Original message
| hamprancer | "Pilot Not Lit - Burner Limit Circuit Open" , posted Wed 1 Oct 11:02:  
Waking up to a cold house is always fun. The blower runs, the fan runs when turned to "ON", but when I looked, the pilot was out. I tried to restart it (auto-igniter) a couple of times with no luck. The diagnostic light indicates that the "Burner Limit Circuit (is) Open". I don't have any documentation for the furnace (moved into the house a couple weeks ago).
I have a Tech-4 True Blue 90, about 13 years old.
Does this mean I need a new igniter?
[this message was edited by hamprancer on Wed 1 Oct 11:06] | | Replies:
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| Schock Therapy | "Re(1):Pilot Not Lit - Burner Limit Circuit Op" , posted Wed 1 Oct 23:30  
That probably means that one of the temperature limit switches has tripped, either the high limit, the roll-out switch. The high limit will trip if there is not enough airflow over the heat exchanger due to a fan failure, a plugged filter, or even from power loss while the unit was heating. The rollout switch trips if the burner flame and hot gasses are rolling out into the cabinet instead of through the heat exchanger and up the flue. This could be caused by a failed inducer blower, restricted flue, or a cracked or plugged heat exchanger.
It's only a shock if your not expecting it!
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