buickanddeere
Super Member
If your house gets to cold b-4 the propane faf kicks back on something is wrong ( t.stat or t.stat placement. You shouldn't see anymore than a 1-2 temp difference from (set temp.) B-4 the furnace switches back on.2 deg would be an old mercury style t.stat. Newer ones about 1 deg.
Problem is the person #1 who sized the LP furnace too large . #2 they did not use a stat with a derivative function and too much dead band.
Lots of furnace installers, sad few however with a clue about theory and control