Worcester 24CDi. Faulty expansion vessel or am I missing som

[Pjsouthsea]

I have a Worcester 24CDi boiler that has worked with no problems what so ever until now. I woke up this morning to a freezing flat and found that there was no water in the system and the heating light flashing.

I checked to see if the pressure valve had released water outside and there was nothing. I have checked all the pipe work I can find and there
are no leaks. I filled the system again, it held the pressure until i turned the heating on after which the pressure dropped fairly quickly and the system needed to be refilled again. In addition to this, steam seemed to be coming from the automatic air vent on the top of the boiler.

Would this be caused by a faulty expansion vessel or am I missing something that I should be looking for?

Any advice would be greatly appreciated.

Thanks

 

[Aquaheat]

Could be poor circulation. Have you checked the pump is running?

 

[Dan Robinson]

Or the expansion vessel is goosed - drain the system and check the vessel is holding a charge.

 

[Aquaheat]

It could be...

OP doesnt say that the pressure rises past 3 bar and if there is any water from the PRV after the pressure drop.

more info could lead us to the correct conclusion?

Steam from the AAV says to me that its overheating and not a pressure problem.