Releasing excess system pressure through the PRV

grill · 8 Sep 2007

Alright guys,

If a customer has overfilled their system and you need to drop it back down to 1 bar is it bad practice to do this using the PRV.

I was checking through a manual of a Chaff et Maury and this is how it tells you to drain down the boiler. However from chatting to other people the say that this is bad practice as you can get crap stuck in the valve and it will leak forever.

Just wanted your thoughts on this really.

Grill

Bahco · 8 Sep 2007

Drain excess pressure via a drain plug under your radiator and not the PRV.

bripl · 8 Sep 2007

use the prv at you peril,esp on a french boiler

the chaff has a drain point under the pump i believe[not the flats on the lisburn road]

Bahco · 8 Sep 2007

Bahco said:
Drain excess pressure via a drain plug under your radiator and not the PRV.

Drain off valve not plug.

weareleeds · 8 Sep 2007

If you do release pressure from prv you will invariably have to clean seating or change it which is why a lot of makers are now putting the prv away & out of sight to remove temptation

oilman · 8 Sep 2007

weareleeds said:
If you do release pressure from prv you will invariably have to clean seating or change it ..............

What nonsense. The PRV is supposed to be checked to ensure it operates at service time. There's a BS Spec. If you don't open it, how do you know it isn't stuck. There is also a BS spec for the cleanliness of the system water. If there's crud in it, and it gets on the valve seat, it isn't clean. I open lots of thesethings, I have to replace very few, so "invariably" is in appropriate.

grill · 8 Sep 2007

The only reason i ask is that the last job i was at i released some pressure through the PRV and then it just kept running. I opened it up full and closed it again. Must have flushed any crap out of it.

Im a bit wary of them to be honest. It doesnt mention in the mnauals anything about opening the PRV during a normal service. Wasnt away of any spec either.

Grill

Agile · 8 Sep 2007

Boiler manuals are designed for competent boiler engineers, not DIYers or electricians. Furthermore boiler manufacturers assume a totally clean system but even so almost all say do NOT drain from the PRV.

Its certainly good practice to check the PRV on a service but in many cases that will mean that it will have to be replaced as well so most engineers excercise some judgement at that point.

Reminds me of trainer on an unvented course who said the T&P valve should be tested at a service. Then he said that if the lift the valve it will almost certainly leak and have to be replaced and if you overheat the cylinder to 95 C then you are risking a very serious problem.

Tony

gas4you · 8 Sep 2007

All safety devices have to be checked for operation during a boiler service I thought.

diynot

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

Releasing excess system pressure through the PRV

Similar threads