vokera 20-80rs burner flame problem

hi people i wonder if anybody can help me with a problem i,m having , i have the vokera 20-80rs that had been fitted in a new house (being renovated) that i,ve bought , so it hadn,t been running for about a 9 months and had been off the wall but stored carefully b4 being put back up , i have got the boiler to fire up wether its the central heating or hot water needed but i cannot keep the \\\"call for heat \\\" on , as after a few seconds of the burners being lit the flame seems to go mad and get very high (as high as the main heat exchanger ) it,s like there is too much gas coming through the gas valve , the gas regulator outside the house from the mains has been checked as well as the pressure from the pressure test point on the actual gas valve in the boiler and both seem to be fine , this problem happens regardless of the thermostat settings on the actual boiler control panel , the burner will just not light and stay at a resonable level within the combustion chamber so i have to turn off the demand for heat so that then the burner cuts out leaving the pilot light lit still ........any help will be appreiciated.....

when you say flames are lifting high as the heat exchanger do you mean all flames are lifting off the burner complete?. if so the problem is with the flue , the flue is connected properly

mustang said:

the flue is connected properly

Click to expand...

is it?

Boiler fitted in a new house?>> This boiler, while well made, is at least 10 years old. How could it be fittedin a new house. My experience is that this boiler is (wrongly) removed and dumped for it to find a new home. I wonder if this is the case here.
Also wonder if the boiler (before installation) has been serviced in a similar manner that weargas listed in another post. This kind of service (call it overhaul) certainly puts the boiler back on its feet.