However, the best pick for a highly reliable flame detection would be the application of a furnace flame sensor rod (see below). Gas flames are conductive and act as a rectifier like a common diode.

Dear Jerry: I remodeled a first-floor, single-bedroom apartment in a 100-year-old house eight years ago. I fully insulated the unit, R-13 walls, R-38 ceilings, new low E, argon windows and ...