Reznor RCB User Manual

Form CP-MAPSIII-D21, Doc No 303070, Page 5
The makeup air control system operates the supply fan, the intake dampers, DX
cooling, and gas or electric heat to maintain a set of discharge air temperature control
setpoints.
The unit discharge air temperatures fall within the following three categories:
1. Unit supplies neutral temperature air that does not affect space
conditions.
2. Unit supplies cold temperature air to provide space cooling.
3. Unit supplies hot temperature air to provide space heating.
NOTE: Heating applies only when a unit is ordered with a gas or electric
heat section. Heating is included in all control instructions.
Thesequenceisbrokenintoveprimarystatesofoperation.
2.0 Sequence of
Operation
2.1 States of
Operation
The unit can switch between states based on the following:
• Controller Display
• th-tune Space Control Device (Option CL78)
• Building Automation Command (Option BHB7 or BHB8)
• Automatically based upon sequence of operation.
The unit state is the primary determination of individual component function.
1. Off
The unit supply fan and all associated mechanical
equipment is OFF in this state. There are no
associated sequences of operation in this state. The
unit will only switch to the OFF state when the state is
manually selected through the th-tune device (Option
CL78), unit display, or building automation network
communication point. Upon initial power, Unit OFF is
the default state.
2. Off / Alarm
The Off / Alarm state can only occur from a sequence
“failure”. The unit will switch to this state from the
heating, cooling, or auto state. The unit will stop all
mechanical operation until the “failure” condition(s)
are resolved. The unit will be OFF. Upon resolving the
failure, the unit will return to heating, cooling, or auto
state. Alarms can also be cleared by resetting power to
the unit.
3. Heat (optional)
From the th-tune device (Option CL78), controller
display, or BMS, the heat state can be selected. The
supply fan will run and the mechanical heating and
the dampers will be operated to maintain heating
sequence of operation. The unit will not automatically
switch to other states except Off / Alarm.
4. Auto
From the th-tune device (Option CL78), controller
display, or BMS, the auto state can be selected. Upon
initial selection of the auto state, the unit will be in the
auto-heating state (if equipped) whenever the outdoor
air temperature is below 65°F(18°C), otherwise the
unit will be in the auto-cooling state. The unit will
change to auto cooling/auto-heating state whenever
the temperature crosses the changeover setpoint
for more than 15 minutes or is more than 5°F(2.8°C)
beyond the changeover setpoint.
The unit mechanical function is exactly the same
in either cooling or heating state, other than the
sequence’s ability to change states. NOTE: The unit
switches between heating and cooling based upon
outside air temperature. Space temperature does not
dictate heating or cooling mode.
5. Cool
From the th-tune device (Option CL78), controller
display, or BMS, the cool state can be selected. The
unit supply fan will run and the mechanical cooling and
the dampers will be operated to maintain the cooling
sequence of operation. The unit will not automatically
switch to other states except Off / Alarm.

Reznor RCB Specifications

General

Brand	Reznor
Model	RCB
Category	Air Handlers
Language	English