GA7T: Installation Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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Airflow Selections (ECM Furnaces)
The ECM Furnaces provide blower operation to match the capacities of
the compressor during high and low stage cooling operation. Tap
selections on the furnace control board enable the installing technician to
select the proper airflows for each stage of cooling. Below is a brief
summary of the furnace airflow configurations
1. The Y2 call for high stage cooling energizes the “Cool” tap on the
control board. The grey wire from cool tap is connected to tap 5 on
the motor. Refer to the furnace Product Data to find the
corresponding airflow. If the airflow setting for high cooling needs
to be switched from tap 5 to a different tap, jumper a connection
from the cool tap to the desired tap so that the Y2 signal is
communicated via the cool tap to the desired speed tap.
2. The Y1 call for low stage cooling energizes the “Fan” tap on the
control board. The red wire from the fan tap is connected to tap 1 on
the motor. Refer to the furnace Product Data to find the
corresponding airflow. If the airflow setting for low cooling needs
to be switched from tap 1 to a different tap, jumper a connection
from the Fan tap to the desired tap so that the Y1 signal is
communicated via the Fan tap to the desired speed tap. The Y1
setting will also govern the continuous fan airflow for the furnace.
Refer to the literature for the furnace for further details.
Airflow Selection for Variable Speed Furnaces
The variable speed furnaces provide blower operation to match the
capacities of the compressor during high and low stage cooling
operation. The furnace control board allows the installing technician to
select the proper airflows for each stage of cooling. Below is a summary
of required adjustments. See furnace installation instructions for more
details:
1. Turn SW1--5 ON for 400 CFM/ton airflow or OFF for 350
CFM/ton airflow. Factory default is OFF.
2. The A/C DIP switch setting determines airflow during high stage
cooling operation. Select the A/C DIP switch setting corresponding
to the available airflow shown in the furnace Installation
Instructions that most closely matches the required airflow shown
in the air conditioning Product Data for HIGH speed.
3. The CF DIP switch setting determines airflow during low stage
cooling operation. Select the CF DIP switch setting corresponding
to the available airflow shown in the furnace installation
instructions that most closely matches the required airflow shown
in the air conditioning Product Data for LOW speed. If a higher or
lower continuous fan speed is desired, the continuous fan speed can
be changed using the fan switch on the thermostat. Refer to the
furnace Installation Instructions for details of how to use this
feature.
Airflow Selection for FV4C Fan Coils
The FV4C provides high- and low-stage blower operation to match the
capacities of the compressor at high- and low-stage.
To select recommended airflow, refer to the FV4C Installation
Instructions. The FV4C utilizes a control board that allows the installing
technician to select proper airflows. This fan coil has an adjustable
blower-off delay factory set at 90 sec. for high- and low-stage blower
operation.
Install Electrical Accessories
Refer to the individual instructions packaged with kits or accessories
when installing.
Start-Up
Follow these steps to properly start up the system:
1. After system is evacuated, fully back seat (open) liquid and vapor
service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and caps
installed. Replace stem caps after system is opened to refrigerant
flow (back seated). Replace caps finger-tight and tighten with
wrench an additional 1/12 turn.
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature. Ensure that set point is
below indoor ambient temperature and is set low enough to
energize high stage. In order to start the system in high stage, refer
to the literature for the installed thermostat and adjust the set point
so that the differential between the room temperature and the set
temperature energizes Y2.
5. Set room thermostat to COOL and fan control to ON or AUTO
mode, as desired.
6. Operate unit for 15 minutes. Verify system refrigerant charge by
measuring the sub-cooling and comparing with the published
sub-cool on the rating plate.
System Function And Sequence Of Operation
This model utilizes a 2-stage cooling indoor thermostat. With a call for
first stage cooling, the outdoor fan and low-stage compressor are
energized. If low-stage cannot satisfy cooling demand, high-stage is
energized by the second stage of indoor thermostat. After second stage is
satisfied, the unit returns to low-stage operation until first stage is
satisfied or until second stage is required again.
When both first stage and second stage cooling are satisfied, the
compressor will shut off. Therefore, with first stage of cooling Y1 is
powered on; and with second stage of cooling Y1 and Y2 are powered
on. When a 2-stage unit is operating at low-stage, system vapor
(suction) pressure will be higher than a standard single-stage system or
high-stage operation.
CAUTION
!
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this caution may result in personal injury, equipment
damage or improper operation.
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• Do not overcharge system with refrigerant.
• Do not operate unit in a vacuum or at negative pressure.
• Compressor dome temperatures may be hot.
CAUTION
!
PERSONAL INJURY HAZARD
Failure to follow this caution may result in personal injury.
Wear safety glasses, protective clothing, and gloves when handling
refrigerant and observe the following:
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Front seating service valves are equipped with Schrader valves.