Nordyne Downflow Direct Vent Forced Air Gas Oil Furnaces SERIES M1B User Manual
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Table 12. A/C Blower Speed Selection Chart
M1/M5*B Models and for use with Blower Kit No. 903773 1/4 Hp 3 Speed
Furance Input
Heating Speed
Setting
Cooling Speed/ Evap Coil
2 Ton
2-1/2 Ton
3 Ton
086, 090
H
L
M
H
066, 070, 077
M
L
M
H
56
L
L
M
H
M1/M5*C Models and for use with Blower Kit No. 903413 1/2 Hp 4 Speed
Furance Input
Heating
Speed
Setting
Cooling Speed/ Evap Coil
2 Ton
2-1/2 Ton & 3 Ton
3-1/2 Ton
4 Ton
077, 086, 090
ML
L
ML
MH
H
056, 066, 070
L
L
ML
MH
H
M1/M5*D Models & for use with Blower Kit No. 903890 3/4 Hp 4 Speed
Furance Input
Heating
Speed
Setting
Cooling Speed/ Evap Coil
2 Ton
2-1/2 Ton & 3 Ton
3-1/2 Ton & 4 Ton
5 Ton
077, 086, 090
ML
L
ML
MH
H
056, 066, 070
L
L
ML
MH
H
Table 11. Equivalent Orifi ce Sizes for High Altitude Installations
FURNACE
MODEL
ORIFICE SIZE AND
OUTPUT CAPACITY
ALTITUDE - FEET
SEA
LEVEL
2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
M1M/M1G
- 056
Orifi ce Size - Nat. Gas
29
29
30
30
30
30
31
31
31
32
Orifi ce 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
M1M/M1G
- 070
Orifi ce Size - Nat. Gas
24
25
26
27
27
28
28
29
29
30
Orifi ce 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
M1M - 077
Orifi ce Size - Nat. Gas
21
23
23
24
25
26
27
28
28
29
Orifi ce 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
M1G - 077
Orifi ce Size - Nat. Gas
21
23
23
24
25
26
27
28
28
29
Orifi ce 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
M1M - 090
Orifi ce Size - Nat. Gas
17
18
19
19
20
21
22
23
24
26
Orifi ce 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
M1G - 090
Orifi ce Size - Nat. Gas
17
18
19
19
20
21
22
23
24
26
Orifi ce 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
M1B - 066
Orifi ce Size - Nat. Gas
26
27
28
28
28
29
29
30
30
30
Orifi ce 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
M1B - 086
Orifi ce Size - Nat. Gas
18
19
19
20
21
22
23
24
26
27
Orifi ce 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
NOTES: 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. (Includes 4% Input Reduction for Each 1,000 Feet). These specs
do not apply to oil furnace installations. Reference Sources: ANSI Z233.1 & NFPA 54, National Fuel
Gas Code.