Banging from Motorised Valve

[andymck]

Hi, my home hot water and central heating system is implemented with a Danfoss Randall Fp715 si HPP system ( see link here http://www.plumbitcentre.com/epages/BT3 ... cts/000006)

Ever since it was fitted ( by the builder ) we have been getting sporadic banging noises from what appears to be the motorised valve. It mostly seems to occur when the CH comes on or when it goes off again and can continue for hours on end, getting progressively worse. The noise can be heard throughout the house.

The only way to stop the banging noise is to manually switch on the HW and leave on for about 10 seconds and await for motorised valve to move position ( sorry i am not a plumber, heating engineer etc and dont know the correct terminology here ).

We have had the motorised valve replaced twice and still no change and have had numerous plumbers out to look at it. They all say its the valve, replace it and same story. I have noticed that no one really seems to have clear knowledge of how all these things are supposed to work. Could it be the port the motorised valve connects to ? Could the thermostat be incorrectly wired ?

Our heating system is an oil based sealed System with a conventional boiler. The pressue is set to 1 bar, 0.5 bar at rest.

Any help or input would be much appreciated. I can upload pictures of the wiring of the WB12 box and video of the banging and how we stop it continuing.

Thanks

Andy

[akaal]

hi
what you said from that it looks like it is flow problem