Goodman Amana ComfortNet GMVC8 Service Instructions Manual page 36

PRODUCT DESIGN
CONTINUOUS FAN OPERATION
The two stage furnace control will energize ECM blower mo-
tor when the fan switch on the thermostat is turned to the
"ON" position. Continuous fan speed will be of the furnaces
maximum airflow capability. 25%, 50%, 75%, or 100% se-
lectable by DIP switch setting or communicating thermo-
stat.
Example: If the furnace's maximum airflow capability
is 2000 CFM, the continuous fan speed will be 0.30 x
2000 CFM = 600 CFM.
For the PCBKF103, PCBKF104, and PCBKF105 continu-
ous fan speeds that provide 25, 50, 75 and 100% of the
furnace's maximum airflow capability are selectable via dip
switches S5- 3, 4.
Example: If the furnace's maximum airflow capability is
2000 CFM and 25% continuous fan speed
is selected, the continuous fan speed will be
0.25 x 2000 CFM = 500 CFM.
S5
Continuous Fan
100%
CIRCULATOR BLOWER SPEED ADJUSTMENT
HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFOR CHANGING SPEED TAPS.
M
ULTIPLE POWER SOURCES MAY BE PRESENT.
SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
In general lower heating speeds will: reduce electrical con-
sumption, lower operating sound levels of the blower, and
increase the outlet air temperature delivered to the home.
The speeds available allow the blower performance to be
optimized for the particular homeowner's needs.
This furnace is equipped with a multi-speed circulator blower.
This blower provides ease in adjusting blower speeds. The
Specification Sheet applicable to your model provides an
airflow table, showing the relationship between airflow (CFM)
and external static pressure (E.S.P.), for the proper selec-
tion of heating and cooling speeds. The 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 in-
staller to match the installation requirements so as to pro-
vide the correct heating temperature rise and correct cool-
ing CFM.
Use the dual 7-segment LED display adjacent to the
dipswitches 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 indica-
tion.
36
SWITCH
3 4
25% Off Off
50% On Off
75% Off On
On On
WARNING
F
AILURE TO DO
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
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 manufacturers
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 installa-
tion 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 adjust-
ment setting.
Example: A GMVC80604B furnace installed with a
2.5 ton air conditioning system. The air flow needed is
1000 CFM. Looking at the cooling speed chart for
GMVC80604B, find the air flow closest to 1000 CFM. A
cooling airflow of 990 CFM can be attained by setting
the cooling speed to "C" and the adjustment to -10%
trim.
4. Continuous fan speeds that provide 25, 50, 75 and 100%
of the furnace's maximum airflow capability are select-
able via dip switches S5- 3, 4.
Example: If the furnace's maximum airflow capability
is 2000 CFM and 25% continuous fan speed is selected,
the continuous fan speed will be 0.25 x 2000 CFM = 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 appropriately.