Equivalent Orifice Sizes At High Altitudes - Nordyne M1GH 056 Installation Instructions And Owner's Manuals

21. Equivalent Orifice Sizes at High Altitudes

(Includes 4% Input Reduction for Each 1,000 Feet)
FURNACE ORIFICE SIZE AND
MODEL OUTPUT CAPACITY
ORIFICE SIZE - NAT. GAS
M1M/G 056 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1M/G 070 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1M 077 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1G 077 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1M 090 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1G 090 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1B 066 ORIFICE SIZE - LP
OUTPUT- MBTUH
ORIFICE SIZE - NAT. GAS
M1B 086 ORIFICE SIZE - LP
OUTPUT- MBTUH
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
SEA LEVEL 2000 3000
29 29 30
45 46 47
45.4 41.8 40.1
24 25 26
42 42 43
56.7 52.3 50.2
21 23 23
40 41 42
61.7 56.9 54.6
21 23 23
40 41 42
59.9 55.2 53.0
17 18 19
36 37 38
71.7 66.1 63.5
17 18 19
36 37 38
69.7 64.2 61.7
26 27 28
43 44 44
52.6 48.5 46.6
18 19 19
37 38 39
68.2 62.9 60.3
Table 11. High Altitude
ALTITUDE - FEET
4000 5000 6000 7000
30 30 30 31
47 47 48 48
38.5 37.0 35.5 34.1
27 27 28 28
43 43 44 44
48.2 46.2 44.4 42.6
24 25 26 27
42 42 43 43
52.4 50.3 48.3 46.4
24 25 26 27
42 42 43 43
50.9 48.9 46.9 45.0
19 20 21 22
38 39 40 41
60.9 58.5 56.1 53.9
19 20 21 22
38 39 40 41
59.2 56.8 54.6 52.4
28 28 29 29
44 45 45 46
44.7 42.9 41.2 39.6
20 21 22 23
39 40 41 42
57.9 55.6 53.4 51.2
8000 9000 10000
31 31 32
49 49 50
32.7 31.4 30.2
29 29 30
45 46 47
40.9 39.3 37.7
28 28 29
44 44 45
44.5 42.7 41.0
28 28 29
44 44 45
43.2 41.5 39.8
23 24 26
41 42 43
51.7 49.7 47.7
23 24 26
41 42 43
50.3 48.3 46.3
30 30 30
47 47 48
38.0 36.5 35.0
24 26 27
42 43 43
49.2 47.2 45.3
27