Airlock on part of central heating system after drain down - One pipe system

[JackK]

I drained down my one pipe system for boiler test and when refilled the central heating is only partly working - I can see one horizontal pipe that feeds the radiators that feels cold and I am sure it is an airlock.

Is it advisable to drain down and refill with the hope this might clear the blockage?

There is water in the FandE tank for sure

I have tried to bleed the radiators and the ones that are cold have no water in them

 

[terryplumb]

Did you clean out the f&e tank before draining down ?
Which radiators are not full of water ,are they on a higher floor level than rads that did fill ?

 

[JackK]

The fande tank is fairly new and not dirty

The radiators affected are the old cast iron radiators - They have bib pipework as well

I am quite sure there is an airlock and I wonder how it can be removed

Raditor on first and second floor not filling

 

[terryplumb]

You could try draining and refilling,if that fails back fill the system with mains cold water.
What do you mean by " bib piping " ?

 

[JackK]

You could try draining and refilling,if that fails back fill the system with mains cold water.
What do you mean by " bib piping " ?

Sorry that should read big pipeworl - More than 22mm pipe work to radiators

Ill try a drain down thank you

 

[JackK]

I drained it down twice and there is still an airlock on one horizontal pipe which is so annoying

Anything else I can do before a plumber has to come (who will probably say he cant do anything because the pipe is steel and not copper)

 

[gas112]

as daft as it may sound try removing bleed nipple and get your mouth around end of rad and try sucking and blowing it can shift air locks