Having just drained my heating system to replace a number of failing radiators,I have re-filled the system but now find my boiler (Camray 2- oil) only runs for a brief time then shuts off .The upstairs radiators have been bled as best I can, all whistling air removed but no water has come out, downstais are all ok. I have a Honeywell motorized zone valve in the airing cupboard on the heating pipework, this was left set to 'Auto' whilst all the work was done. Hope this enough info for somebody to help, afraid its not my thing. Many thanks .
Simon

Simon Whitmore, February 2012

just to add, if you have a sealed system, you must leave the filling loop taps 'open' when purging the system of air using the hose method...and come to think of it, are you aware if your system is fed from an attic header tank, or do you fill the system using a filling loop? all combis are sealed systems....

mark properjob, February 2012

Hi, i'm an oftec engineer..
start again, and place the honeywell's manual lever locked into 'manual'...then connect a hose pipe to a drain-off cock on the system, and put the other end in a bucket outside.
open the drain cock, and let it run until ypu get no more bubbles in the bucket. then close off the drain cock, bleed all rads.
Then go around house, and close off the flow valve (thermostatic valve side if fitted) on all the rads that are heating up, thus forcing the flow to the airlocked part of the system. this always works. also, check circulation pump isnt whining, and unscrew the silver 'button' on its face until water dribbles out...could be air in the pump.
best of luck!!

mark properjob, February 2012

Need to have unit off and valves on manual with pressure up then bleed.

Old Guy, February 2012