Equivalent orifice sizes at high altitudes, Table 12. high altitude – Nordyne Forced Air Gas and Oil Furnace M1M User Manual
Page 40
¢708672;¤
7086720
O’Fallon, MO
7086720 (Replaces 708074E)
Specifications and illustrations subject to change
without notice and without incurring obligations.
Printed in U.S.A. (12/06)
INSTALLER: Please leave
these installation instructions
with the homeowner.
21. EQUIVALENT ORIFICE SIZES AT HIGH ALTITUDES
(Includes 4% Input Reduction for Each 1,000 Feet)
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
Table 12. High Altitude
FURNACE
ORIFICE SIZE AND
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