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Unit Options
Building Signal Damper Control
When this option is ordered, the outdoor air (supply) and return dampers will modulate based on a 0-10V
DC signal from the Building automation system. 0V = max outside air, 10V = max return air. Direct fired
units cannot go below 20% outside air, maximum output voltage may differ.
Electric Cabinet Heater
Units can be shipped with an optional 120V electric cabinet heater powered from the MUA board. There is
a temperature sensor built onto the MUA board that will regulate when the cabinet heater activates. To
enable this option go to
Factory Settings > Unit Options > Cabinet Heater > Enable
. Temperature
readings and adjustments can be made through the HMI. Go to
User Settings > Temp Set Points >
Option Set Points > Cab Heat Set Points
.
Motorized Intake Damper
On units shipped with the optional motorized intake damper, a power transformer is supplied with the unit if
the main incoming voltage is greater than 120V. No external wiring to the damper motor is required.
Mixing Box Control Unit Options
Manual Control
- The dampers can be controlled from the HMI in the unit or from a space HMI if one is
provided to any position from 20% to 100% fresh air. This is a 0-10V setting, which is available under user
settings, 100% Outdoor Air (0 volts), 80% Return Air (equivalent voltage). This will allow to manually set
the dampers to match the building ventilation requirements. On a power failure, the return air damper will
close by spring return.
Two Position Control
- The dampers can be controlled by a two-position switch (a field-supplied
switching device) to open the fresh air to 100%. The MUA board sends out a constant voltage. The field
supplied switch will cut or allow the signal from the MUA board to the mixing box damper. On opening of
the circuit, power failure, or if the unit is shut off, the return air damper will close by spring return. If the
circuit is closed, the MUA board will allow the return air damper to open per the setpoint.
Outdoor Air %
- The dampers can be controlled from the HMI in the unit or from a space HMI if one is
provided to any position from 20% to 100% fresh air. There is an outdoor air percentage setting which is
available under user settings. This will allow the user to manually set the dampers to match the building
ventilation requirements.
• When preset OA is On, the unit will use preset values for mixing box OA% by directly associating
OA voltage to OA percentages. A calibration can be run from the service menu to store and use
real-world results rather than provided defaults.
• When preset OA is Off, the MUA board utilizes an internal algorithm to alter its 0-10V output to the
mixing box damper in order to maintain an exact outdoor air percentage. When this mixing box
option is selected, a mixing box dead-band comes into play. This setting checks the delta T
between outdoor and return air. If the difference between these two temperatures is less than or
equal to the mixing box dead-band setting, the MUA board will not alter its output to the mixing box
damper (default setting is 5 degrees). On a power failure, or if the unit is turned off, the return air
damper will close by spring return.
Analog Control
- When this is set to ON, a 0-10V input will drive the damper output to modulate linearly
between the min and max OA voltage for both occupied and unoccupied modes.
Static Pressure Control
- Damper position will modulate to maintain building pressure. Building pressure
below the setpoint will increase the amount of outdoor air supplied to increase pressure. Building pressure
above the setpoint will decrease the amount of outdoor air supplied to decrease pressure.
CO2 Control
- When the unit senses the CO2 input to be above the threshold setting, the unit will
decrease mixing box output until the CO2 falls below threshold setting.
Summary of Contents for MUA Controls
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