Recently installed a noma programmable thermostat and same worked fine for four days but today the furnace would not shut off despite the temp rising to 78+F. The temp was set for 67F. The only way to get the furnace to stop running was to shut it off manually. How do I correct this problem?

Toss the Noma thermostat they are junk. Get a Honeywell instead.

I agree with hvac1000.

Try disconnecting the red wire at the thermostat and see if it still runs, if it shuts down then its your thermostat, if it continues to run then your problem may be a short in the thermostat wiring or a problem with the gas control valve. Good luck, Mike