Leaking hot water heater question

[Jon Libby]

Well it's been a while since I've posted or needed anything about our boat. For all of the re-fit and work we've done I haven't had any real issues till now.

So I present my issue to some of the greatest minds out there.

The hot water heater sprung a leak in the fresh water side of it's circuit so anytime the system was pressurized it leaked. I have not laid eye on the leak as it's under the insulating jacket,but I have indeed eliminated all out points in the heater. It's an old round Raritan 6 gallon with the steel tank and heat exchanger. I'm sure from where the water is coming and where it drains to when no pressure is applied that I'm correct in my diagnose of a hole in the top of the steel tank, plus I have repaired, replaced many in my time both in boats and houses. We are in the Bahamas and I'm not replacing it until we get back to the states as my fall project for next season so I've removed the freshwater part of it from the boat so I could have pressurized water at least to finish the season. I've also drained the tank by disconnecting it from the circuit. It is still connected to the engine cooling system with the heat exchanger. I'm starting to wonder about running the engine for the rest of the season with no fresh water in the tank, wondering what the heat exchanger is made from and if it will stand up to being exposed to air in the tank now that no water is in it. The heater is higher that the engine so the engine coolant expansion tank is even higher in a locker. I do have the factory hose from Westerbeke to bypass and eliminate that from the circuit but I would have to move the expansion tank closer to the engine and there just isn't a great way to do that.

Any thoughts all,..

 

[Loren Beach]

Just a guess.....
but given that the heat transfer tubing inside that tank is probably metal, it should be no more bothered by engine coolant temps than the existing metal parts that carry the coolant, like the jacket and tubing in and out of the HE, or any other brass elbows or valves in that system.

Perhaps a question to the tank builder/vendor is in order.

Best,
Loren

 

[Stu Jackson]

It most likely won't hurt the coolant since that part of the circuit is still intact. However, since one side leaked, concern is not unreasonable.

The simplest thing to do is, at the engine, disconnect the coolant to the heater and install a short length of hose at the engine between the coolant pump and the bottom of the thermostat, the two places where the water enters and exits the engine on the way to the heater. That's the way the engines come from the engine factory anyway, before they put it in the boat and connect the heater.

 

[Jon Libby]

It most likely won't hurt the coolant since that part of the circuit is still intact. However, since one side leaked, concern is not unreasonable.

The simplest thing to do is, at the engine, disconnect the coolant to the heater and install a short length of hose at the engine between the coolant pump and the bottom of the thermostat, the two places where the water enters and exits the engine on the way to the heater. That's the way the engines come from the engine factory anyway, before they put it in the boat and connect the heater.

Stu,

I have that small by pass hose and thought of doing that,...but that would leave me with no expansion tank for the coolant without moving it from the locker,...which is going to be the hard part. I don't believe I could find room in the small engine room for it

 

[Pat O'Connell]

Water Tank Leak

Hi Jon
Maybe a little bypass at the tank will work for you. The tank bypass might be a minimum impact on the existing circulation and be ready for your replacement tank? Glad that you have gotten good value from your existing tank. Ours lasted about (5) years before the outside shell rusted nearly completely out. Replaced with a SS tank and it has lasted over 25 years.
Best Regards
Pat O'Connell
1981 E28+

 

[Jon Libby]

I think this idea is great, I don't have to change much and I can eliminate my worry of the heat exchanger.

Thanks all I'll let post updates as to the by pass at the water heater..

 

[Pat O'Connell]

Hot Water Tank Bypass

Hi Jon
I forgot to mention a little feature that I plumbed in with the 25 year old hot water tank... I plumbed in a permanent bypass valve for the engine/antifreeze water. When I move the bypass valve the antifreeze water does not go into the hot water tank and heat the water. The antifreeze water bypasses the tank. I don't understand cooling very well but it seems to allow my engine to run cooler on long engine trips if we are cruising and have no air. The engine used to build heat after about an hour and I would have to throttle back. I increased the size of the heat exchanger and that helped but did not cure. The bypass seems to have fixed the overheating problem.
Another benefit is that when we used to run the 15 minutes off the mooring, out of the harbor, to daysail, the engine would not heat up. Now the engine antifreeze water moves up to temperature quickly and the thermostat opens as the hot water tank does not act as a cooler when the valve is turned off. The SS tank was very hard to get back into the locker with the bypass on the side but we made it. The new ss hot water tanks look a lot smaller and easier to handle. The only down sidese I have noticed are the difficulty in getting the tank back in and the remarks the crew can make when we cruose and I forget to turn the hot water "on."
I should send a picture but the boat is covered and under the snow in the backyard.
FWIW?
Best Regards
Pat