I hope someone will please help me. I have an oil fired, forced hot air system with 3 zones. We will come home from being out for hours or wake up the next morning, and there will be no heat. All three programmable tstats show they are calling, but the controller box next to the furnace has no led indicators lit. These glow red in normal operation when a zone is calling. Pushing the furnace reset button does nothing. If we shut off all the tstats, wait a few minutes, then turn them on one at a time, the system fires up like nothing was wrong. It will be fine for a few days, and then it repeats.