rad not fully refilling

[repro28]

I am trying to re-fit a rad after decorating and it is at lowest part of system as it has system bleed valve on one pipe. It only refills about a quarter of the rad and no hissing from bleed valve. I have turned off all other rads and tried turning on pump but nothing happens. It has a TRV on it but this seems OK. Any ideas ?

 

[chrishutt]

Is it a sealed system or an open one (.e. is there an open tank feeding heating system)?

 

[repro28]

It is a gravity fed system with an open tank.hot water cylinder and back boiler behind a gas fire.

 

[kevplumb]

is the tank filling

 

[chrishutt]

Are you sure air vent on rad is not blocked? If OK, disconnect rad valves from rad and check that each will deliver free flow when opened.

 

[repro28]

The tank is full. First rad went on OK but not this. I will take it off again and check the flow of water through it....cheers

 

[kevplumb]

turn the valves off
remove the bleed screw poke a pin in

 

[repro28]

It was a blocked bleed valve. Thanks for the advice. Next time I will try the easy things first instead of looking for big faults.