this is with induced draft and you can see the supply fan into the house pushing the induced forced burner gas all over,when the tech popped the access panel the rollout switch wires were melted.even with a standard burner any flame change when the supply fan comes on is an indication of holes and or cracks...
The Following User Says Thank You to biggles For This Useful Post:
Pretty dramatic indication of a cracked exchanger.
The trouble with "even with a standard burner any flame change when the supply fan comes on is an indication of holes and or cracks... is that many standard burners can turn yellow from the dust kicked up by the supply fan when there is a heating outlet in the vacinity of those burners and the furnace doors are removed.
This initial dust kick up is used by some companies in my area as the proof of the need for a furnace change. Obviously if they showed this to the homeowner 30 seconds later the flames would have returned to blue and there'd be no proof of a cracked exchanger.
Guess it comes down to one's definition of a flame change.
i would never judge it by color change its the flame movement that is the indicator like you said too much dust and air borne crap check out that other one on the YOUTUBE right side list with the rolling burner without the ID