On 1/23/2021 8:45 PM, canard wrote:
From past experience, it is the burners that are dirty. Just turn the
furnace off (electrically with the switch on the wall and put the gaz
knob to off and of course put the thermostat at the lowest setting. Get
a good light and a few basic tools and remove the burners and vacuum
them ir even better use a copper brush at the end of a drill to clean
all the burner's openings well. Replace, put the bottom door back if you
removed it (to push on the safety stop switch), put on pilot, relight
with a barbecue lighter, count to 100 and keep your finger on the pilot
buttin, when lit put on ON and then put your thermostat higher and then
listen and it should not bang anymore. If it does clean the pilot as
outlet and you can even try this first but if you pilot flame is good it
should not be the problem.


I have seen this when the pilot light jet is plugged, and the flame is
to small to quickly light the flame. It can be cleaned with a fine wire.