A couple of months ago I fitted a thermostatic mixer for a friend to provide warm water to an outside tap for dog showering purposes. I was a little uneasy about it working well with a gravity HW system and mains cold but the manufacturer assured me that it would work.
Indeed, it did work fine until recently when it started to exhibit weird behaviour. Now when you turn on the tap, nothing comes out. No water at all, neither hot, cold or warm. If you leave the tap open for a few minutes, the water starts flowing and it seems to work fine. I tried tapping on the valve to see if maybe this would free a stuck non-return valve but it had no effect.
This is repeated on a daily basis. Can anyone explain this behaviour?
Tim