I have an old Clare megasave, and it has been giving me some strange issues lately. It was serviced just last spring, and the tech ended up replacing the sequencer, igniter, and ignition control module (which was the actual problem)
Firstly, a problem that has been happening with the new Honeywell UtilityPRO thermostat is that after switching it to heat yesterday, it will go blank every 10 minutes. From looking around the net, I found the cause is likely to be the temperature limit switch tripping and cutting 24V power to that stat. Makes sense, as my furnace has been running VERY hot in the last year or so. SO hot that the ducts are untouchable. The tech told me that was normal, and I'm certain it is not, as it has never run that hot. The other thing is that when I called in about the limit switch tripping, they said it was normal and that it was the peaksaver thermostat's problem, and that I should call my power utility company to get it looked at. Not convinced.
Another issue is that both this utilitypro, and my previous Honeywell FocusPROTH6000 series appear to kill the heat too early. By too early I mean the fan doesn't get a chance to start yet, and the thermostat just aborts the heat on signal and the furnace ends up sitting. Even more strange is the fact that the fan will sometimes turn on a few minutes after the furnace stops. Thermostat idle and the fan will turn on by itself a few minutes following the aborted heatup.
Any advice about what I can do/what I can tell the service tech to check? I'm under a service plan, but the techs seem to be more willing to just do the bare minimum, say everything is fine, and then try to sell me on a new furnace