I have Hail gas furnace with electronic ignition and Honeywell
thermostat. 50% of time when the temperature drops to the fring level,
the thermostat shous "system on", while the furnace does not fire up.
Usually when this happens, temperature will continue to drop further
until I go down and turn the main switch off and back on. At this
point it fires up allright. Called service several time, they have no
patience to wait until it happens, replaces the gas valve - no result.
Advice would be greatly appreciated. Thanks,