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30
S
TART
-
UP
P
ROCEDURE
AND
A
DJUSTMENT
SUPPLY
AIR
RETURN
AIR
Temperature Rise Measurement
1. Operate furnace with burners firing approximately 15
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.
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 the following section for speed changing details.
CIRCULATOR B LOWER S PEED A DJUSTMENT
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECT RICAL
SHOCK
,
TURN
OFF
POWER
TO
THE
FURNACE
BEFORE
CHANGING
SP EED
TAPS
.
WARNING
This furnace is equipped with a PSC circulator blower motor.
This blower provides ease in adjusting blower speeds. Refer to
the Blower Performance Data in the back of the manual for
proper selection of heating and cooling speeds. The cooling
blower speed is shipped set on HIGH. High heat ships on
MEDIUM and low heat is shipped on MEDIUM-LO. These blower
speeds should be adjusted by the installer to match the instal-
lation requirements so as to provide the correct heating tem-
perature rise and the correct cooling CFM.
To adjust the circulator blower speed, proceed as follows:
1. Turn OFF power to the furnace.
2. Select the heating and cooling blower speeds that match
the installation requirements from the airflow table in the
Specification Sheet applicable to your model. (Please
contact your distributor or our website for the applicable
Specification Sheet referred to in this manual.)
3. Relocate desired motor leads to the circulator blower
heat and cool speed terminals on the integrated control
module. (Terminals are identified as LO HEAT, HI HEAT
and COOL (hot)) for *(M,D)H8 models and HEAT and
COOL for *(M,H,D)S8 models). If a heating speed and
the cooling speed are the same, a jumper wire must be
used between the heat and cool terminals.
4. Connect all unused blower motor leads to the “PARK”
terminals on the integrated control module. Any leads
not connected to the “PARK” terminals must be taped.
5. Turn ON power to furnace.
6. Verify proper temperature rise as outlined in Temperature
Rise section.
CIRCULATOR B LOWER F AN T IMING A DJUSTMENT
NOTE: Items in this section refer to the air circulator blower
fan in the *(M,D)H8 models, NOT to the induced draft blower.
The induced draft blower timing sequence is not adjustable.
The circulator blower fan timing is adjustable only on models
with optional “heating fan OFF delay” adjustment pins or
switches. It is NOT adjustable in any other circumstances.
As shipped, the circulator blower fan will remain on for 150
seconds after the gas valve closes. When a call for cooling
occurs, the circulator fan comes on and remains on for 45 sec-
onds after the call for cooling ends. During normal heating op-
eration, the circulator fan will come on approximately 34 sec-
onds after the gas valve opens.
O
N
O
F
F
O
N
O
F
F
1
150
SECOND
DELAY
100
SECOND
DELAY
1
Switch viewed in an upflow installation.
Adjustment Switch
SETTING F URNACE O PERATING M ODE (*DH8, *ME8, AND
*MH8 MODELS ONLY)
This furnace is designed to operate with either a single gas
input rate or with two discrete gas input rates. The Mode
DIP switch is used to select the single gas input rate or two
discrete input rates.
Setting the Mode switch to “1 STG” forces the furnace to
operate at the furnace’s highest input rate only. Operation is
as described under Sequence of Operation (Integrated
Ignition Control) – Mode DIP Switch is set to “1 STG”
position.