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3.3.11 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.
Orifice Chart for High Altitude Installations
Altitude NATURAL
GAS
Orifice Size
PROPANE GAS
Orifice Size
0 – 4,500 ft (0 – 1372 m)
36
52
4,500 – 6,500 ft (1372 – 1981 m)
37
53
6,500 – 8,000 ft (1981 – 2438 m)
38
1/16"
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