Hot water heater overheats from engine

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Mar 6, 2005
33
Hunter 310 Lake Canyon Yacht Club, Texas
Have a 2000 310. When I run the engine for a more than a short time, it seems to circulate too much hot water through the water heater. After a while the safety valve on the water heater will release so my pump starts to run. Eventually, it would drain my fresh water tank. The safety valve is probably a bit weak but if I turn on the hot water during this time, it is very hot. Much too hot for the boat. Is there some type of thermostat that regulates how much water is circulated for the hot water heater?

The engine itself is not over heating and runs just fine.
 
Mar 12, 2008
557
Jeanneau 49 DS San Pedro, CA
Sounds like your pressure relief valve is bad and opening up. It is not unusual for a little water to be released, but it shouldn't let that much out. Try changing the PRV and see what happens.

Even with a new PRV, there seems to be a little water leaking through. I find about half a gallon leaks through every 20 hours of engine run or so.
 

jtm

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Jun 14, 2004
312
Hunter 28.5 Dataw Island, SC
besides the PRV, see if there's a water heater side thermostat that is not operating correctly.
 
Feb 6, 1998
11,701
Canadian Sailcraft 36T Casco Bay, ME
Re: Catalina Cost Cutting

Have a 2000 310. When I run the engine for a more than a short time, it seems to circulate too much hot water through the water heater. After a while the safety valve on the water heater will release so my pump starts to run. Eventually, it would drain my fresh water tank. The safety valve is probably a bit weak but if I turn on the hot water during this time, it is very hot. Much too hot for the boat. Is there some type of thermostat that regulates how much water is circulated for the hot water heater?

The engine itself is not over heating and runs just fine.
I have been complaining about this for years!! I have even written to ABYC and spoken with Eric Johnson personally to try and wake people up and make this a standard. Sadly it is still NOT a standard so builders can continue to scald and burn people to save a buck......:cussing:

NO boat builder should be allowed to ship a boat with engine supplied hot H2o without a TEMPERING valve, yet they do!!! It is flat out unsafe and would NEVER, EVER be allowed in residential plumbing.

Think about it. Your engine runs at 180 degrees +/- if you run it long enough the hot water will get to....180 degrees! Without a tempering valve (a T&P is NOT a tempering valve) there is NO WAY to regulate how hot the water in teh tank gets. The T&P valves on most all water heaters are rated for 210f and 150PSI.

Sadly for me the T&P Catalina originally supplied was a 150 degree unit, not PSI, this was a 150 degree relief at 150 degrees, which I don't even know how or where they found one. Mine blew off all the time..

I changed it to a 210F T&P plus added a tempering valve. The other thing to be very cautious of is the cheap clear PVC hose Catalina uses is only rated for a max of 150f. I had the hose actually get so hot it blew right off the outlet of the hot water heater and we lost all our water into the bilge miles from any source of fresh water..:doh::doh::doh: Thanks Catalina!

Both my wife and I scalded ourselves numerous times before I got around to installing a tempering or mixing valve. You'd think you'd learn but you just don't expect 180 degree water out of a tap, and shouldn't..

This is yet one more example of how many builders choose to cut corners, save money, and screw over the customer. We have a toddler and 180 degree + hot water is dangerous, simply unacceptable and can literally cause second or maybe even third degree burns!!

Add a tempering valve ad check the temp rating of the T&P!!!!

Rant over...:D
 
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