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Hello all.
On my PSC 34, the engine is not heating the water in the hot water tank.
It will heat when connected to shore power. Due to some hull damage repairs, I am only getting the boat ready now and have not tested the water system until now. Last fall the engine/heat exchanger loop fluid was replaced, and the water tank drained and filled with non-toxic anti-freeze as used to winterize RV plumbing.
An 1.5 hour engine run yesterday yielded no hot water but the engine seems to run fine and not overheat.
I am trying to understand how this system works. I assume the engine heat exchange liquid is circulated through the hot water tank, not the heated waste water leaving the heat exchanger. Is fluid directed to the hot water tank before the thermostat opens? Is it possible there is an valve preventing flow to the water tank? Maybe there is a mechanical or electrical pump which I am not thinking of?

Thanks for any help or ideas on how to track down the problem.
Regards, David
 

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Most likely you have air in the hot water heat exchanger. It happens anytime the engine coolant is lowered or removed. Lucky for you that your engine doesn't overheat because of it. We just finished a new engine coolant water pump last night and I had to burp the water heater line twice.
Easy to tell. one line will be warm the other cold if the engine coolant is not flowing. It can be messy if you loosen hose clamps to let the air out.

But, if your engine is sea water cooled I wonder if it gets warm enough.
 

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On my 3HM35F the fresh water coolant supply and return hoses supplying the coil in the water heater are connected to the inlet and the outlet of the engine fresh water coolant pump. Water should flow to the water heater coil whether the thermostat is open or closed. My water heater is mounted in the port cockpit locker. The coolant supply hose rises up to the heater and the coolant return line decends from the heater making it possible to trap an air bubble in the water heater coil. The engine coolant may not be able to push an air bubble in the water heater back down to the engine. That would prevent the fresh water coolant from flowing through the water heater coil. To remove the air bubble that may be trapped in the water heater coil, Pacific Seacraft installed in the port cockpit locker a quarter turn ball valve in the return line from the water heater. Opening the valve with a bucket under the outlet will let the air bubble out. Any coolant caught in the bucket can be added back to the head tank after the system cools. To avoid the possibility of burns, this would best be done before the coolant is very hot.

Bill Murdoch
1988 PSC 34
Irish Eyes
 

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My tank after 30 years died this morning along with 50 gallons of water that was in the FW tank. Alas, I am in the market. What type of tank? I cannot seem to locate your post on removal so please send that along if you can.

Keith
 

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Although hot water can be made by pushing the coolant through the heat exchanger in the hot water tank, this is by no means the only method. In my boat the engine coolant circulates through a heat exchanger. A seperate loop pumps coolant through the secondary of the heat exchanger and then through the diesel hot water heater, the domestic hot water heater and all the heat exchanfgers for heating the boat. There is a seperate pump for that loop which has to be switxched on in order for the engine to heat the hot water. There are also isolation valves to shut portions of the system down.
In other words, you really need to trace your system to see find out exactly what is happening.
 
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