Water Heater Leaking

[pateco]

Last night while motoring to a waterfront restaurant for dinner, I noticed the bilge pump kick on more than once. Boat is normally dry below, so I knew something was wrong. Went down below and had water on the sole in the Galley running from under the cabinet in the sink area. First fear was sink drain thru hull, but that looked good and was dry. Then however, I looked further back in the sink cabinet to where the water heater lives in the front end of the starboard lazarette. Water was dripping out of the bottom of the heater. I checked the hoses and connections, and they were fine. So I think the heat exchanger in the HW Heater has failed, and since I have a Yanmar 2GM20, I am leaking Raw water engine coolant into my bilge. I need to buy a Barb fitting, and bypass the heater ASAP. and then I need to decide If I am going to replace it, and if so with what. The raw water heat exchanger never did anything to heat water in the water tank, so what small heater would you suggest to replace it without a heat exchanger?

 

[Stu Jackson]

Three choices, basically, in the six gallon range:

Kuuma - a knockoff and even cheaper version of Seaward - not recommended

Seaward - good lower end of line - shop around online prices vary widely - I got one for $260 2 years ago

Isotherm (or Isotemp - I keep forgetting) - top of the line, you pay for quality, much better insulation, comes with a temperature mixing valve on the hot water out, highly recommended

 

[woodster]

They make one in the isotherm brand called Basic
And I can't remember for sure but it comes in 4 gal and up

 

[pateco]

Looking at this one Super 900 Series 0.5 GPM (3 kW/110V) Tankless Electric Instant Water Heater

Plastic Copper and Brass construction with no Heat exchanger from the engine.

 

[Peggie Hall HeadMistress]

I wouldn't use brass on a boat! Bronze, yes...but not brass.

 

[Don S/V ILLusion]

You will need one hell of a battery bank

Looking at this one Super 900 Series 0.5 GPM (3 kW/110V) Tankless Electric Instant Water Heater

Plastic Copper and Brass construction with no Heat exchanger from the engine.

 

[pateco]

You will need one hell of a battery bank

No generator on board, so no hot water away from Dock/Shore-power even with the existing heater since engine heat was not sufficient.

 

[Capt jgw]

Back when I worked at West Marine e had an electric tankless water heater in stock. I think we sold it and had it returned three times before we sent it back to the warehouse. They said it wouldn't heat water flowing at anything faster than a trickle. With higher flow the water didn't stay in the heater long enough to get hot. Different model than this one though.
I hear the shoreside gas demand heaters work well, but I don't think there is a marine version.

 

[Craig Cook]

Engine heat was not sufficient? I find that very odd. All of our boats with hot water tanks/heat exchangers warmed the water in the tank in a matter of 15-20 minutes, got it plenty hot for dishes or showers? Just speculating but maybe there was something wrong in your tank before it became really obvious? We had the hot water tank fail on our Island Packet, first it was leaking out the bottom a little, then it was leaking coolant out the bottom so we knew the heat exchanger had failed as well. That was a 2GN20F though, the coolant was green antifreeze. The end of this story is that trying to find a hot water tank with the hose location and configuration to match the original was very difficult. They seemed to be out of stock all over the country so we ended up with exactly the same brand tank that failed for us.(Seaward). I figured if it lasted 25 years before failing and the new one lasted another 25 the boat would be long gone..........and it is.

 

[pateco]

Engine heat was not sufficient? I find that very odd. All of our boats with hot water tanks/heat exchangers warmed the water in the tank in a matter of 15-20 minutes, got it plenty hot for dishes or showers? Just speculating but maybe there was something wrong in your tank before it became really obvious? We had the hot water tank fail on our Island Packet, first it was leaking out the bottom a little, then it was leaking coolant out the bottom so we knew the heat exchanger had failed as well. That was a 2GN20F though, the coolant was green antifreeze. The end of this story is that trying to find a hot water tank with the hose location and configuration to match the original was very difficult. They seemed to be out of stock all over the country so we ended up with exactly the same brand tank that failed for us.(Seaward). I figured if it lasted 25 years before failing and the new one lasted another 25 the boat would be long gone..........and it is.

This is a Raw water Cooled 2GM. No antifreeze, no on-engine heat exchanger. Raw water output from engine block was passed through HWH to attempt to heat water before returning back to the mixing elbow. Since this cooling system is not recirculating antifreeze/coolant, and is instead pulling cold raw water, the output from the engine while warm, was never hot enough to heat the water in the HWH.

I bypassed the HWH with a barb fitting, and the leak has stopped. I now have a dry bilge under the HWH.

I don't normally run the pressurized water system on the boat, ( maybe turned on for 10 minutes once every couple of months),but I turned it on to see if that side of the HWH system was also leaking, and it was. So I have also bypassed the HWH for the Sink/Shower water.

Now I just need to remove it entirely, and figure out what if anything I am going to do to replace it.

 

[Capt jgw]

Since you can't heat with the engine, an under counter home type water heater should work fine. Not marine but out doesn't need to be. As long as it's not getting salt water dripped on it, corrosion shouldn't be much worse than in a house. A marine unit would have a stainless shell, but it would cost three times as much and have a heat exchanger you can't use. And it sounds like it was the lining that failed on yours, the home one wouldn't be any different. I used one for years on one of my outboard powered boats and had no problems.

 

[kloudie1]

The problem with the GM series (raw water cooled) is that you have no access to cooling water before it gets tempered with cold bypass flow. The water from the thermostat pipe is less than 90F usually. To fix that, you can pull the thermostat housing from the front of the cylinder head and drill and tap it for a water outlet to the water heater. That water will be at the temperature of the thermostat set point (or close to it) and after leaving the water heater, it can be returned to a tee just before the mixing elbow. The older QM series Yanmars were built that way and they heat water just fine when hooked up correctly

 

[Capt jgw]

I had a 2GM on a previous boat and wondered why they didn't hook up the water heater even though the raw water siphon break was right next to it. So I hooked it up. Didn't work. Now I know better.

 

[pateco]

After more thought, I think the tankless draws too much power. What about something like this Waiwela Wm-6.0 Electric Mini-Tank Point-Of-Use Hot Water Heater (6.0 Gallon)

6 gallons, 120V and only 12 Amps. $159 + Freight