"Veteran" wrote...

I guess the q. remains. what part of the pipe is critical when it comes
to the read out. we have a magnetic thermometer that has a creosote
range, then a "burn zone" 125 to 300 degree F. and then an overfire area.

In that case, it should go above the damper. Creosote buildup is more of a
problem in the chimney. There will be little buildup before the damper, because
it will burn off when the fire is hot.