Honeywell Thermopile Generators have been a staple for self-powered heaters and hot water equipment for years. Measuring 35 in. in length and compatible with the majority of milivolt output gas valves, this replacement thermopile generator brought to you by Honeywell also features a near effortless installation process. Utilized in over a million appliances as a contractor’s preferred thermopile generator, Honeywell Thermopile Generators can be found in many of today’s self powered gas fireplaces.