cold radiator – air lock?

[Anonymous]

A year ago, I redecorated my bathroom which involved taking the raiator off. This rad previously worked satisfactorily, and did so again after the job.

Then a few weeks ago, I did some other work on the CH system which involved draining it down. Refilling this rad has always been very slow. Having done so, though, it now stubbonly remains cold

I believe this rad and one other are on the hot water circuit.

There is a pump and a 3 way valve, and some pipework above the boiler whose function I don’t understand (eg one 22mm pipe contolled by a wheel valve comes off between the pump flow side and the 3 way valve – this has been more or less completely closed hiterto, but it seems to make no difference to anything whether it’s opened or closed)

The rad is full of water. I took it off last night and cleaned it out. There was gunge in it, but not an inordinate amount.

Without the rad on, the return side of the pipework produced a reasonable flow when I turned the control valve on, but the flow side only produced a tiny trickle, virtually nothing.

I took off the thermostatic control valve on the flow side and virtually no water came out (but I could see water in the pipe)

I replaced the thermostatic valve and the rad and tried to force water through the rad by shutting of the other rad on the hot water circuit, increading the pump head to max and shutting off the heating circuit with no success.

Otherwise the whole system works normally and satisfactorily, ie pleanty of heat in the house and plenty of hot water.

Do I have an air lock in the flow pipework supplying this rad? Or is my three way valve not working properly?

Could I clear an air lock by momentarily connecting a hose and the cold water mains to the flow side of the pipework? Could this do any harm?

Could anyone suggest any other diagnostic procedures?

PS my regular heating contractor does not seem to be interested in coming to sort out this problem for me.

Thanks in advance for any help

[peter_harris_1999Participant]

Readers might like to know that I connected my main cold water supply to the flow side pipework feeding this rad, opened the rad valve and turned the water on.

This shifted a blockage made up of rust particles and other debris, which I then draied from the valve into a recepticle.

Problem solved. I clearly need to drain down and flush out the whole system sometiome soon using a similar technique.

[Author]

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