30
Startup Procedure and Adjustment - Gas Manifold Pressure Mea-
surement and Adjustment for details. NOTE: The final manifold
pressure cannot vary by more than ± 0.3” w.c. from the specified
setting. Consult your local gas supplier if additional input rate
adjustment is required.
5. Repeat steps 2 through 4 on high stage.
6. Turn ON gas to and relight all other appliances turned off in
step 1. Be certain that all appliances are functioning properly
and that all pilot burners are operating.
TEMPERATURE RISE
Temperature rise must be within the range specified on the unit rat-
ing plate. An incorrect temperature rise may result in condensing in
or overheating of the heat exchanger. An airflow and temperature
rise table is provided in the Product Data Book applicable to your
model*. Determine and adjust temperature rise as follows:
1. Operate furnace with burners firing for approximately ten
minutes. Ensure all registers are open and all duct dampers
are in their final (fully or partially open) position.
2. Place thermometers in the return and supply ducts as close
to the furnace as possible. Thermometers must not be
influenced by radiant heat by being able to “see” the heat
exchanger.
RISE =
SUPPLY
AIR
RETURN
AIR
HEAT EXCHANGER
RADIATION "LINE OF SIGHT"
T
RETURN
T
SUPPLY
T
SUPPLY
-
T
RETURN
Temperature Rise Measurement
3. Subtract the return air temperature from the supply air
temperature to determine the air temperature rise. Allow
adequate time for thermometer readings to stabilize.
4. Adjust temperature rise by adjusting the circulator blower
speed. Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise. Refer
to Section XIV, Startup Procedure and Adjustment -Circulator
Blower Speeds for speed changing details.
GMV95453BX*
GMV95704CX*
GMV95905DX*
GMV951155DX*
GCV90704CX*
GCV90905DX*
390
520
650
780
600
800
1000
1200
550
600
650
700
790
865
935
1000
A
B
C
D
Low Stage
Cool
High Stage
Cool
Low Stage
Heat
High Stage
Heat
Tap
Model
390
520
715
930
600
800
1100
1430
840
920
1000
1080
1210
1325
1440
1555
A
B
C
D
520
715
910
1170
800
1100
1400
1800
1125
1195
1265
1335
1620
1720
1820
1920
A
B
C
D
520
715
910
1170
800
1100
1400
1800
1230
1265
1300
1335
1770
1825
1875
1925
A
B
C
D
390
520
715
930
600
800
1100
1430
830
915
1000
1085
1195
1320
1440
1565
A
B
C
D
520
715
910
1170
800
1100
1400
1800
1110
1185
1260
1335
1600
1700
1815
1925
A
B
C
D
D
OFF OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
Tap
1
3
5
OFF
OFF
OFF OFF
ON
ON
C
B
A
Cool
Selection
Switches
Adjust
Selection
Switches
Profile
Selection
Switches
Selection Dip Switches
Not
Used
Not
Used
Heat
Selection
Switches
8
OFF
OFF
OFF
ON
OFF
ON
ON ON
Pre-Run Short-Run
OFF Delay
60sec/100%
60sec/100%
60sec/100%
30sec/50%
30sec/50%
30sec/50%
7.5min/82%
7.5min/82%
___
___
___
___
A
B
C
D
Profiles
To set airflow: (1) Select model and desired hi
h
stage cooling airflow. Determine the corresponding
tap (A, B, C, or D). Set switches 1 and 2 to the
appropriate ON/OFF positions. (2) Select model
and desired low stage heating
airflow. Determine
the corresponding tap (A, B, C, or D). Set switches
7 and 8 to the appropriate ON/OFF positions.
(3) Select the airflow adjustment factor: Tap A is 1; Tap B is +10%; Tap C –10%.
Set dip switches 3 and 4 to the appropriate ON/OFF positions.
To set Comfort Mode:
Select desired Comfort Mode profile (see profiles above).
Set switches 5 and 6 to the appropriate ON/OFF positions.
Cooling Speed Tap 12
AOFFOFF
BONOFF
COFFON
D* ON ON
DIP Switch No.
(* indicates factory setting)
Adjust Taps 34
Normal* OFF OFF
+ 10% Adjust ON OFF
- 10% Adjust OFF ON
DIP Switch No.
(* indicates factory setting)
CIRCULATOR BLOWER SPEEDS
WARNING
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK, TURN
OFF POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS.
This furnace is equipped with a multi-speed circulator blower. This
blower provides ease in adjusting blower speeds. The Product Data
Book applicable to your model* provides an airflow table, showing
the relationship between airflow (CFM) and external static pressure
(E.S.P.), for the proper selection of heating and cooling speeds. The
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