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Tim JA
Tim JA, HVAC Technician
Category: HVAC
Satisfied Customers: 2430
Experience:  Owner at Self-employed
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I think my pressure relief valve has gone wrong, pressure

Customer Question

Hi i think my pressure relief valve has gone wrong, pressure going down gradually and dripping out of pipe on external wall
JA: What's the brand and model of your HVAC unit? How old is it?
Customer: Its a worcester bosch greenstar 28i junior
JA: How long has this been going on with your Bosch unit? What have you tried so far?
Customer: Tried topping up pressure thats all, noticed pressure dropping for ages never really thought much of it
JA: Anything else we should know to help you best?
Customer: No
Submitted: 12 days ago.
Category: HVAC
Customer: replied 12 days ago.
One thing is how they would replace a PRV when all pipework is boxed in behind tiles
Customer: replied 12 days ago.
I have pictures of pipework and boxing but there is no way of getting to back of boiler where i believe the prv sits without removing tiles. Can a prv be replaced from opening boiler and going through that way
Expert:  Tim JA replied 12 days ago.

Good evening, and welcome to the Technical section in JustAnswer, an independent paid question and answer platform that matches customers' questions to experts in various skills. My name is ***** ***** I'll be happy to help you today.

The answer to your question is that on this boiler access to the PRV is gained from within the boiler casing.

If a service is overdue then I recommend that you get the boiler serviced, and when you book the engineer to come ask them to come prepared to test the EV (expansion vessel). The reason I say this is because if the EV has lost its pressure then the PRV will probably open again and you'll be back to square one.


There's no time pressure on this topic - it will stay open to you for many days, and you can reply at any time. I will be away from my desk sometimes, but will respond as soon as I can.

Customer: replied 12 days ago.
Hi, funnily enough my boiler was serviced two days ago, he asked if it lost pressure i said yes and he said "thats not right " and wouldn't give me any more info than that... british gas for you i suppose... i have somebody coming out saturday, I was just concerned they would need access from beneath the boiler. Thanks for your response
Expert:  Tim JA replied 12 days ago.

You're welcome :-)

IMHO he's quite correct to say "That's not right", because it isn't right. Since his remit was to service the boiler, he shouldn't get involved in hunting for the cause of pressure loss - it could potentially be from anywhere in the system.