PRV advice sought

[Stonegnome]

Hi Guys,

I have a Vaillant VCW GB 242 E which has probably been installed for over 15 years. It all works fine but whoever installed it never bothered to plumb in the PRV outlet which is just set to discharge nicely (as in "not nicely at all") down the wall should it ever fire! Naturally I'd like to rectify this but opinion appears to be divided as to whether this PRV should be hard plumbed in continuous pipe, or whether it should be allowed to discharge into a catch-pot arrangement. Does anyone have any advice to impart, please? Also, it's pretty awkward to get at to take a good look at it with the current kitchen furniture arrangement (it's all coming out soon...) Does anyone know what kind of connection it takes? The most I can tell is that it has an internal screw thread but I can't tell what size or guauge.

Any help gratefully received.

-S

 

[gigz]

It should be 15mm copper taken to outside and positioned where it can be seen but where it wont do any harm to anyone if it blows off, i normally kick it back to the wall

 

[oilman]

It's most likely a 1/2 bsp fitting. It might be possible to extend from the existing pipe. Many pipes are put straight through an external wall, but if you have the boiler where no external wall is available a tundish is usually fitted. Having said that, what is needed is a pipe from the boiler that CANNOT be blocked, and the longer it gets, the more likely blockages can occur. A tundish allows free drainage, provided the pipe isn't blocked, while giving a short run from the boiler. But I bet there'll be other opinions.

 

[kevplumb]

Does anyone know what kind of connection it takes? The most I can tell is that it has an internal screw thread but I can't tell what size or guauge.

Any help gratefully received.

3/4"" bsp male iron x 15mm comp

 

[oilman]

Are you thinking of the boiler kev? I was thinking of the already fitted PRV.

 

[kevplumb]

yup 3/4"" female on the prv (just had a look ) in the mi's

 

[oilman]

OK.

 

[Stonegnome]

Thanks for all this, guys. The boiler is on an outside wall, so there's no problem taking the pipework straight down and then out.

I can believe the 3/4" fitting -- I tried a couple of straight-through compression fittings that I had to hand just to get a rough idea of its size and the 22mm one would seem to be just a bit too big.

(Incidentally -- and I pass this on to amuse (as in horrify?) you-- there has been an advantange to this PRV not being plumbed in the past. The last time a service engineer came to repair a minor fault he cursed that he couldn't use the PRV to drain down!!)

-S

 

[oilman]

That's not an advantage though. The PRV should be operated at the time the boiler is serviced to check that it isn't stuck, so using it to drain the pressure checks it at the same time. If it can't reseat, it needs replacing.

 

[Stonegnome]

OK; point taken. I promise not to shout at him next time he comes and finds he no longer has to entertain us by juggling lots of rubber tubing and buckets!