When I set the temp to say 68 degrees the furnace will come on after about 25 min. the temp will show about 10 degrees cooler than what it was. Why is this. When I set the temp to shut furnace off , after 20 min it will be about 10 degrees hotter. This is a new thermostat.

Return it to the store from which you purchased it & get a Honeywell or White-Rodgers thermostat. I've had nothing but trouble out of the Hunter stats.

Amen,to what Grady White said, I agree to what he said,Hunter tstats are junk