I have a Brivis Classic 2P Wombat 26 gas furnace in a place we moved into late last year. We didn't really experience winter then so hadn't had much of a chance to use the ducted heating much.
Now with the cold weather coming around, I started to pay close attention to the behaviour of the system. And something about it's startup seems odd.
When the thermostat sends its signal to turn on the flame, it starts its striking sequence and creates the typical blue flames. But immediately as that happens there is an audible click (same sounds as when it would natural get turned off) and the flames turn off and the fan to the ducts kicks in. Seconds later, as the fan is already running, the striking recommences and the flame once again is lit. This time it stays on. Then the system functions as normal.
This behaviour is not consistent either. So once the heating is going, then turns off as per the thermostat, then later gets a signal to turn back on, the process is as normal. No instant fan, no instant flame off. But if I were to leave the furnace off for a while, and turn it back on later in the day, the the initial ignition experiences the strange behaviour. That being said, it sometimes starts up as normal as well, so there's no consistency to it.
Now for a bit of extra info. The reason I started to pay close attention to this behaviour is because I installed a Nest thermostat to replace the old one. When I noticed this happening, I undid everything and reverted back to the original. But the behaviour still persists. So I don't think I tampered with anything. For all I know, this could've been it "usual" behaviour long before we moved in...
Can anyone explain this behaviour? The only harm it's doing right now is letting out cold air for the first couple of seconds. But if this is a fault, I'd love to know if there is a solution.