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radiators won't heat up but pump motor is running

Posted: Mon Mar 05, 2007 10:33 am
by andymuppet
We turn on the heating and you can hear the motor in the pump running, but there is no movement, the radiators do not heat at all. Have tried bleeding them but no movement, have closed the outlets and opened the inlets fully to bleed, but nothing. Have cleaned out the pump. The boiler is working as we have hot water, just no heating. Can you please help?

Posted: Mon Mar 05, 2007 8:01 pm
by thedoctor
Take a look at the central heating projects on the website Andy. If the answer isn't there you can email the gas man from his website.

Posted: Tue Mar 06, 2007 5:48 pm
by marney
it might be the diverter valve

Posted: Tue Mar 06, 2007 5:49 pm
by marney
it could be the diverter valve?

Motorised Valves

Posted: Thu Mar 08, 2007 4:56 pm
by Cpt Nemo
Hi Andy
If you hot water (HW) then we can assume that your boiler and pump are OK.

The next logical unit to look at is either the 3-port valve, or zone valve - it depends upon which arrangement of motorised valves you have in your Central Heating (CH ) system.

To identify which type of valve you have you'll need to look at your system - the 3 port has one valve with an A/B input and two outputs an A and a B.

A zone valve system has two separate motorised valves - one controls the HW zone and the other the CH zone.

Let me know which one you have

Posted: Thu Mar 15, 2007 10:29 am
by colinmoore
Hi Andy,
I have two permanent cold radiators in my house.They have been bled on numerous occasions but still they remain cold. British Gas says that the system needs power flushing and would cost £600.00 or more. I'am quite capable of doing this sort of work myself, can you help me resolve this problem?
Colin Moore

Posted: Fri Mar 16, 2007 12:30 pm
by thedoctor

Posted: Sat Mar 17, 2007 8:41 pm
You can flush eack radiator out manually but if the system is badly sludged then the best way of removing the sludge is by use of a flushing machine. But you must be aware that there wil be an underlying fault causing the system to sludge and this will need correcting aswell oterwise the problem will come back.

Posted: Thu Mar 29, 2007 8:53 pm
by grizzlyadams
Check you pump is actually working and not just running. I had trouble getting heat to my radiators, took a good few hours to warm up and even then not very hot, plenty of domestic hot water though. Fitted a new pump and now they are good and hot in minutes. Just a well worn pump was the problem, it ran but wasn't pumping much.