water heater woes

[mainesail]

     
           I'm not up on all the details but the install manual says it's Coast Guard and ABYC compliant. I had an insurance survey done 4or5 years ago and of course they found a few problems but the water heater wasn't one of them.
                                                                                                                             

In order to be ABYC compliant the unit would need to be sealed-combustion meaning the intake air for combustion and exhaust are sealed from the interior of the vessel and directly sourcing the combustion air from outside the vessel. Examples of sealed combustion appliances would be the Dickinson P9000 and P12000 wall mounted furnaces where it uses a two pipe system where by intake air come in through the outer pipe and exhaust air vents through the inner pipe.

The Precision Temp units are, IMHO, very well designed & much better than the cheap Chinese junk that is out there, but without sealed combustion they don't technically meet the ABYC standards.

Some surveyors are sharper than others on noting non-sealed combustion units, so I believe fair warning is in order when we discuss LPG appliances such as on-demand water heaters.

Like anything it is your boat and you can do what ever you want on it, unless your insurer demands otherwise.

If anyone knows of a sealed-combustion on-demand water heater please let me know about it.

[KWKloeber]

The instructions state:

• All combustion air must be supplied from outside the
Boat, and all products of combustion must be vented to
outside the Boat.

I take it that doing that, it would presumably be ABYC compliant. 
The installation instructions and pics show a 2" flue, but don't show a source duct or how/where to bring outside combustion air to the unit.

Kevin, how would that be done with that unit since you're familiar with it?

ken

[scgunner]

     ken,

       I chose the aft lazeret because it's big and breathes so well, probably why the reefer compressor was located there. To vent the flue I used the existing vent on the aft starboard deck and connected them with about 3' of metal ducting. As for the intake, I just draw the air from the compartment, I imagine if you were so inclined you could rig an intake duct with a new vent on the transom but I haven't found this to be necessary.

       The exhaust duct never gets to hot to touch, I imagine you could even run the unit without the exhaust duct. Wouldn't be a very smart thing to do though, you'd be recycling warm air which would cut down unit efficiency and down the road could overheat the compartment. Removing warm air from the boat is always a good thing.

[KWKloeber]

K-

NIce.  Sounds like the way/where you installed would be the only reasonable way to be compliant. 
Although I suppose some sort of covering/hood and supply hose could be fashioned to supply outside air "directly" the unit, ducting fresh air to other than the lazarette would not be viable.

-k