DIY Doctor

Possible airlock in system?

Postby Bron » Fri Jan 21, 2011 4:22 pm

Any advice please.

We drained our system to fit a new towel radiator and took off another radiator to decorate at the same time. We live in a small flat and only have 3 radiators in total however we have an old baxi back boiler and water cylinder. The tank is fed by a smaller feed and expansion tank which lives above it in our airing cupboard.
We drained off the system seemingly successfully however we did not turn the motor valve to manual it stayed on auto when we did and since refilling, the radiators are all full of water, including the new one and have all been bled but when we put the heating on, the boiler fires up and the pump is on but vibrating and making a lot more noise than normal and the radiators are not getting warm/hot.
The pump is making such a noise I have turned it all off at a fuse switch near the boiler (chimney breast) as I.m worried it may become damaged?????
Everything we have read suggests we have an airlock. We have read to try and bleed the pump by turning the large screw in the centre but this really won't budge.........also having looked for more possible valves to bleed the system from the pump to the cylinder I am unsure and don't really know what I'm looking for.
Should we drain/refill the system again with the motor in manual now?
Did we put the heating on too soon after refilling? Should we have added inhibitor?

Thanks in advance! :dunno:
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Simply Build It

Postby htg engineer » Sat Jan 22, 2011 7:41 pm

You need to vent the pump - undo the screw in the centre (turn anti-clockwise) once the air has cleared from the pump - it'll probably work as before - if the screw is chewed and wont budge you may need to change the pump.

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