So glad to see this resource, it's so difficult to find information about warm air systems these days.
My Balmforth BD30 has been installed since the house was built in '86. We're quite happy with warm air, and don't really want to change. I have the manaual for this unit, and I've serviced it (which is basically just cleaning it) according to the instructions. For the most part, everything's fine, I serviced the blower motor and changed the motorised programmer for a digital one.
Recently though, we've had trouble with the pilot going out repeatedly. We managed to get it lit again, but it's a yellowy flame and now the inside of the burner compartment and surrounds are covered in soot. That means incomplete combustion and we've turned it all off.
I don't really want to replace the unit, although I know that there are drop in units available from Lennox, Johnson and Starley etc, because I'm sure this is just a question of replacing the gas valve and thermocouple etc.
I'd welcome opinion, and any advice you may have. Also it'd be great to have some personal recommendation for trusted tradesmen in the Guildford area.