relief / water expansion from calorifier

[Strathglass]

When I plumbed my boat I fitted two expansion vessels.

One at the cold water at the pump and a second one at the hot water outlet from the calorifier.

There is also a non return valve in the cold water feed to the calorifier.

The pipe from the pressure relief valve just goes to the sump under the engine.

When the engine heats up the water expansion in the calorifier is handled by the second expansion vessel and no water comes out from the pressure release valve.

Thus I do not have to worry about an additional hole in the hull.

The safety aspects in the case of a catastrophic failure are still covered with the pipe from the pressure release valve to the sump under the engine.

Iain

 

[ghostlymoron]

There was (perhaps still is) a regulation in the water bye-laws that states the overflow must be clearly visible. I think some modern cisterns can be made to overflow into the bowl, one of mine is coupled this way.

The default system for WC overflows is now to overflow via the siphon into the bowl. When I bought a couple recently, I did question whether they complied with the Water Byelaws and was told that they did. If they did overflow, it would be much less obvious than the old system which discharged onto my head when I exited the back door! The new ones are easier to install though.

 

[Blue5]

At present the relief valve discharges into the GRP tray under the engine sump and hence requires frequent emptying .

?

We have exactly the same problem, ours is a pressurised system and have been down the route of bottle in the bilge and looked at installing an expansion tank.

The simple solution for us, when motoring turn off the pump pressure and leave the hot tap in the sink open, any water discharges to the sink, simples and cheap.....

 

[Bav34]

Slight thread drift but you all seem to know what you are talking about.

It has always worried me that our PRV NEVER vents/leaks, and that's despite the water in the tank being way too hot to hold your hand under, particularly after running the engine.

Is it possible to MAKE it vent (as a test) by turning/pushing it a bit like the PRV on top of a pressure cooker?

 

[David2452]

Slight thread drift but you all seem to know what you are talking about.

It has always worried me that our PRV NEVER vents/leaks, and that's despite the water in the tank being way too hot to hold your hand under, particularly after running the engine.

Is it possible to MAKE it vent (as a test) by turning/pushing it a bit like the PRV on top of a pressure cooker?

Difficult to tell from the photo so I could easily be totally and utterly wrong, but that looks like a mixer valve rather than a PRV, if it is you can stop the water being scolding hot by adjusting it to mix a bit more cold as it comes out of the calorifier.

 

[Bav34]

Difficult to tell from the photo so I could easily be totally and utterly wrong, but that looks like a mixer valve rather than a PRV, if it is you can stop the water being scolding hot by adjusting it to mix a bit more cold as it comes out of the calorifier.

Thanks but yes of course we mix cold in ... it's just that the hot water is REALLY hot and it's often been in the back of my mind ... how does the pressure build up release?

From memory the red knob you can see actually spins freely.

Sorry, I've blown the piccy up as big as I dare.

(Should I mention blowing up in this thread?)


DAVID.....FORGET IT !!!!

Looked again and it does seem to have another pipe attached to it which could be the spare pipe to the (non-fitted) extra water tank.
I'll go and have a proper look.

Thanks and sorry.

 

[PCUK]

Didn't read the entire thread so apologies if this has already been said.
Fit an expansion/accumulator tank in the system and the valve will no longer open.

 

[Pagetslady]

Mine used to be piped into the bilge, so I re routed the pipe and put a skin fitting in the cockpit side and connected it to that so now if the PRV does release water it simply dribbles into the cockpit and out through the cockpit drain.
Mike

 

[AndrewB]

Find out WHY the PRV is leaking and STOP it!

Mine leaked when the pump ran, and I just let it flow through. Eventually the PRV furred up, problem seemed to have sorted itself. One day the calorifier exploded with a mighty bang throwing scalding hot water everywhere. Luckily no-one was near.

The cause was a progressive pressure mis-setting in the pump.

A pump adjustment, or a replacement PRV, is much cheaper than a new calorifier!

 

[sailinglegend420]

Didn't read the entire thread so apologies if this has already been said.
Fit an expansion/accumulator tank in the system and the valve will no longer open.

This is the only answer!!!!!

Go to the Cleghorn Waring site for tons of information on this. We have some very good brochures from them which I can't find online, but just give them a call. You may also have to match up the pump pressure with the Relief Valve pressure, and they do one-way pressure reduction valves to help as well. It took us three years to finally sort our problems!!!!

 

[poter]

PRV's & stuff

You should not be getting any water from the PRV's they are only there as exactly what the name suggests - 'Pressure Relief', (or over working pressure relief) not working pressure relief.

Your hot water pipework & cylinder are certainly ok to take the increase in pressure when your domestic water is heated, provided it is at a sensible temperature say max 40 deg C.
There will also be a certain amount of expansion relief up the cold feed line as well.

BUT you MUST insure that your PRV is working & it should be tested on a regular basis.


Poter

 

[Puggy]

My experience of PRVs is that once they trigger the often will never reseat properly again. I have my relief tube into a plastic bottle so that I can see when it has triggered and when it starts doing it regularly, a trip to the plumbers merchant is in order and I fit a new one that last for while until the process repeats... They are not too expensive..