I have a Potterton Promax Combi HE Plus boiler.
Yesterday I tried to repressurise the system to prepare for winter. We have a refilling loop under the sink that I have to open and the water from the cold main will flow into the central heating system.
After I did that and the pressure gauge looked fine (~1.5 bar), I tried to switch on the heating by changing the thermostat to 25°C. The boiler indeed switched on, but the radiators were all cold - everywhere.
Then I noticed that the "Heating Return" valve was in closed position on the bottom of my boiler - see picture attached.
I assumed it was wrong, so I opened it and the radiators started to heating up immediately.
It was all fine and I was happy - until this morning, when I noticed that the pressure dropped to zero and error E119 was displayed on my boiler.
Can you please help me what should be the position of the "Heating Return"?
Also could this long unused (unheated) period cause that I should play with the pressue a bit before it settles?