[donklein]

This trane gas heater was installed in 2007 and starting 2 years ago, intermittantly, the heat will come on, then shut off after 30 seconds. According to the thermastat, the heat is on following schedule. No error codes. Turn off the thermastat for 5 minutes and most of the time it will come on according to the thermastat. Trane techs have been out here at least 12 times in the last 2 1/2 years, replacing pressure swithc, cleaning, even new thermastat. Replaced entire heat exchange, had been set up for natural gas instead of LPL. Nothing seems to correct this problem.
Now it has start coming on whenever... It is set to come on at 7:15am (66 degrees), but will come on at 4am when it is still 62 degrees even though it shouldn't come on until it get to 58 degrees. All different times during the early morning. Durning the day... no problems! No one has been able to correct this situation yet. Any thoughts?