Replacing a hot water heater - need one with a heat exhanger

[tdappleman]

The hot water heater in my boat currently does not have a heat exchanger. It works really well while plugged in - but it would be nice to have hot water when on the hook or just out cruising. Question is - how does the heat exchanger get connected in? My engines are raw water cooled - is it as simple as just splicing into the existing cooling system and just adding the hot water heater into the loop or is there more to it?

 

[chris41483]

yes, you just run one of the heater lines through it from the water pump, this is the way mine is from the factory. piece of cake to do that part, actually removing and reinstalling the water heater is a different story

 

[Nehalennia]

I have a FWC(closed cooling) system. When I added my hydronic heater kit, I added new heater hose from the engine to the Hot in on the water heater and relocated to the hot in of the hyrdonic heater's heat exchanger. In the middle of that hose I added an auxillary pump to aid in circulation(keeps the water hot at lower RPMs). Then I added a new hose from the "out" of the hyrdonic heater's heat exchanger and to the hot in of the hotwater heater and then returning to the engines cooling In.
You may not need to add the aux pump but you'll want the hot out of the engine to go to the hot in of the hot water tank and the out to the engines return.
Hopefully that helps.

 

[tdappleman]

Thanks guys - I was hoping it was that easy! If getting it out is the hardest part then I can handle it! Looks like I actually have room to get it out - might need to take out one battery but it may come out after that.

 

[MikeS]

We just got rid of the big, slow heating oversized heater in my 460 and put a Eemax "instant on" in it's place. About $300 and so far (I've only tested it), so good...

 

[wkearney99]

If you're looking at something like an Attwood, the heater tank inside the square box is round. The case comes off. It's sometimes easier get in/out with the case off. There's just a dozen or so 1/4" head sheetmetal screws on it. Use a nutdriver, not a screwdriver. And have some stainless spares on hand so you're not squirming around the bilge trying to find the dropped ones.

 

[tdappleman]

We just got rid of the big, slow heating oversized heater in my 460 and put a Eemax "instant on" in it's place. About $300 and so far (I've only tested it), so good...

I wish I had a generator in order to do something like that - but then again if I had a generator I wouldn't need to replace at all. This thing actually heats up in about 20 mins but doesn't help much on the hook.

If you're looking at something like an Attwood, the heater tank inside the square box is round. The case comes off. It's sometimes easier get in/out with the case off. There's just a dozen or so 1/4" head sheetmetal screws on it. Use a nutdriver, not a screwdriver. And have some stainless spares on hand so you're not squirming around the bilge trying to find the dropped ones.

Thanks Bill - I went out and looked at it again last night and it's got quite a few rusty screws so I'll need to replace them all when I get the new one in.