Baxi bermuda 551 Supplying hot water but no heating.

[adaervon]

Hi, hope you can help. I have had a baxi bermuda back boiler that has been working fine until yesterday, it suddenly stopped supplying hot water to radiators. I called in a plumber who advised me to replace a non return valve which he was convinced was the fault, I did this with the valve in the same direction as the original (up) and refilled the system. I still have the same problem: Plenty of hot water coming from taps, no hot water going to radiators. I noticed that the pipe I was working on is warm at the boiler end but gets cooler as you go up just below the replaced valve.I then turned off the system and bled rads. I turned the boiler control to high, room stat up to max and have put the pump to no 3 setting (was originally on 1). Boiler fires up but keeps cutting off as if the required heat is reached, please help so we can have a warm Christmas. Thanks

[buildersmate]

Silly question, but is the pump actually moving water?
How do you know? - just because it may be vibrating doesn't mean it is shifting any water.

[tezestwing]

I agree with BM I assume it is a old system ?(bit more info would help) that has gravity fed hot water to the cyl internal coil hence good tap hot water, the other central heating side will be pumped if you are able to drain down and fit a new non return valve in I suspect the flow side of the gravity feed then you should be able to replace a same for same pump no drain down required but use new fibre washers hth Tez