I have some more info , it is a hot surface igniter,model # 2755-766 I have a night set back t.stat. On the furnace it states that with this t.stat I need a isolation relay what does that do? I not sure if I have one, I cannot remember if I installed The t.stat after the house was built or the contr...

the burner will shut off even though sometimes the burner will stay on while blower cycles.

Hello all, I have a coleman 70 furnace about 23 years old. My problem,I cannot keep it running.The temp wiil drop below t.stat then I have to drop temp on t.stat then bring it back up,the furnace will start run between 2 sec.-40 sec it will cycle like this between 3 and 10 times.After doing this for...