Some radiators not heating up and hot expansion tank Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Cyclefleet]

Some radiators not heating up, and water in expansion tank is hot
Just replaced pump, drained and refilled system. Any ideas?

[plumbbob]

Airlock an a badly designed system.

https://www.diydoctor.org.uk/forums/view ... hp?t=15333

[Cyclefleet]

Thanks plumbob - apart from the risk of F/E tank rupture, will this condition present any other problems?

All radiators have been bled - anything else you suggest to clear air lock?

[plumbbob]

Shut off any hot radiators, and turn the pump on and off several times. Ensure the speed is set to three. This may force the airlock into the rads. IF this doesn't work you need to open up a coupling and allow a larger quantity of water to escape bringing the air with it.

Water circulating through the header tank introduces oxygen into the closed system. This will eventually cause corrosion to the rads and the resulting sludge can block both rads and pipework.