Vaillant combi boiler. Pressure Gauge

[davidk65]

How do you adjust the pressure. Having been away for a few weeks, on relighting the boiler, the pressure gauge has dropped from about mid position on the dark gray section of the gauge and is now in light gray section. Looking at the paper work for the boiler it says that if the needle is in this position, 0.8 bar, the system should be filled with water. Problem; it does not say how to carry out this task. Is this something that can be done without getting an engineer involved?

[terence7556]

filling it is done with a filling loop, which has a valve to open to admit water into the boiler .
it should be disconnected but quite often is fixed in position.its a small length of flexible braided pipe with a valve to open/close
your potential problem is where did the water go in the first place? is it a leak, or some pressure relief valve opening , which may mean a call to an engineer after all

[davidk65]

Thank you for your reply, which I found very helpful. I have found that there is a permanent loop device fitted to the boiler which has allowed me to fill the boiler i.e. the needle on the pressure gauge is now about midway in the dark grey scale when the boiler is cold, but moves up a little higher up the scale when the central heating is on .
I will keep a watch on how this goes over the next week before taking further action.
I wonder if the drop in pressure could be due to the fact the boiler was turned off whilst I was away, a period of about 4 weeks?