Glow Worm PRV & Expansion Vessel Help

[Daisypop]

Having read other topics on this subject we are fairly sure that our PRV needs replacing. However will we also need to replace the expansion vessel or could it just be the PRV?

If we need to replace the expansion vessel, do we need to buy a Glow Worm one or not? Also, can you add the new one to the heating return, and if so will the system work with the faulty one still in place?

I would appreciate any help I can get on this one.

Thanks!

 

[linkyplumb]

Which Glowworm is it?

 

[Blooflame]

Having read other topics on this subject we are fairly sure that our PRV needs replacing. However will we also need to replace the expansion vessel or could it just be the PRV?

If we need to replace the expansion vessel, do we need to buy a Glow Worm one or not? Also, can you add the new one to the heating return, and if so will the system work with the faulty one still in place?

I would appreciate any help I can get on this one.

Thanks!

You hven't said what the problem is

 

[Daisypop]

Sorry I didn't get an email to tell me anyone had replied, so I've just seen this at work.

Can't give model at the moment as I can't check it, but the problem was the pressure going down to zero constantly.

We have now put in a new PRV and it seems to be working much better although there is still a very tiny drop in pressure but nowhere near as bad. We have also checked everywhere for leaks of which there are none.

Now we still have a problem with the hot water cutting out after 30 seconds, the red light comes on and the water runs cold. You can get it boiling for a very short time but that's it. Any suggestions what we need to do to fix this?

 

[Blooflame]

Right Daisypop, the problem is more than likely in the expansion vessl. It has a membrane, half fills with water from the system the other half should be full of air to absorb expansion in the CH system as it gets hot. if you undo the schrader valve cap on the vessel (like a bicycle valve) and press, like when you would let a tyre down, air should come out, if it's water then the membrane is split and a new expansion vessel needed. Alternatively, and more likely, u need to pump air into the expansion vessel using a foot pump. The PRV needs to be kept open and between 0.75 - 1.0 bar needed. Let me know Daisypop