I recently drained the whole system and the boiler only comes on for about a minute, overheat and cuts out. I have down drained the system 4 times and cannot shift the airlock. The pumps new, the rad's are fine. Can I do a pressure flush to remove the airlock? I cannot find any form of valve on the system except upon removal of the front lower cover whereby there is a hose take-off point that just drips out 'muddy water'. Next to it (left) is an angled pipe with a standard screw head but also a hexagonal nut. If I undo this, does it bleed the boiler? As yet, I have not removed the nut because I am nor familier with what it's for. Any help would be thankfully received. The boiler was working quite well before I drained it although the rads, especially up stairs never got really hot, hence the drain. Thankyou.

Chris., March 2010

Thanks guys. I have tried running the pump with the silver disc off and it made no difference. On draining the whole system each time, the pump ran as sweet as a nut. When I bled the to 'legs' next to the silver flow valve in the middle, (the one with the little flat lever) the pump went noisy again, like a slosh-slosh noise. so the air was back in the system. I am not familier with the location of this thermostat phile. All I can see is the small 'L' shaped tube with the screw head and nut all in one. Thankyou.

Chris

Chris, March 2010

Thanks guys. I have tried running the pump with the silver disc off and it made no difference. On draining the whole system each time, the pump ran as sweet as a nut. When I bled the to 'legs' next to the silver flow valve in the middle, (the one with the little flat lever) the pump went noisy again, like a slosh-slosh noise. so the air was back in the system. I am not familier with the location of this thermostat phile. All I can see is the small 'L' shaped tube with the screw head and nut all in one. Thankyou.

Chris, March 2010

try venting the pump with the system running and with the system off, if its a grundfoss pump or similar there is a silver screw in the centre which can be loostened with a flat blade screw driver, this quite often can stop the system working if there is air in the pump

john, March 2010

take the thermstate phile out of the boiler, turn it on and let it boile for 10/15 sec turn off and see what happens if nothing repeat.

erj, March 2010