vaillant 837 pump on when cold tap runs?

[dyslexicwinker]

Am i right in thinking this is just air in the system or something more conspicuous?

Also the pumpwa s very noisy to start leading me to believe it could be the above?

Any help would be great

thanks,

 

[simond]

I should call back the original installer

Or give Vaillant a service call, it'll still be under warranty, won't it?

 

[Deleted member 105431]

if you get nuisance startup after cold tap is run then you have a dead leg of pipework which is an installation fault. A non return valve on the dhw outlet of boiler should cure this but won't be done under warranty. Call the installer back.