Table of Contents
Advertisement
higher than proper liquid line temperature, or remove
refrigerant if actual temperature is more than 2F (1.1C)
lower than required liquid line temperature.
NOTE:
If the problem causing the inaccurate readings is a
refrigerant leak, refer to the Check for Refrigerant Leaks section.
Indoor Airflow and Airflow Adjustments
CAUTION
!
UNIT OPERATION HAZARD
Failure to follow this caution may result in unit damage.
For cooling operation, the recommended airflow is 350 to
450 cfm for each 12,000 Btuh of rated cooling capacity. For
heating operation, the airflow must produce a temperature
rise that falls within the range stamped on the unit rating
plate.
NOTE:
Be sure that all supply- -and return- -air grilles are open,
free from obstructions, and adjusted properly.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury or death.
Before making any indoor wiring adjustments, shut off gas
supply. Then disconnect electrical power to the unit and
install lockout tag before changing blower speed.
This unit has independent fan speeds for gas heating and cooling
modes. Single phase units also have a dedicated continuous fan
speed All models (1 phase and 3 phase), have a field- -selectable
capability to run two different cooling speeds: A normal cooling
fan speed (350- -450 CFM/Ton) and an enhanced dehumidification
fan speed (As low as 320 CFM/Ton) for use with either a
dehumidistat or a thermostat that supports dehumidification.
This unit is factory- -set for use with a single cooling fan speed. For
single phase models, the cooling speed is marked "COOL" on the
IGC (See Fig. 13). For 3- -phase models, the cooling speed is
marked "LOW" on the interface board (IFB) (See Fig. 14). The
factory- -shipped settings are noted in Tables 7 and 8. There are up
to 3 additional speed tap wires available for use in either gas
heating mode, cooling mode, or continuous fan mode (For color
coding on the indoor fan motor leads, see Table 6). For single
phase models, one of the additional speed tap wires is connected to
the continuous fan, with the other 2 wires shipped loose in the
control box near the IGC. For three phase models, the additional 3
speed tap wires are shipped loose with vinyl caps and are located in
the control box near the interface fan board (IFB) (See Fig. 14).
Gas Heating Fan Speed Set- - up (Single Phase Models):
To change the gas heating speed:
1. Remove existing speed tap wire from the "HEAT" terminal
on the IGC.
2. Connect the desired speed tap wire on the "HEAT" terminal
on the IGC board. Make sure that the speed chosen delivers
temperature rise within the rise range listed on the unit.
Gas Heating Fan Speed Set-up (3- - Phase Models)
To change the gas heating speed:
1. Remove the vinyl cap off of the desired speed tap wire
(Refer to Table 6 for color coding). Table 8 and 9 show the
temperature rise associated with each fan speed for a given
static pressure. Make sure that the speed chosen delivers a
temperature rise within the rise range listed on the unit
rating plate.
18
2. Remove the current speed tap wire from the "GAS HEAT"
terminal on the interface fan board (IFB) (Fig. 14) and place
vinyl cap over the connector on the wire.
3. Connect the desired speed tap wire to the "GAS HEAT"
terminal on the interface fan board (IFB).
Cooling Fan Speed Set- - up (Dehumidification feature
not used) (Single Phase Models):
To change cooling speed:
1. Remove existing speed tap wire from the "COOL" terminal
on the IGC board. Add the wet coil pressure drop in Table
10 to the system static to determine the correct cooling
airflow speed in Table 7 that will deliver the nominal
cooling airflow listed in Table 1 for each size.
2. Connect the desired speed tap wire on the "COOL" terminal
on the IGC board.
Single Cooling Fan Speed Set-up (Dehumidification
feature not used) (3- - Phase Models)
To change cooling speed:
1. Remove the vinyl cap off of the desired speed tap wire
(Refer to Table 6 for color coding). Add the wet coil
pressure drop in Table 10 to the system static to determine
the correct cooling airflow speed in Table 8 or 9 that will
deliver the nominal cooling airflow as listed in Table 1 for
each size.
2. Remove the current speed tap wire from the "LOW"
terminal on the interface fan board (IFB) (Fig. 14) and place
vinyl cap over the connector on the wire.
3. Connect the desired speed tap wire to the "LOW" terminal
on the interface fan board (IFB).
Dehumidification Cooling Fan Speed Set- - up (Single
Phase Models):
IMPORTANT: Dehumidification control must open control
circuit on humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of
either a 24 VAC dehumidistat or a thermostat which includes
control of a 24 VAC dehumidistat connection. In either case, the
dehumidification control must open the control circuit on humidity
rise above the dehumidification set point.
1. Move shunt jumper on IGC board to "DH" (See Fig. 13).
2. Refer to airflow table (Table 7) to determine allowable
speeds for the dehumidification cooling fan speed. Speeds
that are not allowed are shaded in Table
3. Connect selected speed tap wire to "DHUM" terminal on
the IGC board. Verify that static pressure is in the acceptable
range for the speed tap to be used for dehumidification
cooling.
Two Cooling Fan Speeds Set-up (Dehumidification
feature used) (3- - Phase Models)
IMPORTANT: Dehumidification control must open control
circuit on humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of
either a 24 VAC dehumidistat or a thermostat which includes
control of a 24 VAC dehumidistat connection. In either case, the
dehumidification control must open the control circuit on humidity
rise above the dehumidification set point.
1. Remove fan speed tap wire from the "LOW" terminal on
the interface fan board (IFB) (Fig. 14).
2. Determine correct normal cooling fan speed for unit and
application. Add the wet coil pressure drop in Table 10 to
the system static to determine the correct cooling airflow
speed in Table 8 or 9 that will deliver the nominal cooling
airflow as listed in Table 1 for each size.
3. Remove the vinyl cap off of the desired speed tap wire
(Refer to Table 6 for color coding) for the normal cooling
Specifications are subject to change without notice.
7.
51801230403
Hide quick links:
Advertisement
Table of Contents
