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Black pipe gas line reduced at the gas valce.

In the picture below is a gas fired hot water boiler, the silver thing the black pipe is connected to is a Honeywell gas control valve for the boiler. The black pipe is the gas pipe supplying gas to the gas control valve. The problem here is the black pipe coming into the boiler is smaller then the inlet size of the gas valve. Gas control valves require X amount of gas, a smaller gas line may not provide enough gas for the boiler to run properly, causing a possible carbon monoxide problem, carbon monoxide is a gas that comes from any fuel that is not burning properly. if the gas supply is not right it will not burn right and cause carbon monoxide to build up.
Note: this boiler hook up was ok because the smaller gas pipe delivered above the minimum requirement of the boilers needs.

Wrong size gas pipe