Installing a new PRV on a Vaillant Combi

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Installing a new PRV on a Vaillant Combi

Post by Dante22 » Tue May 29, 2018 2:34 am


I have a vaillant turbo max boiler which loses about 1/2 bar pressure over the space of 3 weeks. I have checked and found that the PRV outside is leaking. The expansion vessel appears to be fine (there was no abnormal pressure rise when the heating was on) so I don’t think this is what’s causing the PRV drip. No other leaks appear to be present around the house/radiators etc.

I’ve also tried to flick the PRV knob a few times to try dislodge any debris, but the leakage outside continues slowly. I’m assuming the valve is knackered.

I’m planning to install a new valve. I was reading online that I just have to drain down the boiler, and isolate the CH flow/return pipes under the boiler, and then remove the valve.

However, some people have said that, when messing with the isolation valves, if they haven’t been touched for a very long time, are prone to leaking.

Is this correct? If I do encounter a leakage at those valves when isolating, what can be done to stop this, as they are just small screws?

Thank you for your help!
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Re: Installing a new PRV on a Vaillant Combi

Post by berbers » Tue Jun 19, 2018 5:50 pm

Turbomax isos are generally ok. However, If they do leak, the only option is to replace them.

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