visionset wrote:
New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

--
Mike W

Hi Mike,

Massive coincidence... I was just searching the forum as I have this
issue and your post appeared!! I am getting similar symptoms on my
newly installed Glow-Worm combi. I have an engineer visiting tomorrow
about a separate issue (loud rumbling) but I will ask him about this as
well. Watch this space!

J