Filter
Top Products
32
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.