SET TEMPERATURE RISE
UNIT DAMAGE HAZARD
Failure to follow this caution may result in overheating the
heat exchangers or condensing flue gases in heat exchanger
areas not designed for condensate.
Temperature rise must be within limits specified on furnace
rating plate. Recommended operation is at midpoint of rise
range or slightly above.
Place SW-1 in ON position. Jumper R to W/W1 and W2 to check
high-gas-heat temperature rise. To check low-gas-heat temperature
rise, remove jumper to W2. Determine air temperature rise for both
high and low gas heat. Do not exceed temperature rise ranges
specified on unit rating plate for high and low gas heat.
This furnace must operate within the temperature rise ranges
specified on the furnace rating plate. Determine the air temperature
as follows:
a. Place duct thermometers in return and supply ducts as close
to furnace as possible. Be sure thermometers do not ’see’
heat exchangers so that radiant heat does not affect ther-
mometer readings. This is particularly important with
straight run ducts.
b. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine tem-
perature rise.
If the temperature rise is outside this range, check the following:
a. Gas input for low- and high gas heat operation.
b. Derate for altitude if applicable.
c. Return and supply ducts for excessive restrictions causing
static pressures greater than 0.50-in. wc.
d. Adjust temperature rise by adjusting blower speed. In-
crease blower speed to reduce temperature rise. Decrease
blower speed to increase temperature rise.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect 115-v electrical power before changing speed tap.
For high-heat, the following connections can be made at HI HEAT
on control:
a. Med-high (Yellow)
b. Med (Orange) -Available only on 5-speed motors. Factory
setting for these motors.
c. Med-Low (Blue) - Do NOT use for HI GAS-HEAT on
80K & 120K Btuh input models. Factory setting for
4-speed motors.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in damage to the heat
exchangers due to over temperature or condensate corrosion.
1. NEVER connect Low Speed (Red) wire to
″
HI HEAT
″
.
2. Do NOT connect Medium Low Speed (Blue) wire to
″
HI
-HEAT
″
on 80,000 Btuh and 120,000 Btuh input model
sizes.
Table 15—Altitude Derate Multiplier for U.S.A.
ALTITUDE
(FT)
PERCENT
OF DERATE
DERATE MULTIPLIER
FACTOR FOR U.S.A.*
0–2000
0
1.00
2001–3000
4–6
0.95
3001–4000
6–8
0.93
4001–5000
8–10
0.91
5001–6000
10–12
0.89
6001–7000
12–14
0.87
7001–8000
14–16
0.85
8001–9000
16–18
0.83
9001–10,000
18–20
0.81
* Derate multiplier factor is based on midpoint altitude for altitude range.
Table 16—Gas Rate (CU FT/HR)
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
1
Cu Ft
2
Cu Ft
5
Cu Ft
1
Cu Ft
2
Cu Ft
5
Cu Ft
10
360
720
1800
50
72
144
360
11
327
655
1636
51
71
141
355
12
300
600
1500
52
69
138
346
13
277
555
1385
53
68
136
340
14
257
514
1286
54
67
133
333
15
240
480
1200
55
65
131
327
16
225
450
1125
56
64
129
321
17
212
424
1059
57
63
126
316
18
200
400
1000
58
62
124
310
19
189
379
947
59
61
122
305
20
180
360
900
60
60
120
300
21
171
343
857
62
58
116
290
22
164
327
818
64
56
112
281
23
157
313
783
66
54
109
273
24
150
300
750
68
53
106
265
25
144
288
720
70
51
103
257
26
138
277
692
72
50
100
250
27
133
267
667
74
48
97
243
28
129
257
643
76
47
95
237
29
124
248
621
78
46
92
231
30
120
240
600
80
45
90
225
31
116
232
581
82
44
88
220
32
113
225
563
84
43
86
214
33
109
218
545
86
42
84
209
34
106
212
529
88
41
82
205
35
103
206
514
90
40
80
200
36
100
200
500
92
39
78
196
37
97
195
486
94
38
76
192
38
95
189
474
96
38
75
188
39
92
185
462
98
37
74
184
40
90
180
450
100
36
72
180
41
88
176
439
102
35
71
178
42
86
172
429
104
35
69
173
43
84
167
419
106
34
68
170
44
82
164
409
108
33
67
167
45
80
160
400
110
33
65
164
46
78
157
391
112
32
64
161
47
76
153
383
116
31
62
155
48
75
150
375
120
30
60
150
49
73
147
367
124
29
58
145
56
