GCSS96 Installation Manual

35
SUPPLY
AIR
RETURN
AIR
Temperature Rise Measurement
Figure 40
CIRCULATOR BLOWER SPEEDS
This furnace is equipped with a multi-speed circulator blower.
This blower provides ease in adjusting blower speeds. The Speci-
fication 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 selection of heating and
cooling speeds.
T O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK ,
TURN OFF POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS .
WARNING
1. Determine the tonnage of the cooling system installed
with the furnace. If the cooling capacity is in BTU/hr divide
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 volume
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
3. Select the heating speed for your model from the heating
speed chart in the Specification Sheet. The selected speed
must provide a temperature rise within the rise range
listed with the particular model.
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.
3. Relocate desired motor leads to the circulator blower
heat and cool speed terminals on the integrated control
module. (Terminals are identified as HEAT and COOL).
If heating and cooling blower speeds 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 the
Temperature Rise section of Startup Procedure and
Adjustment.
In general lower heating speeds will: reduce electrical consump-
tion, lower operating sound levels of the blower, and increase the
outlet air temperature delivered to the home. The speeds avail-
able allow the blower performance to be optimized for the par-
ticular homeowner’s needs.
BLOWER HEAT OFF DELAY TIMINGS
The integrated control module on 96% models provides a select-
able heat off delay function. The heat off delay period may be
set to 100 or 150 seconds by cutting the jumper on the control
module. The delay is factory shipped at 150 seconds but may be
changed to suit the installation requirements and/or homeowner
preference.
The integrated control board on 92% models has a fixed blower
off delay of 150 seconds.
N ORMAL S EQUENCE OF O PERATION
POWER UP
The normal power up sequence is as follows:
• 115 VAC power applied to furnace.
• Integrated control module performs internal checks.
• LED will flash once at power up then remain on.
• Integrated control module monitors safety circuits
continuously.
• Furnace awaits call from thermostat.
HEATING MODE
The normal operational sequence in heating mode is as follows:
• R and W thermostat contacts open, completing the
call for heat.
• Gas valve closes, extinguishing flame.
• Induced draft blower is de-energized following a
fifteen second post purge.
• 96% models HUM terminal is de-energized.
• For 96% Models: Circulator blower continues running
for the selected heat off delay period Factory set at
150 seconds.
• EAC terminal is de-energized
For 92% Models: The blower off delay is 150 seconds
(non-adjustable).
• Furnace awaits next call from thermostat.
COOLING MODE
The normal operational sequence in cooling mode is as follows: