Logic 24 combi boiler problem

[C5VHB]

Hi,
I have a Logic 24 Combi boiler. I have started having issues with the heating a couple of days ago when I realised the CH was not heating the radiators as much as it used to. I thought this may have been down to the pressure and tried to increase it slightly because it was on 1 bar and im aware it should be between 1.5 and 2. However, i think i turned the wrong valve. When i turned this valve it sounded like water running/escaping. Now...the radiators down stairs dont heat up at all and the boiler shows "pump overrun". The upstairs radiators are slightly warm at the bottom. I have no idea what I have done but i know it must have something to do with the valve i opened! Please help. Thank you.

 

[terryplumb]

Picture of the valve you opened may assist .when you opened it did pressure increase ?

 

[C5VHB]

Thanks for the quick reply. After finding the manual online i have realised It was the valve that helps to top up the pressure. Now that I have done that the radiators are heating up. My next problem now is i cant work out weather or not the valve beside the pressure gauge should be open or closed all the time?? Also when the heating is on the pressure now goes about 2 slightly. Does this mean i should bleed a radiator to release the pressure slightly? I will post the picture of the valve beside the pressure gauge now.

 

[C5VHB]

 

[C5VHB]

This was while the heating is turned off and no hot water running...should this valve be closed or open at all times? Thanks

 

[terryplumb]

That valve is not used to top up ,it is not the filling loop. It is an isolation valve on the central heating flow pipe. It should be open in normal use ,if its closed you will not get hot water from the boiler to radiators.

 

[C5VHB]

Brilliant thank you. With the pressure currently on 2 bar while the heating is on, is this safe?

 

[terryplumb]

For your info, boiler pressure should be just over 1 bar WHEN COLD. When c/heating is on and boiler heating water the water expands and pressure increases, up to around 2 bar.when off and cold ,it reduces back.all quite normal.if it goes up to around 3 bar the pressure relief valve will open and allow water to run out the system ( usually to a pipe outside ) to reduce pressure .

 

[C5VHB]

Okay thank you. Thanks for the quick reply and help.

 

[terryplumb]

Your welcome. Your filling loop ,should you need to ever top up pressure in future ,is on the right hand side .where the vertical pipes join the boiler. You will see a short pipe ,horizontal, with a lever at each end.when they are both opened it allows mains cold water to enter the central heating system and tops pressure up. You then close both when 1 bar is reached on the gauge.