Sequence Of Operation - Trane Hyperion AM8A0A24V21CA Series Field Reference Data

AM8 Sequence of Operation
Abbreviations
• AFC = Airflow Control
• EVC = Expansion Valve Control
• EEV = Electronic Expansion Valve
• EHC = Electric Heat Control
• HHC= Hydronic Heat Control
This unit as shipped is ONLY compatible with Trane
and American Standard communicating thermo-
stats and OD units. (24VAC thermostats cannot be
used)
With the addition of a BAYCC24VK01 accessory, this
unit can be compatible with a 24VAC single or
multistage heat pump or air conditioner.
The installing and servicing technician should have an
understanding of the sequence of operation to be
able to properly setup and diagnose functions of
the air handler.
See unit, auxiliary heat, and field wiring diagrams
for additional information.
Continuous Fan
IMPORTANT: If the indoor air exceeds 60% relative
humidity or simply feels uncomfortably humid, it is
recommended that the indoor fan only be used in
the AUTO mode.
1. When a fan request is received from the ther-
mostat, the AFC sends a command to the serial
communicating blower motor to run. Airflow can be
adjusted through the thermostat
2. Humidity Control – When enabled in the thermo-
stat, this feature will disable any blower off delays
and disable continuous fan mode when the humid-
ity is above the dehumidification setpoint. This will
help prevent coil condensation from being evapo-
rated back into the air stream.
Cooling mode
1. When a request for 1st stage cooling is received,
the AFC sends a command to the serial commu-
nicating blower motor to run at 1st stage cooling
airflow. (Delay profiles from the thermostat may
change blower motor timing and actual airflow
demand)
SEQUENCE OF OPERATION FOR *AM8
2. The EVC will receive input from the two tempera-
ture sensors and start to control 1st stage super-
heat.
3. When a request for 2nd stage cooling is received,
the AFC sends a command to the serial com-
municating blower motor to run at 100 % cooling
airflow.
4. The EVC will now control superheat for 2nd stage.
5. When a request for cooling is removed, the AFC will
turn off the blower motor after any user selected
fan-off delays have expired.
NOTE: Delay profiles from the thermostat may change
blower motor timing and actual airflow demand
Heatpump (compressor only)
1. When a request for 1st stage heat is received, the
AFC sends a command to the serial communi-
cating blower motor to run at 1st stage heating
airflow.
2. Humidifier contacts close
3. The EVC will drive the EEV to the heating position
and refrigerant will flow in the reverse cycle.
4. When a request for 2nd stage mechanical heat is
received, the AFC sends a command to the serial
communicating blower motor to run at 100 % heat-
ing airflow.
5. When a request for heatpump is removed, the hu-
midifier contacts open and the AFC will turn off the
blower motor after any user selected fan-off delays
have expired.
NOTE: Delay profiles from the thermostat may change
blower motor timing and actual airflow demand
Electric Heat
1. When a request for electric heat is received, the
AFC communicates to the EHC how much de-
mand for auxiliary heat is being requested
2. The EHC determines the number of elements that
will be used for this request and sends a message
to the AFC for proper airflow. (The EHC deter-
mines the amount of heat available per stage by
either factory programming or by the kw jumper
position)
3. The AFC sends a command to the serial communi-
cating blower motor to run proper airflow and close
the blower interlock relay on the EHC.
4. Humidifier contacts close.
5. As demand from the thermostat increases, the EHC
will communicate to the AFC the required airflow
when energizing additional relays.
TAM8­4