Leaky Calorifier Valve?

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Slipperman

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Ever since I have had my boat I have noticed that a small amount of fresh water appears behind the engine and adjacent to my small calorifier. There are no obvious leaks from either pipe connections or the calorifier itself, but there is a small spring loaded relief valve which spurts out water if you touch it. The small amount of water has not worried me up till now, but recently I seem to get more to the extent that some water is finding its way into adjacent bilges from which it is difficult to extract except by removing floor boards, the engine box etc.

The small relief valve does not seem to have any adjustment on it, and I wonder what has caused it to leak more, if indeed this is the cause. I seem to get most water when the boat has been heeled over, and of course that is when it tends to find its way into inaccessible places too. Any ideas how I can reduce this leakage? I did wonder about leaving off the electric fresh water pump except when I need to use a tap (usually the switch is made as soon as I switch on the boat electrics, and then stays on throughout). Would this make any difference do you think?
 
The pressure relief valve on calrifiers is recognised as a maintenance item. I had to replace mine earlier this year.

Available from good plumbers merchants for about a fiver (defintely under a tenner). Just unscrew and replace.

Until that point you correctly guess that it's good practice to turn the electric pump off when under way, but even when in the marina it eventually keeps cutting in regularly enough for you to get fed up and replace it.
 
I think you will find that its just doing its job as the water heats up it raises the pressure in the calorifier and the pressure relief operates to safeguard it.Most people fit a small pipe from the valve and take it to the engine room breather opening.
 
Could be the relief valve spring on the calorifer has got weak or
Could be your expansion vessel air side has deflated so that as the water expands with heat the water has nowhere to expand into and thus pressure rises and the relief valve lifts every time.
If you have water form the relief valve when the calorifer is cold and the system pressurised then the relief valve is the first item to check. If it only happens when the calorifer gets hot then the expansion vessel is the first item to check.


You might need a few pumps of air into the expansion vesel airside schrader valve and a new relief valve if the seat and spring have worn due to the lifting everytime the water gets hot.

Brian
 
Slipperman said:
Ever since I have had my boat I have noticed that a small amount of fresh water appears behind the engine and adjacent to my small calorifier. There are no obvious leaks from either pipe connections or the calorifier itself, but there is a small spring loaded relief valve which spurts out water if you touch it. The small amount of water has not worried me up till now, but recently I seem to get more to the extent that some water is finding its way into adjacent bilges from which it is difficult to extract except by removing floor boards, the engine box etc.

The small relief valve does not seem to have any adjustment on it, and I wonder what has caused it to leak more, if indeed this is the cause. I seem to get most water when the boat has been heeled over, and of course that is when it tends to find its way into inaccessible places too. Any ideas how I can reduce this leakage? I did wonder about leaving off the electric fresh water pump except when I need to use a tap (usually the switch is made as soon as I switch on the boat electrics, and then stays on throughout). Would this make any difference do you think?
Click to expand...

I had this leak this year: at first I thought it was a leak from the aft water tank, but eventually found it was the temperature/pressure relief valve on the calorifier. The leak became quite bad - gallons of fresh water going into the bilges.

I ordered a new identical valve from ITT Cleghorn Waring, and fitted it. The leak reduced slightly but continued, so I assumed it was the water pump pressure cutout switch faulty - ie giving too much pressure. As I could not get just a new pressure switch for the pump quickly locally, and the boat was in use, I fitted a complete new water pump, and still the valve on the calorifier leaked.

I then phoned ITT from whom I had bought the new valve, and they sent another FOC. This one has fixed the problem.
 
If it doesnt leak when water is cold and the pump has built up the pressure but leaks when its hot its 90% likely that the relief valve is doing its job,as the water heats up it increases the pressure in the tank and causes the PRV to vent.Pumps are usually set at approx.2 to 3 bar and PRV are set at about 4bar.My last 2 boats have always vented when water gets hot.There is a vent thro. the engine room breather slots in side of hull.
 
It really shouldn't leak, and while it has to do with pressure there shouldn't be that much to make it leak, which means it was selected for too little pressure. They come in different pressure ratings.

Also once they start leaking they tend to keep leaking, and many times very small amounts of gunk can clog the closing of the valve from the spring return.

When the water is hot, flip the spring a few times.

If it keeps leaking, just buy a new one.
 
Slipperman said:
Ever since I have had my boat I have noticed that a small amount of fresh water appears behind the engine and adjacent to my small calorifier. There are no obvious leaks from either pipe connections or the calorifier itself, but there is a small spring loaded relief valve which spurts out water if you touch it. The small amount of water has not worried me up till now, but recently I seem to get more to the extent that some water is finding its way into adjacent bilges from which it is difficult to extract except by removing floor boards, the engine box etc.

The small relief valve does not seem to have any adjustment on it, and I wonder what has caused it to leak more, if indeed this is the cause. I seem to get most water when the boat has been heeled over, and of course that is when it tends to find its way into inaccessible places too. Any ideas how I can reduce this leakage? I did wonder about leaving off the electric fresh water pump except when I need to use a tap (usually the switch is made as soon as I switch on the boat electrics, and then stays on throughout). Would this make any difference do you think?
Click to expand...

A lot of systems have a one way valve preventing the hot water from going back to the cold tap. If there is no expansion tank on the hot side, the safety valve will leak/ weap etc,if it did not it would split the calorifier, from pressure as the water heats.

easy soloution , remove the one way valve. done it on 2 systems without ill effect.
 
i had a similar problem to the OP. After replacing the Pressure relief valve it still leaked. I then inserted an accumulator on the HW outlet from the calorifier before the tap - it still leaked.

Eventually I replaced the main pump and it finally stopped leaking - obviously the pressure sensor/switch was faulty. Next time I have this problem this is where I'd start looking!!!
 
Many thanks for replies so far. I will use the info provided for some more investigation this weekend. My system has an accumulator on the cold fresh water side, and I have not heard the fresh water pump working to keep the system charged except when drawing off water by using a tap. So I would be surprised if the system was over-pressurised. It sounds as if the relief valve may have weakened, so will investigate removing it and replacing.
 
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