Central Heating Noise

[garrytheskate]

HW off, CH on. When the thermostat trips out there is a very loud bang in the system. This does not happen every time but always happens when tripping out. Bled the system, all radiator valves open, boiler 4 years old. Any ideas?

 

[mcmoby69]

Yep.
Say please and thankyou.

 

[oilhead]

My crystal ball tells me you have acombi, and the diverter valve is changing over. Don't worry.
Now say please and thank you!!

 

[garrytheskate]

Thanks for that but its a two way valve. What I have noticed though is the valve has been fitted the wrong way round. Would this make the noise.
Thanks

 

[RigidRaider]

I had this with my Y valve. I changed it but the bonk noise continued so I complained to Honeywell. They asked for a photo of the installation, which I sent and they replied that the valve had not been installed according to their instruction that there should be a minimum of 6 inches of straight pipe run on each of the three sides before any bends. They spouted some claptrap about laminar flow of water etcetera etcetera, which sounded like an excuse for a poor design to me.

When I looked inside the old valve (which was only a couple of years old) I thought the bonk was being caused by poor control of the hard rubber ball, which swings around opening and closing the ports. It was quite a sloppy fit on its arm and I believe that the slop allows the ball to bang into the port rather than close it progressively. We have learned to live with the sound.

 

[garrytheskate]

Thanks for that. I have finally been next to the valve when its banged and its definitely the valve. Have emailed Drayton to find out if fitting the valve the wrong way round is the problem. Will post details if problem solved.
Many thanks

 

[ianmcd]

yes if the valve is the wrong way round it will clunk when closing

 

[garrytheskate]

Thanks. Off out to get a new valve!!

 

[garrytheskate]

Fitted new control valve, NO noise. Thanks to all who replied to this thread.