Honeywell CT3300A Thermostat – 25 min timeout

22:12: ______________________________________________________________________ Hi, I have been trying to troubleshoot what I thought was a furnace problem for 3 days now. I have a Lennox furnace about 2 years old (GVA60 series) and have found on cold days it runs a max of 25 mins and shuts down in the morning. The unit waits 2 mins and restarts, this repeats until the house is brought up to temp. The furnace has on-board diagnostics and all lights show correct operation. I spoke to my brother who has a very old furnace with no electronic computer and his unit with the same make of thermostat does the same thing. I now feel better that its not my expensive furnace, I don’t see this feature listed in the thermostat manual. Has anyone else noticed this? — pmoyer [this message was edited by pmoyer on Mon 5 Dec 22:14] Replies: moondog “Re(1):Honeywell CT3300A Thermostat – 25 min t” , posted Tue 6 Dec 03:24 ______________________________________________________________________ Are you saying it will run for 25 minutes to satisfy the thermostat’s setting? Is it a two stage furnace? Are you setting the tstat down at night? How long does it run during the day? Does the unit stay in low fire (if two stage heating) for that 25 min. Still under warranty? pmoyer “Re(2):Honeywell CT3300A Thermostat – 25 min t” , posted Tue 6 Dec 15:21 ______________________________________________________________________ Basically @ 6 am my thermostat is set to move from 64 to 68 degrees (this usually takes about 1 hr total). The unit fires @ 6 kicks the furnace in low for 10 minutes then the furnace’s computer signals goto hi heat and is allowed to run by the thermostat for a total of 25 minutes. The house has come up to maybe 66 degrees, the thermostat then tells the furnace to shutdown then it waits 2 minutes then tells the furnace to fire up again. Usually by the second cycle the house is up to temp and the issue no longer exists. I watched the thermostat this morning and the display @ the end of 25 mins shuts off heeat symbols waits and restarts. The furnace is a 2 stage unit and has a jumper to operate with a single stage thermostat and uses a 10 minute timer to tell itself when to enter high heat. Basically the thermostat by shutting down is defeating my furnace’s second stage. — pmoyer