I have a turbo vaillant boiler. the needle on pressure gauge was below 1, so I added water to it taking it to just below 2 on the green bar. The following morning it was back to just below 1 but when the heating came on it rose to the red bar. What is the problem? What should I do to ensure it does not fluctuate to extremes?

Amar, November 2009

sounds like the expansion vessel needs recharging unless its got a rip in the diaphram in which case it needs replacing its the large usually red metal oblong on the right as u look at the boiler inside the case it has what looks like a bike valve on it this is where u pump it up, take the cap off push the pin quick if it lets water out then vessel is no good if it does nothing then u can replenish it. to do this get a footpump with a guage telling u bar pressure dump all the pressure in the boiler using prv pump up the expansion vessel to 1.5bar then refill system bringing the pressure in boiler back to 1.5bar

sean, November 2009