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Originally posted by Wadders
Sounds to me like your boiler is kettleing (ie boiling the water because its not circulating)
reason it wont fire when you tried it the second time is because the overheat stat has kicked in. Could be a couple of things boiler could be airlocked or pump is not circulating. Try tapping the pump with a hammer a few times, also take out the central silver screw cap and see if the shaft is actually turning.

Pump should run for a while after the boiler has shut down (pump overun) pump is wired from circuit board in boiler.

there should be a valve either side of the pump which in theory you can isolate to remove the pump without draining down, but in practise they're usually shagged.

U2U me with your number if you like, and i'll try to explain a bit better. I do this for a living BTW

Al.


Originally posted by russbost
Last night central heating & water system started making horrible banging noises in pipes, sounded like tons of trapped air. Banging was so bad it actually started a minor leak by the pump, I thought something was going to explode!!! Obviously shut the system down, tried bleeding air out of everywhere I could think of, left it overnight & tentatively started up again this morning, as soon as the boiler fired, horrible banging noises in pipes again. Tried again just running hot water, no heating, boiler didn't fire but pump appeared to be running, left like that for a while, no noises, but boiler still not fired, pump seemed to be very very hot, tried heating again, boiler still doesn't fire. Turned everything off including turning thermostat down, but pump still appeares to be running (humming) only way I can turn pump off is to cut mains power to the pump/boiler.
System is Potterton Suprima 80 with separate hot tank about 8-9 years old.
I can't get a plumber anywhere, I'm guessing the pump is Bolloxed? Am I right & how hard a job to change - where do i drain the system down from?
Any help greatly appreciated!

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