how to remove a Potterton PRV

[otherparty]

Hi guys
I have a Performa 24 combi. I need to replace the PRV as it is leaking thru the external discharge pipe. I've bought the new part, but i'm not really sure what to unscrew in order to remove the old one. I've attached pics, one of the new part and one of the old. In the current assembly, it looks like there are two 'screws' underneath the PRV - one small to the PRV and a bigger one to the pipe below. Which one should i unscrew? Or should i unscrew both? If so, in which order? Probably silly questions, but i don't want to mess this up lol.

Thanks for any advice.

View media item 40690 View media item 40691

 

[bobw1956]

If you can,t work that out, best left for a pro

 

[otherparty]

If you can,t work that out, best left for a pro

Thanks for that very helpful response.

 

[misterdubya]

undo the grub screw that is in the centre of your pic and undo the nut on the discharge pipe.

 

[gas112]

Empty boiler first though

 

[otherparty]

ok, so i've emptied boiler, removed nut (figured grub screw will be easier to remove once i've got the PRV out). Am i right in thinking i need to unscrew a (tiny) allen key bolt, before i can pull out the PRV? If so it's bloody difficult to get to!

Thanks again

 

[misterdubya]

That IS the grubscrew and you will have to loosen or take it right out or the prv wont budge. It holds it in position. Easy enough to get it there with a small allen key. If its corroded in, you'll have to drill it out - thats when the fun begins.

 

[otherparty]

That IS the grubscrew and you will have to loosen or take it right out or the prv wont budge. It holds it in position. Easy enough to get it there with a small allen key. If its corroded in, you'll have to drill it out - thats when the fun begins.

ok, thanks. the PRV is completely out So now i just have to remove the nut under the PRV (in order to reuse it with the new PRV)...
I'm getting there

 

[otherparty]

all done, and doesn't look to be leaking (touch wood)
thanks guys

 

[The831Bunny]

Did you check and repressurise the expansion vessel while it was drained? That will be the cause of the PRV leaking in the first place.

 

[Agile]

Was it as simple as it looked?

Tony

 

[otherparty]

Did you check and repressurise the expansion vessel while it was drained? That will be the cause of the PRV leaking in the first place.

No. The whole problem started after i had it serviced. Previously pressure had always been on the high side, i.e. over 3 bar! The guy tested everything (inc. expansion vessel) and concluded all was ok, but, after manually operating the PRV, it didn't re-seat properly and he suggested i change it.

 

[The831Bunny]

Fair enough

 

[BARNY78BG]

hi, just wondering if there was a reason the pressure was over 3 bar? did you over pressurise? cos normally if pressure is over 3bar then the prv would activate and press should drop down, so my querie revloves around what is causing your pressure to stay over 3bar? sounds like something passing into heating to keep press up!

 

[otherparty]

hi, just wondering if there was a reason the pressure was over 3 bar? did you over pressurise? cos normally if pressure is over 3bar then the prv would activate and press should drop down, so my querie revloves around what is causing your pressure to stay over 3bar? sounds like something passing into heating to keep press up!

Yeh, that is a good question. I did possibly overpressurise about a yr ago (when i had no clue about this stuff and perhaps overfilled). The guy who did the servicing couldn't seem to find any problem. I think he suspected the expansion vessel, but, as i said, testing concluded it was ok. My assumption therefore is that only the PRV was faulty, as, firstly, it did not activate at 3 bar and, secondly, it leaked after manual operation. Does that sound plausible?