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primerate84 10-16-2006 09:19 AM

hot water heater question
I just bought a 1983 Catalina 30 and the previous owner had removed the hot water heater. (Don't know why, but I would assume it was bad and he didn't want to replace it.) Anyway, does the lack of a hot water heater effect the engine cooling? I have a Universal diesel, and a friend of mine said that some engines use the heat exchanger in the hot water tank as part of the cooling system. If I need to put a new hot water heater in, what are some suitable replacement brands, models, etc. Any help is appreciated.

Tropiccafe 10-16-2006 09:23 AM

Usually hot water heaters tend to heat up your engine cooling water. Remobing it will let your enging run a little cooler. No engines that I know use the hot water heater heat exchanger to cool the engine. If it is not needed than it would be better to disconnect it.

Faster 10-16-2006 09:57 AM

The hot water heater, using engine coolant as a heating medium, will tend to slow the heating of the coolant (and the engine) until the hot water reaches the same temperature as the thermostat setting. Whether the already heated hot water tank will cause the engine to run hotter is doubtful. (there has to be a temperature difference for heat transfer to occur)

The PO likely changed it out because it had started to corrode and fail. West Marine and others carry a range of heaters, choose a stainless one that fits in the space you have available. The better ones will cost more but last longer. Most will include an electrical element for heating water with shore power, as well as the plumbing to use engine coolant.

camaraderie 10-16-2006 10:47 AM

Faster has it right! The heater in the loop will slow down how quickly you reach operating temperature but as long as your cooling system temperature thermostat is working there will be no problem. Hot water heaters using shore power usually heat the water to 120-140 degrees wheareas most diesels run at around 160-180 degress so the engine will be the "driving" factor. If you want hot water...go right ahead and buy a new heater and don't worry about your engine temps.
Oh..and a suggestion for the install. You will be running coolant lines to and back from your engine to the heater. Put in turn off valves at the engine side so in case of a leak in the lines, you can refill coolant and still run the engine with the heater out of the loop.

MBesant 10-16-2006 11:41 AM


Originally Posted by camaraderie
Put in turn off valves at the engine side so in case of a leak in the lines, you can refill coolant and still run the engine with the heater out of the loop.

Great idea. I am winterizing today and will use your advice

marty Besant
87 Newport 30
Buffalo, NY

primerate84 10-16-2006 03:07 PM

Thanks for the info guys. I may wait before I replace it to see how much demand I have for hot water onboard. In checking West Marine, they run between $500-$700 and I can think of other things I need to do before the hot water tank.

Sailormon6 10-16-2006 03:43 PM

Sometimes owners remove a water heater because it makes it difficult to get access to parts of the engine, for maintenance or repairs. They get tired of having to drain it, unbolt it and move it (while lying on their backs in a cockpit locker), just to adjust the belts on the engine or replace the impeller.

Denr 10-18-2006 04:46 PM

I replaced my 20-year-old hot water heater this spring, I would have rather had 3 root canals, that said the heat exchanger for a 6-gallon water heater held less than a quart of fluid, the water heater is a non-issue from a heat dissipation standpoint.

paulk 10-19-2006 08:24 PM

The P.O. removed our hot water heater too. We've gone so far as to rent hotel rooms for showers. Since we've had the boat about 9 years, I'd guess we've now spent (as of this season) about as much on hotel rooms as we would have spent on a new heater, (not including any repairs or other problems with the hot water on board that might have cropped up.) People anchored to leeward don't seem to notice, so we must be getting enough washing in. Last Christmas I got a sunshower. Hasn't been used yet...

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