water heater kaput

[KandD]

Our water heater is leaking like boat made of swiss cheese... so I guess it's time for a new one. I REALLY want a gas-fired on demand water heater, but haven't had much luck of finding a "boat" one (does it matter??). On-Demands are more efficient, would free up storage, and allow us hot showers on board . I don't want to install a second 30 amp supply to run an electric, plus when we start doing some cruising I'd like to have hot water away from the pier.

Thoughts comments theories musings hypotheses???

 

[Rich Stidger]

Propane-Fired On-Demand HW heater

I've done this on my previous boat. I installed a Pomona heater on the wall in the head with a six-foot flexible shower hose. It worked like a champ!

The flexible hose was the only output from the heater. In my 30' boat, I could stretch the hose to the galley sink for washing dishes. We did not have a shower sump, so showers were taken on-deck (in bathing suits so as to not scare the anchorage...) using the hose fed up through a hatch.

The pluses-

Unlimited hot water until the tank runs dry. Good efficiency, no need to run the engine for hot water. Short run of hose to the end-point-of-use.

Minuses-

The water temperature from the heater that I had would vary according to the flow rate. So I had to set the flow rate for the temperature that I wanted.

I lit the heater each time I needed hot water so that the propane would not be on and in use all the time. Lighting was easy with a grill-type of lighter.

Overall this system was a great improvement over heating water on the stove. We had no hot water heater installed and this was the only alternative to stove heating.

 

[RAD88]

Re: Propane-Fired On-Demand HW heater

I want to do the same hookup with an on demand hot water system. Did you have to vent the stack out the cabin top? Did you have to set up a pump from the water tank ? Yes I guess. Can you use the smaller propane canisters instead of the large tank?

 

[Roy10289]

I hada Nonsuch 30 years ago that had a wall mounted propane water heater. It was vented through the cabin top. Worked great and pleanty of hot water on demand.

 

[Rich Stidger]

I want to do the same hookup with an on demand hot water system. Did you have to vent the stack out the cabin top? Did you have to set up a pump from the water tank ? Yes I guess. Can you use the smaller propane canisters instead of the large tank?

My Pomona water heater did not require an external vent. I thin that if the burner input is below a certain limit, inside venting is allowable. I did mount mine just below a cabin-top hatch and I did always crack that hatch open when I used the heater.

I ran the heater and my propane stove and my propane cabin heater from an eleven pound cylinder. Looked like a flattened 20# tank. I got good life for both cooking and water heating, but the Force 10 cabin heater would tend to use plenty of propane. I don't think you cold use the small disposable cylinders that are 16.4 oz. First of all they wouldn't last very long and secondly they may not be large enough to vaporize enough propane fast enough to satisfy the input demands.

 

[Vinny]

Here is a Bosch unit that might work. It doesn't need a "Pilot". You can download the installation manual as well. They cost $459 for a remanufactured unit.

http://www.houseneeds.com/Shop/HeatingProducts/WaterHeating/AquaStar1/aquastar1600hmain.asp

But I don't know where on a 40 you would mount it. It needs a vent and it needs a fair amount of air as well. I guess if you didn't use the forward head it could be mounted on the bulkhead in there and vented through the deck. I'm afraid the vent would foul the starboard jib sheets but you could have a stainless tubing guard made over it to prevent that. Might work.

Just a caution Propane on board can be dangerous. I like Propane but you must take all of the safety precautions.

 

[KandD]

hmm, I was going to put it either where the old unit was or in the propane locker (under the starboard bench in the cockpit). We don't use the forward head, it's been removed, but have plans to make it a shower...

If I put it where the old one was I could vent it through the through-hull that I'm not using on the starboard side... I think it was for a sump pump. add a fan to improve airflow.


Side note for anyone removing an old unit.. the heater hoses coming from the engine are pressurized a little and contain antifreeze, not sea water....

 

[Vinny]

If I put it where the old one was I could vent it through the through-hull that I'm not using on the starboard side... I think it was for a sump pump. add a fan to improve airflow.

That through hull is not big enough. The vent is 5" insulated like a stove pipe. This thing burns like a furnace does, lots of heat. Besides that through hull probably gets underwater on a port tack.

As far as the two hoses they need to be coupled together or stopped off at the engine on both ends.

Download the book you might just rethink this whole project.

 

[KandD]

hmm, that is more then I can deal with... I just can't think of a good spot I could vent it. I suppose I could go electric and install a second 30 amp service to the boat... then the work would serve several benefits. If I'm underway we could make hot water the old-fashion way on the stove.

 

[Rich Stidger]

I hate to point out the obvious, but.....

Wouldn't it make the most sense to simply replace the existing hot water heater with another one like it?

Pluses-

Drop-in replacement.
No need to re-think or re-design anything.
Hot water from the engine after charging the batteries.
No propane stack venting problems to solve.
No propane lines to run.
Simple low-tech system to maintain.

 

[Maine Sail]

Water heaters..

One reason you no longer see on-demand LP water heaters for boats in the US is that of safety concerns. Paloma pulled out of the marine market years ago over some deaths. As a result Boat US, and many others, will no longer under write vessels with LP on demand heaters. I don't currently know of one that actually has any marine approvals. Excell seems to try and sell to the marine market but I don't think it carries the UL Marine approval, which is what an insurance company would be looking for.

When we were looking at Nonsuch boats many of them had Paloma's. My insurance company at the time, Inamar, would not extend coverage with that water heater. Boat US also would not underwrite with an on-demand LP heater..

Be sure what ever you get is UL Marine rated. Or, if you want to ensure insurance coverage, have a discussion with your insurance company about a specific heater and ask them to make sure you are still covered if you install it....

 

[Vinny]

Wouldn't it make the most sense to simply replace the existing hot water heater with another one like it?

Pluses-

Drop-in replacement.
No need to re-think or re-design anything.
Hot water from the engine after charging the batteries.
No propane stack venting problems to solve.
No propane lines to run.
Simple low-tech system to maintain.

Although I did point out the Bosch heater I do agree with Rich 100%. We use our boat a lot and I don't remember running out of hot water.

 

[KandD]

I thought about a straight out swap, but I figure technology has to have made some progress over the past 25 years and this would be a good time to re-design the system.

 

[Vinny]

I thought about a straight out swap, but I figure technology has to have made some progress over the past 25 years and this would be a good time to re-design the system.

But the "if it ain't broke don't fix it" rule applies. Although yours is leaking the "system" works fine.

 

[KandD]

Thread's back!

So I took a hiatus from this project to focus my efforts else where, but the annoyance of boiling water when I need to wash dishes has caught up with me.

So, I've elected the standard water-heater, what should I look for in Quality, materials, whatchahavits?

 

[Steve Dion]

Take a look at the Isotherm unit if you are looking for quality.

Raritan, Seaward and Attwood are a few others that you can look at.