propane on demand water heater

[genieskip]

I am trying to find a small propane on-demand water heater. Everything I find on the internet is big (for an apartment or a house) and I haven't been able to locate one made for boats/RVs. My water heater is shot and I have to replace it but I dont spend a whole lot of time hooked into shore power and try not to motor too much so the standard water heaters aren't good for me. I also really like the concept of tankless on-demand heaters. They make them for camping, but they can only be used out of doors. I think I might have to go out of the US market for it.

Anyone have a lead?

[US27inKS]

I found something a few years ago when I was shopping for a water heater. If I remember correctly the on-demand systems were fairly expensive, which is why I got a standard marine electric heater.

Here's what you're after:
16L 4.23 GPM Propane Gas TANKLESS WATER HEATER - CAMPING - RV - TRAVEL TRAILER & More

[lshick]

You might have a look at the diesel fired units such as Espar and Webasto, originally made to keep truck engines from freezing up in European winters. They're quite compact (the heater unit itself is the size of maybe two shoeboxes, plus the tank itself), and draw little juice (maybe 8A for the 10-15 minutes it takes to make water uncomfortably hot).

If you go after the propane unit, make sure you understand issues like venting, carbon monoxide buildup, and potential for explosion in a boat. There may be a reason why the units are not approved for marine installation.

[paulk]

One of the reasons they might not be overly available is that they might be very dangerous to use on a boat. Several deaths in recent years have been traced to people having problems with their gas-fired hot water heaters. Pilot lights go out and the crew dies as gas fills the bilge. (This has happened several times.) Boats blow up when someone rigs the pipe to avoid an annoying safety feature. Fumes and gas concentrated around the transom knock out swimmers and cause them to drown. To say nothing of the issues when you heel over while doing dishes and the flame burns something you wish it didn't- like a fuel line. Diesel might be a safer fuel to use, but don't know much about on-demand diesel water heaters.

[mitiempo]

I've owned and used them in the past and they can't be beat for convenience. Mine was installed on a bulkhead above the stove just under the cabin top through which it vented. I doubt your insurance company will like the ones with a pilot light though. One possible solution would be to install it in a locker that is only vented outside the boat like a propane locker. Not the same one the propane is stored in though. There is one with no pilot light that looks pretty good. Here's the link.Gas Water Heater
It has electronic ignition and has no pilot light. The flame when in use is just below a horizontal radiatir like panel through which the water travels. Very convenient as you dial the temp you want and no cold mixing is required at the tap.
I have never heard of a diesel powered instant water heater - doubt they exist - at least in a size for a boat.
paulk
Why would fumes and gas concentrate around the transom? And what do those swimmers do when near the exhaust of a running generator? That's not very healthy either but best not to tread water near any exhaust I guess. The Paloma type instant gas water heaters vent through the cabin top or side right beside the unit.
Brian

[xort]

You might want to check with your insurance co to see if they will cover you with this system aboard

[Jeff_H]

The first of the modern generation on-demand hot water heaters was a marine version of the Paloma on-demand hot water heater. Most of the small portable on demand hot water heaters are a variant of the Paloma. These were originally intended for shore side use and it is my understanding that the only change made to marinmize them was to add automatic shut offs at high heel angles.

The problem with almost of these camper and 'portable' type heaters is that they direct vent into the interior of the boat. The real problem with that is the risk of carbon monoxide poisoning which seemingly routinely was killing people until the word got out about the dangers of these system.

Real marine on-demand hot water heaters are pretty expensive since they typically have exhaust and make-up air flues that intake and vent to the atmosphere, plus all of the automatic cut offs associated with any modern propane device.

Jeff

[mitiempo]

Jeff is right, but it's not that hard to deal with. I was working on a boat just the other day with a Paloma and it exhausted outside. I don't have a pic but it's a deck fitting like a diesel or propane cabin heater. As far as oxygen depletion, it's the same as any flame from the stove or heater and should be treated accordingly.
Brian

[Waltthesalt]

I've got a Wolter about 15 years old. Wolter was the US manufacturer of a tankless propane heater designed for boats. It's compact and efficient but uses a lot of air and exhausts a lot of fumes. It will exhaust into the cabin if the vent pipe is blocked. Properly installed and operated the Wolter worked well. They went out of business when there was a death/lawsuit due to improperly vented cabin. Even if you could find one parts would be difficut to find. Paloma from Japan followed Wolter in the market for demand propane boat heaters. They burned cleaner, were a bit larger and were very popular. If Poloma is still making them that would likely be what you may be looking for. I haven't been able to find them on Plaoma's web site and heard that they may have stopped selling them in the US and maybe elsewhere, probably for the same reasons that Wolter went away. There are tankless propane heaters made for RVs like precision temp (I think). You may want to google that.

[Pamlicotraveler]

I wouldn't have one. I would love to at home becasue they are cheaper to operate, or so I've heard, but they would make me uncomfortable for safety issues on a boat.