¢708672;¤
708672A
O’Fallon, MO
708672A
(Replaces 7086720)
Specifi cations and illustrations subject to change
without notice and without incurring obligations.
Printed in U.S.A. (09/09)
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 orifi ce 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
