b5a5d860_for_any_fuel_gas_fired__boiler__Item
[Safety] The flow control valves for natural gas and combustion air are linked mechanically Â– as one is opened or closed, the other does the same. [Reason] If too much or too little combustion air is supplied with the natural gas, the flame can go out. [Item] 
Linked Natural Gas and Combustion Air Valves
Safety controls for any fuel gas fired  boiler
Item