Banging Ecotec pro28 - There's no *** quality anymore!!

[timbalcombe]

Boiler is just over a year old interms of installation.
When the heating is not called for anymore eg at temp, when the boiler switches off the gas supply, there is a a bit of a bang.
I could understand if it was the otherway round - on ignition, but this is strange.
Vaillant have had a look at the gas pressure/air mix (had them round as the aqua sensor rattles on DHW - they never fixed it), and all is well.
Any Idea's, call them back?

Their cover scheme with yearly inspection is something like £180/year.
This is a rip off in my opinion as it doesn't cover plumbing. BG charge £15/month for the whole lot. Anyone have any thoughts?
It doesn't fill me with confidence that I receive an email from them, after I sent them a polite email saying there was no warranty info on their website, they replied, "sorry there are no engineers in your area"
THICK OR WHAT?
I think its a bit ironic they offer only a years warranty on something called a PRO!

 

[Strachan]

Believe it or not the pro model is the budget version of the ecotec range. Smaller dhw heat exchanger, single speed pump and they`ve even scraped that exta couple of quid back by not putting a cover flap over the controls. I`ve not had any problems with the ones i`ve fitted, only installed plus models though. You sure it`s the gas shutting off that makes the banging noise?

 

[timbalcombe]

can't be sure, but when the room stat kicks in, and switches boiler off, the bang happens.

 

[Strachan]

I guess it doesn`t happen when you turn the dhw off?

 

[timbalcombe]

no it doesn't. is that relevant?