I have a Powervent on the furnace. This powervent I have had on the furnace for the past two seasons now going on the third. The manual for the 140 specified a .04 draft. I always check the draft at the beginning of each heating season. If the powervent is too dirty and has let the draft drop, that might cause a positive pressure in the furnace thus tripping the safety sensor. I will have to check to see how dirty the powerventer is.
Interesting, I did not check those. I did look at the Fields damper and it was holding steady as it has all season as well as the past two seasons. I have not cleaned it since I started the 140 this year. I usually do not need to clean it all season. If I had my manometer with me I would have checked the draft.
Has anyone ever heard of the safety sensor on the 140's going bad? Just thinking. If you guys have any ideas I'd love to hear them. Thanks.