Hi group and Seasons Greetings to all :-)
I think I need to replace the expansion vessel in my six year old Ariston EuroCombi SX20, but just want to check if I have overlooked something first before I try and get one before Christmas and end up paying what I expect to be a hefty price for a part I may not need.
The short version of the story so far.
Started a week or so ago with the boiler cutting out and the system pressure fluctuating from 2 - 3 bar.
So got a CH fitter out to have a look as I did not have the time and was not sure what to do et etc. He service the boiler, cleaned it out etc and told me that he believed the expansion vessel had just lost its pressure. He told me no water came out of the valve. He refilled the boiler and set the expansion vessel air side to 1bar. He also said he thought the pressure relief valve may be faulty. That night when I checked the overflow there was a dribble from it. Before he touched the boiler there was no evidence of water coming from the overflow. On Friday I fitted a new prv and the result is still the same.
Now tonight the system pressure was running at about only 1.5 - 3 bar, so I checked the pressure of the air side of the expansion vessel and nothing. So I pressurised the air side to 1 bar as stated in the service manual, refilled the boiler and fired it up. The pressure got up to 3 bar and the prv is dumping a small amount of water.
So my question here is have I overlooked something else (i.e. another pressure regulator of something else) or has the diaphragm one the expansion vessel damaged and thus needs replaced.
According to the service manual the exp, vessel can be changed without removing the boiler if there is enough headroom which I have, so changing the exp vessel should not be too difficult, but don't want to spend the cash if it may be something else.
Anyway if anyone can shed any new light on this I would be grateful as I need to get a new exp vessel by Tuesday for the holiday season.
Alternatively will I do any more damage if I just keep topping the system up until after the holidays?
Cheers
Duncan