What does a high altitude setting in a gas valve typically require?

A high altitude setting in a gas valve typically requires decreased gas flow. This is because as altitude increases, the atmospheric pressure decreases. At higher elevations, the reduced air density affects combustion processes, meaning that the amount of oxygen available for burning gas is lower.

To ensure efficient combustion and avoid a rich fuel-to-air mixture, the gas flow must be reduced. If the gas flow were left unchanged, it would lead to an excess of gas relative to the available oxygen, which could result in improper combustion, increased emissions, or even safety hazards. Therefore, adjusting the gas valve to decrease the flow at high altitudes is a necessary step to maintain safe and effective operation of gas-burning appliances.