Calorifier PRV

[Wing Mark]

Found this thread as I have a similar problem to the OP on a new-to-me 2016 boat. As there is no expansion tank in the system fitting one will hopefully solve the problem.
Before I do can anyone clarify why the PRV/ drain continues to leak long after the water has been heated? Surely expansion should then cease and the leak stop? Or could it be another issue?

Possibly your calorifier has a certain amount of air in it?
This will expand and store pressure when heated, causing the valve to dribble for a long time?
Or, it's broken.
Some valves react badly to dribbling long term, with scaling and corrosion issues.
Pressure gauges are not expensive, it might be good to know what's going on?

 

[Plum]

Found this thread as I have a similar problem to the OP on a new-to-me 2016 boat. As there is no expansion tank in the system fitting one will hopefully solve the problem.
Before I do can anyone clarify why the PRV/ drain continues to leak long after the water has been heated? Surely expansion should then cease and the leak stop? Or could it be another issue?

If the prv is defective fitting an expansion tank will not solve the problem. My calorifier and prv are 21 years old and does not have an expansion tank. The drain hose from the prv goes into a half litre container which i empty occasionally and no water comes out once the tank is up to temperature.

Www.solocoastalsailing.co.uk

 

[wingcommander]

Possibly your calorifier has a certain amount of air in it?
This will expand and store pressure when heated, causing the valve to dribble for a long time?
Or, it's broken.
Some valves react badly to dribbling long term, with scaling and corrosion issues.
Pressure gauges are not expensive, it might be good to know what's going on?

Having air in the calorifier would have the opposite effect. It would act like an expansion vessel and compress , thus helping to reduce preasure increase and thus preventing prv opening. This is basically how a Megaflow unvented cylinder operates, if the air gap is lost the prv will run.

 

[wingcommander]

Found this thread as I have a similar problem to the OP on a new-to-me 2016 boat. As there is no expansion tank in the system fitting one will hopefully solve the problem.
Before I do can anyone clarify why the PRV/ drain continues to leak long after the water has been heated? Surely expansion should then cease and the leak stop? Or could it be another issue?
[/QUOTE

Other causes of dripping PRV 's . Expansion vessel lost its charge ( if fitted re-preassure ).....faulty contaminated valve seat ( change valve)
Valve spring worn ( change valve )..... calorifier or Expansion vessel too small for the amount of heat produced by extended engine use.

Does she drip on shore power. This will be set to approx 60 degrees C . If not it may be excessive heat from engine getting water too hot for system volume, if this is the case an expansion tank should cure it.

Best of luck

 

[[3889]]

Thanks for ideas. Flushed the valve and had a bit of a twiddle and the good news is it's stopped weeping. Bad news is there is a leak elsewhere as pump is still operating periodically. Ho hum.

 

[wingcommander]

Thanks for ideas. Flushed the valve and had a bit of a twiddle and the good news is it's stopped weeping. Bad news is there is a leak elsewhere as pump is still operating periodically. Ho hum.

Could well be a leak , or doggy diaphragm in pump or as I discovered on a recent trip ...a very knackered house battery bank ,this kept the pump running trying to build up enough pressure to operate the internal switch. Was solved with new batteries , fitted on return, but I still scratch my head thinking about this one .