3100 00011219 is a Honeywell part number for a modulating gas valve. It is a multi-purpose gas valve designed for use with natural and propane gas, that modulates the flow of gas to provide automatic temperature control of variable furnaces, rooftop heating, and other gas-fired applications. It features robust construction for durability and reliability and is designed to meet UL, CSA, and AGA standards for installation in vertical and horizontal locations. It has a separate low fire modulation, a manual reset high limit, gas pressure regulator, and manual gas shut off. Additionally, it is equipped with an LED indicator that validates flame on each ignition cycle.