Can anyone help me get my Vokera 28-80 rs serviced/repaired?

I know it's twenty years old, but I think it's a great boiler. The problems it has just now are: i.sometimes, only when I using the kitchen hot top, the boiler doesn't switch off after I close the tap; and
ii. the pressure is dropping and it doesn't really register until I turn on the kitchen hot tap at which point the needle on the meter jumps all over the place and settles somewhere around 0.5.
It suggests an air lock??? Any decent engineers in Glasgow that can sort it?

DavyMorgan, February 2011

Cant think what would cause your problem, DP who posts here:
http://tinyurl.com/63daskk
works in Glasgow and is expert in things Vokera, (or seems to me to be.)

c#, February 2011

Thanks, c#. It doesn't jump up when the heating is on, only when I turn on a tap. I do top it up regularly but it's got a leak somewhere!! I'm looking for someone in Glasgow to service it. Know anyone?

DavyMorgan, February 2011

This sounds unhealthy, the pressure should never do that, it should never be operated at low pressures as the water in the heat exchanger could boil. Top up the pressure using the filling loop. If the pressure shoots up when the central heating heats up you need to recharge the expansion vessel. Do it now, if you have a car tyre pump and access to the top of the big red expansion vessel at the back of the boiler, do it yourself, google it Its time you got it serviced.

c#, February 2011