Problems with Hot Water with Vaillant Boiler

[Kelly Jo]

I have just moved into a new house, which has a Vaillant Boiler. I am having some trouble at the moment because the hot water only seems to work when the heating is on. However it occasionally does work with the heating off. I have noticed that the pressure gauge is below 1 when this seems to happen and I was given a key to adjust the pressure if need be but no instructions on how to do this? Also I'm not sure if it is the pressure that could be causing this or something altogether different (someone has mentioned to me the diverter valve may be faulty?)

[megnom]

Unless you are Corgi registered it is dangerous to meddle.
Call in the experts-- it could save your life