and getting too hot in the camper then getting too cold before it came back on with the old mechanical thermostat. Mechanical thermostats take a wider variance in temperature to turn off and on. Replacing it with a digital type will maintain the temp in the camper more accurately. Now the camper stays within several degrees of the setting with the digital.

Update: flap in the foam around the water heater?

westend
Explorer
Oct 24, 2013
JiminDenver wrote:
West
When I first started looking I saw dual purpose panels with a wet side under the PV side. It's what gave me the idea for a coil of hose under the panel you have now. I don't think it'll add too much weight.

Jim, the hose thing might work, I'll test it out in the next day or so.

Since I have a diversion load output on my solar controller and the batteries are completely charged, I'm still thinking of how I can use that potential power. That potential could be 180 watts for 4 hours/day and less during the shoulder hours. If I was going to heat water with that diversion the formula is Kw= gals. x temperature rise (f)/ 375 x heatup time. On a perfect day, I'd probably be able to heat my 30 gal. fresh water tank by 10f rise. That doesn't sound like much but if the water in the tank started at ambient, that would be a lot of stored heat to augment the propane heater. Also, that heat is free, basically, just using the yet unused diversion load available.

Lots of ways to get feline fur. Hitech was investigating using his excess solar to run computers and trade processing time for $$. Not too bad an idea but the payback for the capitol expense was about nine months, in the best scenario.
herbhofmann
Explorer
Oct 24, 2013
profdant139 wrote:
UPDATE

So, I am getting ready to slice into the foam -- I was all set to create a velcro hinge for my foam flap, to drill into the cabinets for vent holes, yada yada yada -- and I decide (for reasons of diplomacy and domestic tranquility) to check with DW. I drag her outside to the trailer to explain the whole thing.

She nods and says (politely), "Good idea! But how is this so different from a hot water bottle? I could boil water on the stove, fill the bottle, and put it on my lap, under my lap blanket, while we are eating dinner or reading." (That's how cold it gets when we boondock -- we often use lap blankets and wear warm ski hats while we are inside.)

I sputtered a little, disappointed that I was not going to get to do yet another "mod." But she had a point -- yes, it is a little more trouble to boil the water and fill the bottle. And it might waste a couple of quarts of water per night. But it means that the water heater will not have to cycle on and off, I don't have to cut the insulation, I don't have to drill any holes, and the heat is right where she wants it -- under the blanket -- rather than indirectly warming the interior of the trailer.

Darn.

If you are going to use "water heater" heat to warm with, why take the time to boil water? Just use the hot water out of the faucet. Of course, if you are boiling water for dinner, you have it available anyway.
profdant139
Explorer II
Oct 24, 2013
We could use hot tap water, but boiling water is much hotter - we will wrap the hot water bottle in a towel and it will stay hotter longer.
Tin_Pusher
Explorer II
Oct 24, 2013
Wouldn't think the tank temp would exceed 140 - 160 deg F, not likely any fire danger it seems to me. After all, how hot is your water?
profdant139
Explorer II
Oct 25, 2013
I am sure the tank temp is not over 150. But the real issue is whether I want to mess with the insulation, when DW simply wants a hot water bottle in her lap.

Which, coincidentally, is the solution we've adopted! ;)
Tin_Pusher
Explorer II
Oct 25, 2013
Another happy ending :)
BarneyS
Explorer III
Oct 25, 2013
With the OP stating his new, scientific, and novel solution to the problem, it is time to put this thread to bed after three pages of replies. Than you everyone for your participation.
Barney

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