Continuous Fan Operation - Bryant Legacy 677C**C Series Installation Instructions Manual

fan speed and place desired speed tap wire on "HIGH" on
the interface board.
4. Refer to airflow tables (Table 8 or 9) to determine allowable
speeds for the dehumidification cooling fan speed. In Table
8 or 9, speeds that are not allowed for dehumidification
cooling are shaded.
5. Remove the vinyl cap off of the desired speed tap wire
(Refer to Table 6 for color coding) for the dehumidification
cooling fan speed and place desired speed tap wire on the
"LOW" connection on the interface board (IFB). Verify
that static pressure is in the acceptable range for the speed
tap to be used for dehumidification cooling.
6. Use any spare vinyl plugs to cap any unused speed tap
wires.
NOTE: For heat pump operation, the recommended airflow is 350
to 450 CFM for each 12,000 Btuh of rated cooling capacity.
Continuous Fan Speed Set- - up (Single Phase Models):
To change continuous fan speed:
1. Remove existing speed tap wire from the "FAN" terminal
on the IGC.
2. Connect the desired speed tap wire on the "FAN" terminal
on the IGC board.
Continuous Fan Operation (3- - Phase Models)
When the DEHUM feature is not used, the continuous fan speed
will be the same as cooling fan speed. When the DEHUM feature
is used, the continuous fan will operate on IFB "LOW" speed
when the DH control lead is not energized, or IFB "HIGH" speed
when the DH lead is energized (see Fig. 14).
Table 6 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange = Med---High Speed
Red = Med Speed
Pink = Med---Low Speed
Blue = Low Speed
DH DH
DH DH
Shunt in no
dehumidification
position
Fig. 13 - - Single Phase IGC Board
DH DH
DH DH
Shunt in
dehumidification
position
A14399
GAS
HEAT
QC6
K2
RL3 C8
RI0
C9
C4
OILL C2 D6 D4
A7
R9
D5 D3
C7
R3 R5 R6
R2
QCB
JW7
Y
Y R U
SSTZ-8
Fig. 14 - - Interface Fan Board (IFB)
Step 5 — Defrost Control
Defrost Control
The defrost control is used in all Puron (R- -410A) heat pump
models. Its features include selectable defrost intervals of 30, 60,
90 minutes, and standard defrost speed up capability. This section
describes the sequence of operation and trouble shooting methods
for this control.
Defrost Sequence
The defrost control is a time/temperature control that has field
selectable settings of 30, 60, and 90 minutes. These represent the
amount of time that must pass after closure of the defrost
thermostat before the defrost sequence begins.
The defrost thermostat senses coil temperature throughout the
heating cycle. When the coil temperature reaches the defrost
thermostat setting, it will close, which energizes the DFT terminal
and begins the defrost timing sequence. When the DTF has been
energized for the selected time, the defrost cycle begins, and the
control shifts the reversing valve into cooling position, and turns
the outdoor fan off. This shifts hot gas flow into the outdoor coil
which melts the frost from the coil. The defrost cycle is terminated
when defrost thermostat opens, or automatically after 10 minutes.
19
HIGH LOW COM
QC7 QC4 QC3
K1
DCR QCR
C
R1L Q1
D2
QC1
JM6
Q3
RI2
RI DL
JM5
G1
G2
AB A15
F1
C0
U1
R4 RL4
C3
JW3
P2
JW2
JW4
C 24VAC
JW1
P1
W2 Y2/ Y1/
DH G C R
Y
A09058