21. EQUIVALENT ORIFICE SIZES AT HIGH ALTITUDES
(Includes 4% Input Reduction for Each 1,000 Feet)
FURNACE | ORIFICE SIZE AND |
|
|
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| ALTITUDE - FEET |
|
|
| ||
MODEL | OUTPUT CAPACITY | SEA LEVEL | 2000 | 3000 | 4000 | 5000 | 6000 | 7000 | 8000 | 9000 | 10000 |
| ORIFICE SIZE - NAT. GAS | 29 | 29 | 30 | 30 | 30 | 30 | 31 | 31 | 31 | 32 |
M1M/G 056 | ORIFICE SIZE - LP | 45 | 46 | 47 | 47 | 47 | 48 | 48 | 49 | 49 | 50 |
| OUTPUT- MBTUH | 45.4 | 41.8 | 40.1 | 38.5 | 37.0 | 35.5 | 34.1 | 32.7 | 31.4 | 30.2 |
| ORIFICE SIZE - NAT. GAS | 24 | 25 | 26 | 27 | 27 | 28 | 28 | 29 | 29 | 30 |
M1M/G 070 | ORIFICE SIZE - LP | 42 | 42 | 43 | 43 | 43 | 44 | 44 | 45 | 46 | 47 |
| OUTPUT- MBTUH | 56.7 | 52.3 | 50.2 | 48.2 | 46.2 | 44.4 | 42.6 | 40.9 | 39.3 | 37.7 |
| ORIFICE SIZE - NAT. GAS | 21 | 23 | 23 | 24 | 25 | 26 | 27 | 28 | 28 | 29 |
M1M 077 | ORIFICE SIZE - LP | 40 | 41 | 42 | 42 | 42 | 43 | 43 | 44 | 44 | 45 |
| OUTPUT- MBTUH | 61.7 | 56.9 | 54.6 | 52.4 | 50.3 | 48.3 | 46.4 | 44.5 | 42.7 | 41.0 |
| ORIFICE SIZE - NAT. GAS | 21 | 23 | 23 | 24 | 25 | 26 | 27 | 28 | 28 | 29 |
M1G 077 | ORIFICE SIZE - LP | 40 | 41 | 42 | 42 | 42 | 43 | 43 | 44 | 44 | 45 |
| OUTPUT- MBTUH | 59.9 | 55.2 | 53.0 | 50.9 | 48.9 | 46.9 | 45.0 | 43.2 | 41.5 | 39.8 |
| ORIFICE SIZE - NAT. GAS | 17 | 18 | 19 | 19 | 20 | 21 | 22 | 23 | 24 | 26 |
M1M 090 | ORIFICE SIZE - LP | 36 | 37 | 38 | 38 | 39 | 40 | 41 | 41 | 42 | 43 |
| OUTPUT- MBTUH | 71.7 | 66.1 | 63.5 | 60.9 | 58.5 | 56.1 | 53.9 | 51.7 | 49.7 | 47.7 |
| ORIFICE SIZE - NAT. GAS | 17 | 18 | 19 | 19 | 20 | 21 | 22 | 23 | 24 | 26 |
M1G 090 | ORIFICE SIZE - LP | 36 | 37 | 38 | 38 | 39 | 40 | 41 | 41 | 42 | 43 |
| OUTPUT- MBTUH | 69.7 | 64.2 | 61.7 | 59.2 | 56.8 | 54.6 | 52.4 | 50.3 | 48.3 | 46.3 |
| ORIFICE SIZE - NAT. GAS | 26 | 27 | 28 | 28 | 28 | 29 | 29 | 30 | 30 | 30 |
M1B 066 | ORIFICE SIZE - LP | 43 | 44 | 44 | 44 | 45 | 45 | 46 | 47 | 47 | 48 |
| OUTPUT- MBTUH | 52.6 | 48.5 | 46.6 | 44.7 | 42.9 | 41.2 | 39.6 | 38.0 | 36.5 | 35.0 |
| ORIFICE SIZE - NAT. GAS | 18 | 19 | 19 | 20 | 21 | 22 | 23 | 24 | 26 | 27 |
M1B 086 | ORIFICE SIZE - LP | 37 | 38 | 39 | 39 | 40 | 41 | 42 | 42 | 43 | 43 |
| OUTPUT- MBTUH | 68.2 | 62.9 | 60.3 | 57.9 | 55.6 | 53.4 | 51.2 | 49.2 | 47.2 | 45.3 |
Table 12. High Altitude
Reference Sources: ANSI Z233.1 & NFPA 54, National Fuel Gas Code.
For Canadian high altitude (2,000 - 4,500'), reduce gas manifold pressure to 3.0” W.C. for
natural gas and 9” W.C. for LP gas.
NOTE: Do not attempt to change the size of an orifice by drilling it out. To do so will void the manufacturer’s warranty
INSTALLER: Please leave these installation instructions with the homeowner.
¢708074/¤
O’Fallon, MO
708074E
708074E (Replaces 708074D)
Specifications and illustrations subject to change without notice and without incurring obligations.
Printed in U.S.A. (04/06)