Replacing Pressure Relief Valve

[PlumberNot]

Hello all - First post on this forum - hope someone can advise please....

I am pretty sure the pressure relief valve needs replacing on my combi boiler and wondered if anyone has replaced one on a BG C1 aka Worcester Bosch 28si II.

I remember the pressure nearing 3 bar at one point on the combi and next thing I knew the pressure was down to 0 bar - the pressure relief valve must had kicked in and sure enough water was coming out the discharge pipe outside.

A little research has enlightened me that when the PRV releases water, it is likely to need replacing as the valve may have dirt inside making it unable to close. Sure enough - after repressurising system to a stable 1 bar - water is still being released outside.

I phoned worcester bosch technical who also believed the PRV needs replacing. The techie on the phone stated that it would be quite an easy job even for an amateur. Advice was to release water through a radiator (3 buckets full) turn boiler off and unscrew a couple of nuts connecting the PRV and replace. He said it was ok to be do this myself as I would not be tempering with the gas.

A few quotes from plumbers in my area averaged around £100 - £150. I am very tempted to have a go myself buying the part from Plumbcenter or similar.

Therefore I would like to know if anyone on this forum has replaced the PRV on their Worcester bosch or indeed any other combi as I would imagine the process would be the same.

If successful - we could turn this into a sticky.

Many thanks and (sorry for the long post!!)

 

[kevplumb]

I remember the pressure nearing 3 bar at one point on the combi and next thing I knew the pressure was down to 0 bar - the pressure relief valve must had kicked in and sure enough water was coming out the discharge pipe outside.

find out why first or the new one will go the same way

my money is on ex vessel needs recharging

see the FAQ post

 

[PlumberNot]

Thanks for the reply kevplumb

Do you think I have to render the services of a plumber?

I have read the FAQ regarding repressurising the expansion vessel - is it something I can do or shall I call a plumber?

Shall I still look to changing the PRV?

Many Thanks

 

[stephen101264]

Hi plumbernot,
If the boiler is over 10 years old the rubber seal in the PRV could be perished. Disconnect the boiler from the mains electricity FIRST and take the front cover off. Have a look where the overflow pipe reaches the boiler and you will see the valve. it should be connected by compression fittings. If you decide to renew you will need two water pump pliers, one to hold the valve and one to undo the nuts. Perhaps also a junior hacksaw to cut off the old olives. Obviously you will also need to drain the system of water first. Plumbcentre may not have the part, you may need a dedicated boiler spares supply company.

I changed one in my potterton and I am not a qualified plumber.
If your pressure is rising you must have other problems as well but it would not do any harm to change it, but you may find it is tucked away at the back of the boiler in an awkward place to get to. good luck with the job.

 

[EliteHeat]

My money's on Kev's idea!

 

[corgiman]

mine too

but I like stephens advice lmao

 

[clf-gas]

mine too

but I like stephens advice lmao

With kev all the way

Would'nt use pump pliers though, would just remove the retaining clip

 

[corgiman]

mine too

but I like stephens advice lmao

With kev all the way

Would'nt use pump pliers though, would just remove the retaining clip

NAH

get your self a pair of 18" stilsons, large hacksaw, and a sledge before you even think about working on a combi

lmao

 

[clf-gas]

 

[PlumberNot]

Thanks for all your replies

I have taken the cover off the combi and identified where the PRV is. Lukily it's at the front of the boilder and looks accessible

Attached is a pic of the valve. *just realised I can't insert an image - what's the best way to insert an image?

I think I will buy the part first and then it will help me identified where I need to undo the bolts.

Any additional advice welcome

Ta
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[scatmanjohn]

You are not listening to the advice that has been given.

Check the expansion vessel first

 

[corgiman]

You are not listening to the advice that has been given.

Check the expansion vessel first

here here

check the expansion vessel

 

[clf-gas]

Plumbernot, if this link works then scroll down and have a read //www.diynot.com/forums/viewtopic.php?t=37170

If you check and ok then e-mail me and I will send you a copy of the instuctions

 

[ChrisR]

I don't see much point bothering with drain-offs on rads - you might as well drain through the prv if you're going to replace it!

 

[PlumberNot]

Oh sorry...

I have read the faq re: repressurising expansion vessel

Some questions if you don't mind answering:

1. where can I find the pressure fill valve? Pic of boiler added



2. It seems that my combi may have a "mini-expansion vessel" would this be the thing I am looking for?



3. If I find the pressure vessel valve and press the central pin - where will water come out if there is any?

4. How do I drain water from drain cock? where is it? Can I bleed water from the radiator?

5. Is it sufficient to turn boiler to 'off' position and switch off at the mains?

Once I have found where all these bits are then I may give it a go (along with some confidence)

Thanks