Pressure Release Valve (calorifier)

[Scubadoo]

Sorry if this has been asked before, is it normal for the pressure release valve on a calorifier to release a small amount of water when heating up (in may case say less than half a cup)? Should I consider replacing my 3bar valve, although I am reasonably sure it has always done this since new.

 

[saltylegs]

No should not leak at all. My guess is it has blown off at some time or someone has tried to drain it down via the PRV. and the valve is not reseating properly.

 

[David2452]

If it is actually blowing off rather than a constant leak then replacement may well be needed, if its leaking then try turning it over the spring a few times as you may dislodge a bit of calcuim that has got under the seat.

 

[greeny]

In a perfect world - no it shouldn't, but mines been doing it for 5yrs now, never got any worse. A few drops now and then are no problem.

 

[PCUK]

You must fit a small accumulator tank to act as an expansion tank to allow the water to expand as it is heated. This will solve the problem.

 

[clyst]

It's perfectly normal if an expansion tank is not fitted. Think about it ......as the water is heated it expands the taps are shut and the pump is locked so where does the water go ? ...... Through te relief valve . I haven't got an expansion tank but a poly hose fron the relief valve to a cockpit drain .

 

[nigelmercier]

Mine vents back into the cold water feed. Seems very sensible, so I assumed this was standard.

 

[prv]

Mine vents into a plastic bottle, apparently as originally built. Seems a bit gash to me, but since there's no expansion tank I guess the water has to go somewhere (and the bilge is too shallow to be a good option). I've just fitted an eBay float switch into the bottle, which at some point I'll wire up to a buzzer - I bet I'll forget to empty the thing otherwise.

Pete

 

[NormanS]

Mine vents back into the cold water feed. Seems very sensible, so I assumed this was standard.

It means you have no idea if or when it relieves.

 

[Ceejay]

It means you have no idea if or when it relieves.

Not sure I understand the reasoning here. I don't believe that the relief valve is there to indicate that there is a problem, more as a safety feature to prevent the calorifier becoming over pressurised and exploding.
Mine has relieved itself since new, as does the replacement, and I fully intend directing the overflow overboard this year, as it's a pain in the backside. I don't believe mine is faulty, and if anyone has one that doesn't leak they should be grateful
for that.
CJ

 

[Scubadoo]

Thanks everyone, quite a few mixed views, I think I will just change the Valve as it has been on there for 13years and only cost a fiver, just to see if that changes anything. Not changed one before, it is a case of just draining the system down or making sure there is no pressure i.e. pump off before removing the valve.

 

[Graham_Wright]

Do you have an expansion tank?

 

[Ceejay]

Thanks everyone, quite a few mixed views, I think I will just change the Valve as it has been on there for 13years and only cost a fiver, just to see if that changes anything. Not changed one before, it is a case of just draining the system down or making sure there is no pressure i.e. pump off before removing the valve.

No need to drain, as long as the system's cold and not under pressure. Some PTFE tape might not go amiss on the thread on reassembly.
CJ

 

[Scubadoo]

Do you have an expansion tank?

No I don't or should I say, I can't see to find one so assumed it wasn't fitted.

 

[PCUK]

Fit a new valve by all means and then fit the expansion tank to solve the problem. The valve is solely a safety feature. Expansion space is essential for a correctly operating system.

 

[nigelmercier]

The valve is solely a safety feature. Expansion space is essential for a correctly operating system.

Are these not contradictory? I believe that the valve is expected to open every time the water heats up, it has to go somewhere as it expands.

 

[prv]

Are these not contradictory? Is believe that the valve is expected to open every time the water heats up, it has to go somewhere as it expands.

I think the point is that if you have an expansion tank, the valve is only a safety feature. If you don't have an expansion tank, it's part of the normal operation. A tank certainly seems like the better option to me, but possibly not better enough that I'll rush to replace my leak-off system.

Pete

 

[Scubadoo]

No need to drain, as long as the system's cold and not under pressure. Some PTFE tape might not go amiss on the thread on reassembly.
CJ

Thanks Ceejay, I always use PTFE tape on plumbing.

 

[Scubadoo]

I think the point is that if you have an expansion tank, the valve is only a safety feature. If you don't have an expansion tank, it's part of the normal operation. A tank certainly seems like the better option to me, but possibly not better enough that I'll rush to replace my leak-off system.

Pete

That is what I am starting to conclude, this article was posted on another forum, seems to explain it quite well, not so concerned about the occasional discharge anymore when heated...http://www.tb-training.co.uk/17Bdomwat.html

Thanks Pete for your advice.

 

[NormanS]

Not sure I understand the reasoning here. I don't believe that the relief valve is there to indicate that there is a problem, more as a safety feature to prevent the calorifier becoming over pressurised and exploding.
Mine has relieved itself since new, as does the replacement, and I fully intend directing the overflow overboard this year, as it's a pain in the backside. I don't believe mine is faulty, and if anyone has one that doesn't leak they should be grateful
for that.
CJ

If, for example, the PRV was leaking, and passing all the time, you would want to know about it. If it is connected up to the cold water feed, how would you know it was leaking?