why would water still be coming from boiler sensing pipe?

[giveitawhirl]

hi, i'm trying to replace diverter valve membranes on a baxi 105he. i have isolated cold water and run/left on downstairs hot water tap until empty and drained the boiler. the problem is when disconnecting the sensing pipe from the dhw diverter. water just keeps coming from the sensing pipe. can anyone tell me why this is and what to do about it. thanks.

 

[cjg]

from expansion vessel? shut flow/return, shut cold, open taps , lose pump have cloth ready.
take it from there,

 

[king of pipes]

Valves on the boiler may not be holding back the system water ?? If the expansion vessel has failed it could be full of water press in the Schrader valve to see if there is air in there ?? If water comes out chances are it's shot

 

[ShaunCorbs]

You need to drain the heating system / the boiler heating side

 

[giveitawhirl]

thanks guys, sorted. expansion vessel seems sounds right. it did stop eventually. waiting for ch diaphragm to do that now. the valve cover seems to be welded together by limescale(?) so guess it'll just be a case of pull it off with pliers or something.