Battery and gas fired water heater share locker

[RadiumRob]

I have been looking at a boat in which a domestic battery has been installed within a heads locker that also contains an "on-demand" gas fired water heater.

The combination of butane, hydrogen off-gas from the battery, and the occasional spark from the boiler ignition makes me nervous to say the least.

What do other forumites think? Would you countenance a similar arrangement on your boat?

Thanks in advance...

 

[rob2]

An interesting combination! It's not advisable, although thinking about it the rear of the 1/2/both/off switch is in my battery locker - so there's potential for a spark there too. That locker would definitely need a vent at the top for the hydrogen and one at the bottom for butane. I'm guessing most battery installations don't actually have an effective vent, but also they shouldn't have a source of sparks (I'll have to look at making a back box for my switch).

You don't say which heater it is, but if you're going to consider the boat it would be essential to go through the manual and check that the installation meets the manufacturer's criteria. I'd be worried that a heater in a locker wouldn't get enough combustion air and may therefore produce excess carbon monoxide and also fail to exhaust properly. Having said that, the heater I was considering fitting in my caravan had safety cut-outs for water flow, CO and flame failure.

I think I would only consider the boat if I could see how to change these installations.

Rob.

 

[mikemonty]

"Room temperature hydrogen gas is highly buoyant, and if not confined will rise at several meters per second. It diffuses rapidly in air."

http://h2bestpractices.org/docs/dispersion.pdf

Assuming the heads are ventilated (which would be absolutely necessary given the gas fueled water heater) I'd be singularly unconcerned about the H2 - particularly in light of the heavier, less easily dispersed hydrocarbons.
You'd need at least 4% H2 to become a flammable mix in air - I doubt you'd get enough sustained emission from the batteries to reach this concentration as it would probably be dissipating as fast as it was being generated.

Having said that - I'm not advising you either way - no-one in their right mind and in these litigation-happy days would. Note that I said "I'D" not be concerned - I might just be a nutter.

 

[pvb]

What do other forumites think? Would you countenance a similar arrangement on your boat?

It's not ideal, but I don't think it's a major risk. I have 7 batteries under my aft bunk, in wooden boxes with ducting to vents on the port & starboard cockpit coamings, so any gas can escape in most conditions. I'd be less happy if they weren't vented.

 

[RadiumRob]

I forgot to mention that the gas boiler exhausts through a duct into a cockpit locker, which must be kept open while the heater is in use.

My inclination is to remove the gas water heater and retain the battery. No hot water, but I'd sleep more soundly in my bunk"

 

[saltylegs]

I forgot to mention that the gas boiler exhausts through a duct into a cockpit locker, which must be kept open while the heater is in use.

My inclination is to remove the gas water heater and retain the battery. No hot water, but I'd sleep more soundly in my bunk"

Good idea. It sounds like an unflued or open flued water heater, I would never have one onboard and I'm a gas engineer.

 

[Modulation]

I forgot to mention that the gas boiler exhausts through a duct into a cockpit locker, which must be kept open while the heater is in use.

My inclination is to remove the gas water heater and retain the battery. No hot water, but I'd sleep more soundly in my bunk"

Sounds dreadful. What happens if you go to the pub one night, have a skinful and forget to open the locker lid? think of all that nasty stuff building up in the locker.

 

[claymore]

We took out our gas fired water heater. It was a wonderful device in terms of producing instant hot water but was quite old and had no flame fail on it. We replaced it with a calorifier which developed into an expensive project but it all feels a bit safer!