Reznor R6GI Unit Installation Manual - Manual (Page 13)

13
NOTE: When low fire on the gas valve is energized,
the furnace operates in low fire mode at a lower blower
speed and the timer begins its delay function. If the room
thermostat is not satisfied before the timer activates, the
furnace will stage to high fire. The inducer motor and
blower will ramp to a higher speed until the thermostat
is satisfied.
Configuring the Variable Speed Blower
The variable speed blower has been designed to give
the installer maximum flexibility for optimizing system
performance, efficiency, and comfort. It is equipped with
a microprocessor-controlled variable speed motor that is
pre-programmed to deliver optimum airflow in a variety of
conditions and system configurations. Because the blower
can be configured in many ways, it is important to read
and follow all instructions carefully.
CAUTION:
To avoid personal injury or property damage,
make certain that the motor leads cannot
come into contact with any uninsulated metal
components of the unit.
Upon initial start up, the variable speed blower must be
checked so that the factory settings match the unit with the
system, climatic conditions, and other system options. With
the blower installed and configured properly, the furnace
will gradually change speed in response to changes in
system variables such as thermostat settings, duct static,
filters, etc. The variable speed blower is configured by
setting the eight dip switches for heating and cooling
operation located on the blower control board. See
Figure
13 (page 30) for dip switch location.
NOTES:
• For change in blower speed selection to take effect,
system power must be cycled off then restored after
10 seconds.
•
Special attention must be given to dip switch location
1. The blower control board provides four separate
programs, one for each specific unit tonnage, and is
designed to automatically identify the motor horsepower
installed in that specific unit. 1/2 HP motor for 2 & 3
ton models and 1 HP motor for 4 & 5 Ton models. Dip
switch #1 of the blower control board is factory set for the
specific unit tonnage where this dip switch determines
the following:
0 = OFF position = 2 Ton with 1/2 HP motor
1 = ON position = 3 Ton with 1/2 HP motor
0 = OFF position = 4 Ton with 1 HP motor
1 = ON position = 5 Ton with 1 HP motor
Selecting Cooling Airflow
Dip Switches # 5, 6, 7, & 8
The COOLING airflow is selected by setting dip switches
# 5, 6, 7, & 8 on the blower control board.
Table 12, (page
27) lists the recommended airflow values (CFM) and
switch settings for each nominal system capacity. All
airflows for other modes of operation are determined by
these basic settings. For maximum capacity, generally,
a selection near the middle or top of the CFM range for
that nominal capacity is used.
NOTES:
• The CFM values listed in
Table 13 & Table 14, (page
27) are not dependent on duct static pressure. The
motor automatically compensates (within the limits of
the motor) for changes in duct static pressure.
• If coil icing occurs, the basic cooling airflow selected
may be too low. Verify the selected setting is within the
range shown in
Table 13 and the system is properly
charged. If icing continues, raise the selected airflow
to the next higher tap.
• For maximum dehumidification and energy efficiency,
select an airflow near the middle or bottom of the CFM
range for that nominal capacity.
• The 2-stage cooling feature of the unit requires
modulating the airflow. The unit will automatically adjust
the airflow to the appropriate rate when the unit capacity
changes.
Selecting Heating Airflow
Dip Switches # 2, 3, & 4
The HEATING airflow is selected by setting dip switches
# 1, 2, 3, & 4 on the blower control board.
Table 14,
(page 27) lists the recommended airflow values (CFM)
and switch settings for each heat exchanger capacity.
All airflows are determined by these basic settings. For
most applications the factory heat setting will operate at
a nominal rise based on the furnace’s nominal efficiency
and firing input. Follow across the table row to find the
switch setting and nominal air-flow. Verify the selected
rise is within the specification shown on the furnace rating
label or
Table 12, (page 27) .
Operation
When 24VAC is present at the DEHUM terminal of the
blower control board the airflow requirements will be
reduced to 75% of the nominal airflow requirements. If
the humidity level of the conditioned space decreases
during the cycle and the humidistat opens, the airflow will
be restored to 100% of the selected value.