Goodman GMVM Service Instructions Manual page 52

OPERATION
Temperature Rise Measurement
C B S
IRCULATOR LOWER PEEDS
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK
OFF
TURN 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.
heating blower speed is shipped set at "B", and the cooling blower
speed is set at "D". These blower speeds should be adjusted by
the installer to match the installation requirements so as to pro-
vide the correct heating temperature rise and correct cooling CFM.
Use the dual 7-segment LED display adjacent to the DIP switches
to obtain the approximate airflow quantity. The airflow quantity is
displayed as a number on the display, rounded to the nearest
100 CFM. The display alternates airflow delivery indication and
the operating mode indication.
Example: The airflow being delivered is 1225 CFM. The display
indicates 12. If the airflow being delivered is 1275, the display
indicates 13.
1. Determine the tonnage of the cooling system installed
with the furnace. If the cooling capacity is in BTU/hr di-
vide it by 12,000 to convert capacity to TONs.
Example: Cooling Capacity of 30,000 BTU/hr.
30,000/12,000 = 2.5 Tons
52
SUPPLY
AIR
RETURN
AIR
WARNING
2. Determine the proper air flow for the cooling system.
Most cooling systems are designed to work with air
flows between 350 and 450 CFM per ton. Most manu-
facturers recommend an air flow of about 400 CFM per
ton.
Example: 2.5 tons X 400 CFM per ton = 1000 CFM
The cooling system manufacturer's instructions must be checked
for required air flow. Any electronic air cleaners or other devices
may require specific air flows, consult installation instructions of
those devices for requirements.
3. Knowing the furnace model, locate the high stage cool-
ing air flow charts in the Specification Sheet applicable
to your model. Look up the cooling air flow determined
in step 2 and find the required cooling speed and ad-
justment setting.
Example: A *MVM960603BX furnace installed with a
2.5 ton air conditioning system. The air flow needed is
1000 CFM. Looking at the cooling speed chart for
*MVM960603BX, find the air flow closest to 1000 CFM.
A cooling airflow of 1000 CFM can be attained by se-
lecting the cooling speed "C" and the adjustment to
"normal".
4. Continuous fan speed is selectable at 25%, 50%, 75%
or 100% of the furnace's maximum airflow capability.
Example: If the furnace's maximum airflow capability
is 2000 CFM, the continuous fan speed will be 0.25 x
,
2000 or 500 CFM.
.
5. Locate the blower speed selection DIP switches on the
integrated control module. Select the desired "cooling"
speed tap by positioning switches 1 and 2 appropri-
The ately. Select the desired "adjust" tap by positioning
switches 9 and 10 appropriately. Refer to the DIP
switch chart for switch positions and their correspond-
ing taps. Verify CFM by noting the number displayed
on the dual 7-segment LED display.
6. The multi-speed circulator blower also offers several
custom ON/OFF ramping profiles. These profiles may
be used to enhance cooling performance and increase
comfort level. The ramping profiles are selected using
DIP switches 7 and 8. Refer to the following figure for
switch positions and their corresponding taps. Refer to
the bullet points below for a description of each ramp-
ing profile. Verify CFM by noting the number displayed
on the dual 7-segment LED display.