How to drain expasion tank

[lambretta]

Hi
Can someone help me on how to drain a Ideal Respnse 120 combi boiler
my pressure drops after a while after top up.When the central heating is on,the gauge goes up to about 3 bar then once everthing is off it sits below 1 bar.
There are no leaks in the radaitor flow or return pipes.I have checked the expansion tank and when you put heating on the tank is hot at top and bottom.I also noticed some time ago that when you were running hot water on it's own,the radaitor that just has constant flow with no control was hot.

Thanks Gman1966

 

[JPC]

seems ev has gone and other problems poss, so you might need to get someone out to have a look

are you draining down to solve your problem ?