Boiler only runs for few minutes then stops.

[roosie]

The boiler lacks any water circulation and is cutting out on its stat. Is it an open vented system, I would guess it is and the F&E tank is empty, not getting any water to fill it.

Yes ots open vented , ill get in loft tomorrow and see if there is anything on the tank

 

[roosie]

check for a blocked cold feed, you will need a good magnet to test

OK, i have been in loft , what do you use magnet for ?

I have a small and large tank , both have plenty of water in , pushed float down and water does feed when pushed down.

I have drained the radiators using main drain pipe downstairs, then I have openable feed pipe and the radiators don't seem to be filling back up.

 

[Harry Bloomfield]

OK, i have been in loft , what do you use magnet for ?

I have a small and large tank , both have plenty of water in , pushed float down and water does feed when pushed down.

I have drained the radiators using main drain pipe downstairs, then I have openable feed pipe and the radiators don't seem to be filling back up.

You have blocked pipework then, probably the pipe down from the F&E tank is blocked.

The magnet, will not be attracted to you copper pipe, but it will be attracted where there is a lot of magnetite (rust) obstructing you pipes. Magnetite is a result of steel radiators rusting from the inside. It is a means to check a copper pipe for blockages, without physically disturbing the pipes.

 

[ianmcd]

yep the outlet of the small tank will be the water feed for your system, if a magnet attracts at any point(usually where it connects to the system) then that is where the blockage will be