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820SB/821SB: Installation, Start–Up, Operating and Service and Maintenance Instructions
Unit Size
36045V14
36070V14
48070V17
48090V17
60090V21
66110V21
66135V24
*. Setting #1 is the default setting for Constant Fan
FURNACE CONTROL PROGRAMMING
AND NAVIGATION
On-Board Control Method
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury, or death.
Blower access door switch removes 115-V power to control. No
component operation can occur unless switch is closed. Caution must
be taken when manually closing this switch for service purposes.
Do not tape or permanently allow the door switch to be bypassed.
Temporarily depress the door switch with one hand while accessing the
service buttons with your other hand. Do not touch uninsulated
electrical components.
Display
iDl
Ht
CL2
CL1
Heat Pump Defrost Mode
Hpd
,
,
Continuous Fan Mode
Cfn
CF2
CF3
Secondary Unit Operating
bLr
##.#
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 11 – Default Airflow Settings
Default Airflow Settings
Heating
7
15
13
14
12
13
16
Table 12 – System Status Display Codes
Operating Mode
Notes
Idle/Standby Mode
No active demands
Heating Mode
Gas Heating active
High Cooling Mode
Cooling or Heat Pump active
Low Cooling Mode
Cooling or Heat Pump active
Gas Heating cycle active during Heat Pump Defrost cycle
Continuous Fan active
Only used when control is the secondary furnace of a twinned furnace system and primary
Blower
furnace is active
Active Status Code
See
Fig. 46
*
High Cooling
Low Cooling
23
13
23
13
25
14
25
13
23
12
21
11
22
11
This furnace model is equipped with an on-board 3-digit LCD display
with pushbutton navigation for the adjustment of operating parameters,
diagnostics, and service. The control board must be powered to use the
display and pushbuttons. Upon startup, the control will alternate
displaying the Model Program Number (PRG) and Software Version
(uEr). The control board has been programmed at the factory with a
Model Program Number specific to the furnace product number. The
correct Model Program Number is shown on the furnace rating plate.
The system's status is displayed after startup or after no control buttons
have been pressed for 60 seconds. Status code LED will also be
illuminated or blinking when displaying the system status. The codes
which indicate the current operating mode of the system as shown in
Table
12.
or Furnace Service Label for codes
28
Designated Airflow Settings
Heating
Constant Fan
(3 - 11)
(1 - 9)
(10 - 19)
(1 - 9)
(7 - 15)
(1 - 4)
(8 - 21)
(1 - 10)
(7 - 17)
(1 - 9)
(8 - 18)
(1 - 9)
( 9 - 19)
(1 - 8)
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