banging 3 way valve

[pw21]

The system is open vented with an f&e tank in attic,
But when ever the central heating is turned on there is a loud bang (or knock) from the 3 way valve in the airing cupboard.

But no noise at all when just hot water is selected.

Any advice gratefully accepted.

pete

 

[D_Hailsham]

when ever the central heating is turned on there is a loud bang (or knock) from the 3 way valve in the airing cupboard.

But no noise at all when just hot water is selected.

The valve does nothing when just hot water is selected; which explains why it is quiet.

Is it a single bang or does it make the noise all the time the heating is on?
What if you have heating and hot water on at the same time?

 

[pw21]

when heating is selected it's just one single bang.
- thanks

 

[Soggy_weetabix]

The Honeywells can sometimes 'bang' on return to h/w.

What model is your m/v?

Dave

 

[D_Hailsham]

The Honeywells can sometimes 'bang' on return to h/w.

But the OP says that his valve is banging when it goes to heating!

To the OP

The three ports are labelled A, B, AB on the valve body. The AB port will connect to the pump. Can you say which port connects to the hot water cylinder?

Also give valve make and model as SW requested.