the FL keeps flashihg on heater and large bang when ignighting any sugestions

lisa an steve, March 2011

LF
flame failure
likely causes
warped ignition electrode failing to spark at correct ignition sequence [would explain loud bang]
normally caused by blocked condensate trap
ignition electrode needs replacing
ionization pins need upgrading
condition of combustion insulation needs checking
condensate trap & heat exchanger sump need cleaning
& testing for adequate drainage of condensate

manwithnoname, May 2011

Whatever suggestions that could be made are gas related, therefore you need a gas safe registered engineer to look at it.

Carefree, March 2011