Combi boiler expansion vessel.

[frank rabbets]

I have Worcester 30 CDi boiler and the diaphragm in the EV has failed. I have pumped it full of air and the pressure of the system is now stable. Question is will any harm be done? The water is now in contact with air. That's the only difference I can think of. The older type systems had a header tank for the rads so air was in contact with the water in that situation. "Change the EV" I hear you say. Nobody wants to know. Looks like the boiler needs taking to bits to get it out.

 

[StarCruiser]

One option is to add an external EV and blank off the connection to the internal EV.

 

[Rob Cowell]

I have Worcester 30 CDi boiler and the diaphragm in the EV has failed. I have pumped it full of air and the pressure of the system is now stable. Question is will any harm be done? The water is now in contact with air. That's the only difference I can think of. The older type systems had a header tank for the rads so air was in contact with the water in that situation. "Change the EV" I hear you say. Nobody wants to know. Looks like the boiler needs taking to bits to get it out.

I am not a plumber. Although I have replaced an EV in my Worcester combi - fortunately didn't need anything else taking off to get it out.

If the diaphragm has gone I take it water was coming out of the air valve when you pressed it? So if you now pump air in there you have pressurised the whole system. If the water warms up and wants to expand it can't because there is no working EV. Hopefully your pressure relief valve will work and allow water out of the system to compensate. But you will continually be losing water and pressure when the heating is on until you replace the EV.

 

[Andy]

Some Worcester boilers require the boiler taking off the wall. To change the ev, right pain in the arse...... but that’s Worcesters.
Fit external vessel

 

[frank rabbets]

The expansion vessel is now half full of air under pressure as it would be if the diaphragm was whole and the system keeps a constant pressure whether hot or cold. Not worried about whether the system works or not, it does, but the question is "will any harm be done?". Cant get to the EV to block it off otherwise I would have already fitted a remote EV.

 

[StarCruiser]

The problem may come that you get air out of the EV into the water. That air may get bled out of a rad or auto air vent. You may be lucky.
Also the water will be in contact with the steel of the EV not the bladder but that might not corrode for a long while.

Did you actually get water out the schrader valve?

 

[frank rabbets]

I did not get water out of the schrader valve. I depressurised the system and connected a pump to the scrader valve. I gave it a few pumps to see if I could pressurise the EV but I could not get pressure. After a few more pumps I heard bubbles going into the ch system so assumed that the EV was full of air as it's bottom fed with water. I pressureised the system to 1.6 bar, bled the rads ( no air came out), and fired up the ch. Boiler needed a little fill to get it back to 1.6 but all is now well and gauge stable hot or cold. Just worried about corrosion but I do add a bottle of ( very expensive0 inhibitor every 3 years. Thanks for feedback

 

[silvercruiser]

Sounds like the expansion vessel is ok to me. you have managed to re pressurise the vessel and push some water back into the system. if the pressure gauge is staying in range and continues too, over the next week you should be ok. What pressure did you pump the vessel too?