Expansion vessel

[Ian_P]

I have noticed that the pressure rises considerably during the heating cycle of my boiler, getting close to 3 bar. One of the effects of this appears to be that the diaphragm valve doesn’t function on the combi boiler meaning we don’t get hot water running to our shower whilst the heating is on. The pressure appears to drop away after the heating has been on to very little.

From reading stuff on this site it seems to be that this is likely to be a problem with the expansion vessel. Is there anything else that this could be?

I also understand that only a Corgi registered plumber can deal with this, is this right? And finally, how much is it likely to cost to get it recalibrated?

Thanks

Ian

 

[gasmick2]

Hi you do not mention what make the boiler is but it does sound like you have 2 problems 1 is the diverter valve dipahram as its that part that cuts off the port to the heating on water only, so it will need replacing.
2 The expansion vessel is the other prob but on saying that it may just need recharging up to 0.7 bar or there abouts according to your M I
it could be punctured if so it needs replacing or an external one fitted of the same size in litres or it could be the shreider valve just leaking and needs replacing and then recharging so it looks like you will need someone to do it for you