Potterton Lynx2 Combi

Joined
10 May 2006
Messages
505
Reaction score
0
Country
United Kingdom
hello guys hope you can help. The PRV of the above boiler is leaking. When the heating is on the pressure gauge shows below 3 bars and after 4-5 hours the pressure drops completely and the boiler does not fire up. Does the valve have a compression fitting on both sides? Does anyone know it’s part number? I have looked in the manual and the only mention is PRV 3bar ( c/w washer). I don’t know what c/w washer means and besides there is no part number. Thank you in advance for your time and help.
 
Sponsored Links
when you say below 3 Bar what do you mean ? is it near 3 bar or what pressure is it at ?
 
Sponsored Links
when you say below 3 Bar what do you mean ? is it near 3 bar or what pressure is it at ?
Hi ianmcd. I would say 2.7 bar so I guess the PRV should not open. But it does leak very slowly and after a while the pressure drops to zero.
 
yes that is how it operates, you have an expansion problem you need the EV re-charged or possibly replaced and probably a new PRV now too, no point in replacing the PRV until your expansion prolem is sorted
 
yes that is how it operates, you have an expansion problem you need the EV re-charged or possibly replaced and probably a new PRV now too, no point in replacing the PRV until your expansion prolem is sorted
Hi ianmcd. If I had an EV problem don’t you think the pressure would go over 3 bars when CH on as the primary water would have nowhere to expand? My boiler pressure has never gone beyond 3bars so far. That’s why I think it is only the PRV which lets by. Having said that, there is no harm in checking the EV pressure as well I suppose. Do you know if the PRV has compression nuts on both sides? Is it straight forward to replace it or tricky? Thanks for your time.
 
You'll need to get a Gas-Safe heating eng. in to sort this out.
The expansion vessel is behind the boiler and the valve is only accessible after extensive removal of parts within the combustion chamber. In my experience they are never checked on this model due to the extra labour.
The PRV is not particularly easy to remove either being stuck behind the pump.

This is a 25+ year old boiler...don't waste your time on it...most sound like a kettle and were scrap a decade ago.
Don't be surprised if the pcb plays up when it's hinged out...the solder joints fail for fun and will need repair.
 
Hi ianmcd. If I had an EV problem don’t you think the pressure would go over 3 bars when CH on as the primary water would have nowhere to expand? My boiler pressure has never gone beyond 3bars so far. That’s why I think it is only the PRV which lets by. Having said that, there is no harm in checking the EV pressure as well I suppose. Do you know if the PRV has compression nuts on both sides? Is it straight forward to replace it or tricky? Thanks for your time.
The PRV is not a calibrated electronic instrument, it is simply a spring seated valve and many will open at 2.7 Bar you have an expansion problem and a very old and rubbish boiler, they were scrap when they were new. it cant go above 3 Bar as that is why the PRV is there it is designed to open at 3Bar to protect the boiler
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top