If you have a fan that starts up before the boiler ignites , then there is also an AIR PRESSURE switch.
The problem may be due to a partially blocked plastic pipe between the switch & fan.
It goes via an inline metal restrictor ( inside the plastic tube) that can block up.
Remove the tube and suck/blow so that you can hear the Air Pressure Switch clicking...then replace the tube.
A very common Netaheat fault....on the boilers with the fan + pressure switch !
Beware scrapping the boiler as most parts are still available (Ebay etc) so don`t jump to any expensive conclusions.
(and don`t believe what the CH engineers or Gas Board tell you. These old boilers are built to last....more than 28 years if necessary!)
chas
January 2010
howtomendit.com for free repair help, information and advice.
