The standing pilot gas furnace uses a standing pilot to light the main burners. Many gas fired water heaters have the standing pilot ignition system. The standing pilot gas ignition system is sometimes referred to as a safety pilot because it increases the safety of ensuring the main burners are lit. The standing pilot can be used on a natural gas ignition system or an LP ignition system. These heating ignition systems are older and are slowly being replaced by the more modern and safer electronic ignition systems.
The standing pilot ignition system uses a thermocouple to detect the flame on the pilot. As long as the tip remains hot and the standing pilot thermocouple is in good working order the system works good and heat is provided when the thermostat calls for heat. The thermocouple is the device which proves the pilot flame.
If the thermocouple is not hot it will automatically release the primary valve inside the standing pilot gas valve. If the primary valve in the standing pilot gas valve then the secondary gas valve inside the standing pilot gas valve remains closed. The secondary valve is the valve which feeds gas to the main burners. Therefore, if the primary valve is closed then the secondary will not get gas to it. This is how the standing pilot gas valve has remained a reliable safe gas ignition system for many years.
Standing Pilot gas valves can be found in Natural Gas Furnaces as well as LP Gas Furnaces heating Systems. Additionally, there are millions of gas fired water heaters that utilize the standing pilot gas heating systems.Gas fired water heaters can use either the standing pilot gas valve or electronic ignition gas valves that connected to a solid state electronic ignition system. The majority of gas fired water heaters, however, use the standing pilot gas valve. Standing pilot gas water heaters typically use a thermocouple rather than a thermophile for proving the flame at the pilot light.
A standing pilot gas valve has the main gas feed supplied by the large gas pipe, the pilot gas feed that feeds gas to the pilot assembly, and a thermocouple or thermophile. Main gas is fed to the valve but the main valve inside the standing pilot gas valve remains closed until two things happen. First there must be a call for heat from the main thermostat that controls heating in the structure being served by the gas furnace. The thermostat is usually set for a comfort level of the occupants of the structure to remain comfortable. Secondly for the furnace to fire the thermocouple or thermophile must prove there is a flame at the pilot light before the main gas valve inside the valve will open and fire the main burners. This is safe and standing pilot gas valve have been operating safely for decades and have proven to be safe.
Gas furnaces, gas water heaters, and gas fired boilers that include both propane fired systems and natural gas fired systems typically use thermocouples as the method of proving the flame. Gas logs whether they are natural gas gas logs or propane gas logs typically utilize a thermophile although there some systems out there that have thermocouples.
Many standing pilot gas valves come with a conversion kit to convert the gas valve from natural gas to propane or from propane to natural gas. It is important to follow all manufacturers instructions when converting the system over from one gas to another especailly ensuring the proper pressures are set for the gas valve.