Damp basement?
Sounds like all those fittings are corroded in.
Righty>tighty
Lefty>loosey.:vs_bulb::wink2:
I would imagine it would be, although it didn't feel damp today. However, there was no apparent corrosion on the surfaces of those particular items, but I reckon the threads could still be susceptible, maybe?
Utility room is 10' x 10' with concrete floor originally, that's now chewed up concrete floor (gravely-like in places (maybe they have, or had, water problems coming thru the old concrete block walls. Lots of dust down there. Burners (interior, bottom surfaces) had a clinging-type coating of dust underlying a thin layer of loose dust. After they were cleaned, no more snap, crackle & pop. Zero.
Manifold pressure wasn't measured, because partner was depending on my manometer, but it wouldn't read correctly. Not sure why, but maybe cause it was sitting in a canvas bag, located in the path of a cold draft last night. Flame characteristics were good. New one (little use, I mean -- over a year old). Fieldpiece SDMN-5 or something like that
Prior to the chimney blockage being cleaned, the shelf, I call it, which is apparently a horizontal heat shield (or maybe it's just a shelf for the rollout switches and their wiring) indirectly located over the burners (in between the burners and the gas valve that's on top) is no longer HOT, at least at. and near. its front edge. It seems too much heat from the blocked flue connection to chimney was backing up to the extent of abnormally heating up that shelf.
Burners and other parts had a clinging-type coating of dust. Had been watching for flame disturbance at blower ON point, during initial stage of checking out unit, but no flame movement.
Also pulled the A-coil out of plenum (not being used, no line-set or condenser unit on site). It was actually sitting crooked in plenum, causing the bottom-front face of plenum panel to be improperly joined with the sloped panel immediately below it, bowing it out some at the S-lock joint, which was a bit loose and taped to compensate, apparently.
All is apparently hunkey dorey at this point.