Bryant 345MAV User Manual
Page 41
WARNING:
Disconnect 115-v electrical power before
changing speed tap. Failure to follow this warning could
result in personal injury.
4. To change blower motor speed selections for heating mode,
remove blower motor lead from control center HEAT
terminal. (See Fig. 33.) Select desired blower motor speed
lead from 1 of the other motor leads and relocate it to HEAT
terminal. See Table 12 for lead color identification. Recon-
nect original lead on SPARE terminal.
Follow this same procedure for proper selection of COOL
speed selection.
C.
Blower Off Delay (Heat Mode)
The blower off delay has 4 adjustable settings from 90 sec to 180
sec. (See Table 13.) The blower off delay jumpers are located on
the furnace control board (See Fig. 33.) To change the blower off
delay setting, move the jumper from one set of pins on the control
board to the pins used for the desired blower off delay. Factory
blower off delay setting is 120 sec.
TABLE 13—BLOWER OFF DELAY SETUP POSITION
PINS
1 AND 2
2 AND 3
3 AND 4
4 AND 5
Time (in sec)
90
120
150
180
D.
Set Thermostat Heat Anticipator
When using a nonelectronic thermostat, the thermostat heat
anticipator must be set to match amp draw of the electrical
components in R-W circuit. Accurate amp draw readings can be
obtained at thermostat subbase terminals R and W. Fig. 49
illustrates an easy method of obtaining actual amp draw. The amp
reading should be taken after blower motor has started and furnace
is heating. Connect ammeter wires as shown in Fig. 49. The
thermostat anticipator should NOT be in the circuit while measur-
ing current. If thermostat has no subbase, the thermostat must be
disconnected from R and W wires during current measurement.
See thermostat manufacturer’s instructions for adjusting heat
anticipator and for varying heating cycle length.
For an electronic thermostat, set cycle rate for 3 cycles per hour.
VI.
CHECK SAFETY CONTROLS
This section covers the safety controls that must be checked before
the installation is complete. The flame sensor, gas valve, and
pressure switch were all checked in the Start-up prodecure section
as part of normal operation.
A.
Check Primary Limit Control
This control shuts off combustion control system and energizes
air-circulating blower motor if furnace overheats. Recommended
method of checking this limit control is to gradually block off
return air after furnace has been operating for a period of at least
5 minutes. As soon as limit control has shut off burners, return-air
opening should be unblocked to permit normal air circulation. By
using this method to check limit control, it can be established that
limit is functioning properly and operates if there is a restricted
return-air supply or motor failure. If limit control does not function
during this test, cause must be determined and corrected.
B.
Check Pressure Switch
This control proves operation of draft inducer. Check switch
operation as follows:
1. Turn off 115-v power to furnace.
2. Remove main furnace door and disconnect inducer motor
lead wires from wire harness.
TABLE 11—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
11
12
13
14
360
327
300
277
257
720
655
600
555
514
1800
1636
1500
1385
1286
50
51
52
53
54
72
71
69
68
67
144
141
138
136
133
360
355
346
340
333
15
16
17
18
19
240
225
212
200
189
480
450
424
400
379
1200
1125
1059
1000
947
55
56
57
58
59
65
64
63
62
61
131
129
126
124
122
327
321
316
310
305
20
21
22
23
24
180
171
164
157
150
360
343
327
313
300
900
857
818
783
750
60
62
64
66
68
60
58
56
54
53
120
116
112
109
106
300
290
281
273
265
25
26
27
28
29
144
138
133
129
124
288
277
267
257
248
720
692
667
643
621
70
72
74
76
78
51
50
48
47
46
103
100
97
95
92
257
250
243
237
231
30
31
32
33
34
120
116
113
109
106
240
232
225
218
212
600
581
563
545
529
80
82
84
86
88
45
44
43
42
41
90
88
86
84
82
225
220
214
209
205
35
36
37
38
39
103
100
97
95
92
206
200
195
189
185
514
500
486
474
462
90
92
94
96
98
40
39
38
38
37
80
78
76
75
74
200
196
192
188
184
40
41
42
43
44
90
88
86
84
82
180
176
172
167
164
450
439
429
419
409
100
102
104
106
108
36
35
35
34
33
72
71
69
68
67
180
178
173
170
167
45
46
47
48
49
80
78
76
75
73
160
157
153
150
147
400
391
383
375
367
110
112
116
120
124
33
32
31
30
29
65
64
62
60
58
164
161
155
150
145
TABLE 12–SPEED SELECTOR
COLOR
SPEED
FACTORY-
SHIPPED
CONNECTION
Black
High
Cool
Yellow (When Present)
Medium High
Spare
Blue
Medium Low
Heat
Red
Low
Fan
White
Common
Com
Fig. 49—Amp Draw Check with Ammeter
A80201
R
Y W G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
HOOK-AROUND
VOLT/AMMETER
EXAMPLE:
5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
= 0.5 AMPS FOR THERMOSTAT SETTING
FROM UNIT 24-VOLT
TERMINAL BLOCK
—41—