Heater does not shut off when it reaches set temp.level

Does the furnace shut off at all, or does it just run continuously? Is it just the blower that runs, or are the burners ignited? The more info you can give the better we can try to help.

We have a gas heater that is always on. The A/C and cooling are on Forced heat. The thermostat is a Honeywell Non-programmable, Model 3000Pro TH3210D1004. It is only 3 months old. The cooling shuts off okay when set on AUTO, but not the heat. It keeps running beyond the SET temperature level.

Thank You for your response !

Read through the instructions on the thermostat and look for a section on the HEAT CYCLE RATE. Make sure it is set to match your furnace.