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3.3.7 Altitude adjustment
All valves have been pre-set and certified for installation at elevations from 0 – 4500 feet (1 – 1372m)
above sea level.
When installing this heater at higher elevations, it is necessary to decrease the input rating by
replacing the existing burner orifice with a smaller size for installations over 4500 feet (1372m). The
appliances input should be reduced 4% for each additional 1000 feet (305m) above sea level. For
the USA, de-rate the heater from sea level according to the gas installation code.