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colinw
colinw

Posted: Tue Oct 18, 2011 9:16am

Post Subject: water running from PRV on calorifier

Tony - can you help. I have a calorifier fitted to my boat that is supplied from both the engine and the central heating system. Cold water is supplied via a pump and accumulator. Since fitting a new (slightly higher pressure) water pump a few weeks ago, the pump will not shut off automatically, and a dribble of water is being pushed from the PRV on the calorifier. I have tried adjusting the accumulator pressure, but to no avail. I am having to turn off the water manually at the switch, or there is a risk of the pump draining the batteries.The old pump was a Shurflo (3901-0213 30psi) which had started to leak. The new pump is a Jabsco Par-Max 2.9 rated at 40psi (I went for the additional pressure, as I have diverter valves allowing for the occasional the use of an instantaneous heater)-any suggestions as to where the problem lies?

Tony-B
Tony-B

Posted: Tue Oct 18, 2011 5:05pm

Post Subject: water running from PRV on calorifier

There is a possibility that some scale has got caught on the valve seat so first of all give the top of the valve a few twists whilst the system is pressurised. This will flush the scale from the seating. However that is a long shot. I suspect your PRV opens at a pressure lower than the pump cut out pressure so the pump is forcing it open. The PRV should be matched to the calorifier so I can not really advise that you fit a 45 or 50psi PRV in case it splits the calorifier. All you can do is to turn the pump pressure down. The instructions should tell you how but if doing so will invalidate the pump's warranty it is possible to fit an external pressure switch. Tony Brooks

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