Hi, I was hoping someone had seen this issue before and might be able to help.
My boiler works fine when the heating is on but as soon as the heating is turned off the pressure begins to fall as shown in the youtube video link I've attached below. In cold weather this is exacerbated and the pressure drops to zero within minutes. When the teparature is warmer though it doesn't fall as fast. In the summer it takes weeks to fall like shown in the video so it is completely external temparature dependant. This makes me think it's not a leak because surely that would be a consistent drop in pressure?
Any help would be greatly appreciated!
https://youtu.be/_ipl8-Rf1Pg