Vaillant Turbomax bangs when hot tap turned on/off

[TQ_uk]

My Vaillant Turbomax combi has started making an alarming (single) bang when any of the hot tap (kitchen/bathroom) are turned on or off.

It did this last year shortly before the pump packed up and we had a new one fitted. All was well until last month or so when noise has returned.

I *think* it firstly only did it when central heating was on AND hot taps turned on/off but now seems to do it even if c/h not on.

Pressure seems ok, about 1.5 bar at normal temp (boiler has mode where it keeps water at certain temp - forget the technical name)

Any ideas, as it sounds like its on its last legs?

Thanks in advance

 

[gas4you]

I take it you mean a hydraulic, metallic bang and not from the burner?

Sounds as though it could be the 'usual' diverter valve fault with these turbomax's.

 

[TQ_uk]

Yes, not an 'explosion' type bang - more like something 'in the pipes' (technical term ) but emitting from boiler

 

[kevplumb]

err its got a swollen ball (ohh err misus)

in the diverter

 

[TQ_uk]

Easy (read cheap) to fix?