Help! New to gas and having serious problem. Tried replacing Honeywell digital thermostat batteries, tried reprogramming all temps multiple times. Turned off thermostat, gas keepis running temp at 80 degrees. :furious: Finally out of deperation and perspiration, I had shut off the furnace switch. I must leave for work now and I am not looking to waste more costly fuel in having summertime temps in my NY home. Can anyone help? The gas furnace is a HydroTherm HC-125C, not sure how old.