I've got a 5 burner Trane (7 years old) where the stage 1 heating fails and the stage 2 heating works fine. If stage 2 comes on first and drops to stage 1, then stage 1 works fine (all 5 burners remain lit).

In the stage 1 failure mode, the ignitor lites (near burner 1) but only the first two burners ignite. The ignition sensor appears located at burner 5 and after a few seconds the gas shuts down. It then recycles in this mode until it seems to lock up permanently. A power on reset will cause it to go back in to recycling failure mode.

The installation manual, describes adjusting the stage 1 to 1.4 - 1.7 W.C using a "manifold pressure guage". Stage 2 is 3 to 3.5

My thoughts are, unlikely igntitor problem, possible regulator problem or aging regulator drift for low pressure.

My first reaction is to go in and check and adjust the Regulator low pressure to spec - but why has it become "too low"?

Considering this is probably a 1 time adjustment, what kind of meter can I buy and how do I use it? I see digital manometers ranging from actual $19 water filled to digital $245.

Also I dont know if the burners are supposed to lite sequentially from burner 1 to 5?

any thoughhts on this?