Portable Tankless Propane Indoors? Exhaust Temp?

[Isaiah]

So I've got a crazy idea. RV water heaters are expensive. We aren't building a fancy pants glamper, just something to take a few trips per year. Existing propane hot water heater is shot, water lines are shot, propane lines are shot. Of those the hot water heater is the only expensive fix. So the question is, the old propane fridge has been taken out and now I have the vent channel sitting unused. A cheap tankless water heater is only about $100. Is there any reason I can't hang the a water heater up in that vent? Is the exhaust so hot that it would cause a problem to the plastic vent channel? Any other associated risks? Is that vent channel robust enough for this application.

[Glenritas]

If you want to die, go ahead. Hmm ... something about carbon monoxide and oxygen
depleation that will get you and your family.

That said for less then $ 330 you can get a 6 gal LP /pilot water heater or for under $460 a 6 gal LP DSI electric water heater from Camping World right now.

Do it right or don't do it at all !

Pex plumbing is super inexpensive , like 20' for $ 5 and easy to work with when using SeaTech fittings . No expensive tool needed just a straight cut and push together. you can get them from http://www.vintagetrailersupply.com

Here is my '69 Tradewind plumbing and water heater install. I used Pex and SeaTech and SharkBite fittings. The water heater is a Suburban 6 Gal LP DSI and electric . I installed it 3 years ago and still haven't run a gas line so we've been running on electric only and it recovers quickly.

I gutted the interior after replacing the axles, brakes, wheels and tires. I removed all the old systems and replaced everything except the heater. A small ceramic electric heat will heat the trailer easily.
Iused the old partitions as templets for the new prefinished partitions .
I sanded and painted all the other furniture.

[Protagonist]

Originally Posted by Isaiah

A cheap tankless water heater is only about $100. Is there any reason I can't hang the a water heater up in that vent? Is the exhaust so hot that it would cause a problem to the plastic vent channel? Any other associated risks? Is that vent channel robust enough for this application.

Several things wrong with this scenario:
1 - A residential tankless water heater is not designed to stand up to the rigors of being mounted in a travel trailer. Houses don't move and so fittings and connections designed for residential use aren't necessarily as robust.
2 - Residential tankless water heaters don't vent their exhaust through plastic. They use metal ductwork. You wouldn't be able to use plastic ductwork with any reasonable expectation of success.
3 - Residential tankless water heaters are designed to burn natural gas, which unlike propane is lighter than air. The way the residential water heater is vented for natural gas combustion is likely to allow propane combustion byproducts to build up rather than being vented harmlessly away as they should be. Also, you'd have to re-jet the water heater to account for the different air/fuel mixture required— Propane (RV) requires an air/fuel ratio of about 25 to 1, while natural gas (residential) requires an air/fuel ratio of about 10 to 1.

My recommendation is pretty much the same as Glenritas. Stick to appliances designed to burn propane and be installed in RVs, and perform the installation in accordance with manufacturer's instructions. Do not try to use residential appliances in a travel trailer.

[OTRA15]

Originally Posted by Isaiah

So I've got a crazy idea.
. . .

Exactly!


Going "cheap" here may result in someone's death IMO. For what? A false economy . . .

Good advice so far. To quote Glenritas:

"Do it right or don't do it at all."

[jdalrymple]

While not all gloom and doom here, I would stick with an RV water heater. It would be cheaper and easier in the long run.

Depending on which residential unit one chose, there are units available that use PVC venting. I have one in my house. It was factory built to burn propane.

These units require a fresh air intake to be plumbed to the outside to supply combustion air. This eliminates the O2 depletion problem. The idea here is to remove as much of the combustion process from the living environment as possible. The flame is inside a sealed combustion chamber.

An RV unit does all this by design. The entire burner, fuel supply, exhaust vent, and air supply are outside the trailer.

One could probably safely install a residential unit inside a trailer, but not by simply hanging it on the wall inside the refer space.

Hot water capacity would be another issue. Any instant water heater priced lower than an RV unit is for a single sink, not the flow of a shower and another faucet.

A unit with both propane and the electric element allows one to make use of the electricity paid for with the camp site, and use propane only when off grid.


Regards,

JD

[Al Boondy]

Isaiah
As mentioned there are propane on demand water heaters with pvc flue pipes and there are also vent free models. You hang them on the wall with no venting required.
Exel makes a ventless model that I've used as a suplemental point of use. You can hang it under cabinet near sink for instant hot water. No vent required but it may be too small for your entire camper.
The exuast from the smaller heaters is really not that hot and they do NOT produce carbon monoxide. All gas heaters/water heaters are required to have oxygen depletion sensors and they cut off fuel BEFORE oxygen levels drop to the point where carbon monoxide can be produced.
As long as you have fresh air around unit to ensure proper combustion it will work fine. Refrigerators usually have vents thru the floor anyway which is more than enough for small water heater.

[Glenritas]

Isaiah,
If your not building a fancy pants Glamper , why not just gut it and make it an aluminum tent. Think of all the room , use the bed bases for your storage , reinforce the upper cabinets and where the bathroom was make it an other bedroom.

You could then use an outdoor shower with an outdoor hot water heater along with an outdoor kitchen with ice boxes. Then just use the campground rest rooms or a port a potty.

OR you could do it right and have a nice Tradewind to enjoy

[Ralph12]

Sorry, ALL COMBUSTION PROCESSES CREATE CARBON MONOXIDE!

[Protagonist]

Originally Posted by Ralph12

Sorry, ALL COMBUSTION PROCESSES CREATE CARBON MONOXIDE!

Propane combustion produces less CO than most other fuels except pure hydrogen. And with the exception of your stove that uses indoor air, all propane-burning RV appliances burn outside air and vent all combustion byproducts to outside.

So how exactly does "combustion = carbon monoxide" apply in this case? I'm sure you had a point to make, but you're not really making it. So please provide an more information that will help the OP— and others who have the same idea who might read this thread later— decide whether to go ahead with his idea, possibly with modifications, or to back off and try something else.

I already made my position known earlier in this thread, but I welcome opposing viewpoints that are well-reasoned and well-supported by fact. It's always good to have one's assumptions challenged from time to time.

[bibbs]

I have had two cheep tankless water heaters, they don't last long and they don't always work properly. Don't waste your money on junk! Get a proper RV water heater. It will last for years and years.