Last month we had to replace the horstmann valve as we had no hot water. This week we have no heating sometimes and the other horstmann CH valve seems to be the problem. We have override the valve and the system will start. We replaced this CH value about 2 years ago.
We are getting the timing switch saying it is on, on the control panel but the boiler is not connecting for the CH. It has been working ok for the HW.
Could there be sludge in the system that is causing this too happen? or any other thoughts please