How to change PRV on Glow worm ultracom 30 cxi combi boiler

[kingpayne]

Hi,

I have a Glow worm ultracom 30 cxi combi boiler with a suspected faulty PRV. I am looking for advice on how to change it and best way to drain down the boiler.

Just a bit of background information for you:
I had problems with my heating last year with low pressure and recharged the expansion vessel which solved the problem. Now again i have low pressure issues. I have checked the expansion vessel which was nearly empty and recharged. The heating works now but when the boiler is not running it starts to loose pressure, so in the morning the heating does not come on due to low pressure. The PRV has been leaking and operated at the weekend as when i was in the kitchen water was pouring from the outlet.

Many thanks for your help

 

[ScottACL]

I always manually lift the faulty PRV and drain, it won't seal again but not a problem if replacing. Note, make sure expansion vessel is not faulty has this with lift PRV!

 

[captain_pugwash]

First you need to switch the boiler off, then turn off the water supply and return - generally the quarter turn valves in the pipes that go into the boiler. At this point you can drain down the boiler - as you are replacing the PRV you can press the lever (if it has one) to discharge the water out of the boiler. If it doesn't have a lever on then there will be a drain valve - put a small piece of hose over the outlet and feed in to bowl or bucket. Once empty there is generally a metal tab that you need to pull out that will then allow you to pull out the PRV - they are generally push fit. If you order a new PRV you will see how it fits into the housing.

I have a Glow Worm 30 Si and have replaced the PRV a couple of times - generally if there is an airlock the PRV operates to release the pressure and then never really seems to properly seal again - tends to dribble away pressure. I put a jam jar under my PRV outlet pipe to see how fast water was coming out to make sure that this was indeed the reason for the pressure loss (I have also had a pressure loss due to a small leak in an elbow joint under the floor boards so it's not always a PRV).

Good luck!

 

[captain_pugwash]

Here you - the manual shows how to drain down and replace the PRV

http://www.glow-worm.co.uk/stepone/data/downloads_sd/51/00/00/cxi-range.pdf

 

[kingpayne]

Thanks for all your help.

Got a new PRV last night and fitted it. The old one was rather dirty with some sludge in. Pressure was still at 1.0 bar this morning and heating was working. Woohoo.. That will keep the Mrs quiet.

Cheers