> If the control board for the furnace is old, it's possible the sensing
> circuit is right on the edge of normal current and the flame failure is due
> to that. Also check the grounding of the pilot assembly and all wire
> connections. I'm sure many houses with multiple smokers of cigarettes would
> be far more likely to have problems and I have never heard of it.
New furnace less than a year old. Furnace is properly grounded and has DSI (no pilot). The flame sensor literally gets a coating of (film???) approx. every 30 days and loses flame signal