Replacing a pressure relief valve

1 Jul 2009
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United Kingdom
This is my hot water tank. The cold water supply pipe comes in behind the tanks and loops up and over to come in at the top of this picture. I think I am correct in saying that it has a 2.1 bar pressure reducer followed by an 8 bar pressure relief valve. The problem is the pressure relief valve is leaking as evidenced by a steady drip coming through the tundish. I have removed the flexible pipe to confirm it is coming from the cold supply.

I am struggling to find a replacement for the relief valve and as it is designed to be attached to an expansion vessel a like for like replacement doesn't seem like the best option. Can anyone suggest something else I could replace it with?

For instance could I add a check valve and then t off to a pressure relief valve like this one at Screwfix

Alternatively would replacing the cartridge in the existing valve be likely to stop the drip? In which case does this item look like the correct part



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Are you G3 registered /Qualified? As you need to be working on unvented cylinders.
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Thanks, I didn't realise that I had to be. I'm sure you know the answer by the fact I asked the question.

Does that also extend to replacing the cartridge in the pressure relief valve?
Yes, vast majority of work on an unvented cylinder system must be performed by someone who is G3 registered/qualified. I had an incline, but you could have been newly qualified asking ;)
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Sorry, one more question before I go and call my plumber. Just confirmation that cold water supply to the tank is also considered part of the appliance. So I can work on the water system anywhere except between the first (black) pressure reducing valve and the outlet from the tank. Not that I would be doing anything on the outlet side until it reaches a tap.

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