PRV for Calorifier

[comfortably numb]

I need a replacement PRV for my calorifier. The existing one is 4bar but I can only find a 3bar one at the local plumbers merchants. The water pump on the boat is 2bar.

 

Will a 3bar PRV be okay and if so what would be the significance if any, if I fitted the 3bar one?

[by'eck]

1 bar = 14.5 psi.

 

I'm sure that much above water pressure will be fine although the NRV in cold water feed will cause calorifier internal pressure to increase as water heats up.

 

Do you have an expansion vessel on the water outlet feed ? If so this will better keep the calorifier pressure under control and reduce the possibility of its PRV releasing.

Edited January 22, 2014 by by'eck

[bottle]

The difference will be that the pressure will be released at a lower pressure, approx 45 psi rather than 60 psi.

 

It (3 bar) will actually lower the stress on the calorifier and pipework etc. If you are getting anywhere near these pressures.

 

As your pump is 30 psi (approx) the 3 bar should not release.

 

The PRV is an emergency valve, to stop the calorifier going 'pop'

 

An expansion vessel is a good idea but not essential.

 

Your system is running at 2 bar (30 psi) the only time it will increase is when you heat the water and it expands, an expansion vessel will take up that excess.

 

If you do not have the expansion vessel, then if the pressure exceeds the PRV value then it will release and reduce the pressure.

 

There may be some water released as well so it is good idea to make sure this is piped directly overboard or into the space where your bilge pump is.

Edited January 22, 2014 by bottle

[OldGoat]

IME 3bar is the standard (or most commonly found) as can be deduced from the preceding posts.

 

Last year I had an "unfortunate" and a Very Nice Man from an Oxfordshire hire base sold me a 4 bar PRV at a nominal sum as a stopgap - 'cos they take them off their calorifiers and fit 3 bar instead - good enough for me.

 

 

[smileypete]

If you're going for a standard 3 bar one, consider getting one with a gauge:

 

http://www.ebay.co.uk/itm/1-2-3-BAR-PRESSURE-RELIEF-VALVE-WITH-GAUGE-/321290423577

 

Can make diagnosing pressure switch/expansion vessel/PRV problems a lot easier

 

See also this thread:

 

http://www.canalworld.net/forums/index.php?showtopic=61473

 

cheers, Pete.

~smpt~

[nb Innisfree]

We have 26 psi pumps and 3bar PRVs, no prob apart from PRVs actuating momentarily on rare occasions.

[comfortably numb]

Once again some marvellous advice boys so thank you. Much appreciated.

 

Some has gone right over my head as usual but I get the gist. I will tackle it tomorrow and report back if further problems.

[bottle]

The gist of all the advice is, with your set up the 3 bar PRV will be fine.