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Marvair MGA3090-3180 Wall Mount AC I&O Manual 05/2023 Rev.14
for W2 (auxiliary / emergency heat). When the SCKT Set is set to Y (yes) the electric heat will
not be allowed to operate with the compressor in the heat-pump mode. When set to Y (yes) and
upon a request for W2 (auxiliary / emergency heat) the compressor will shut off and the electric
heat will operate.
Note:
SCKT and EHDD cannot both be set to the Y (yes) selection at the same time. SCKT takes
priority over EHDD.
11. ODS Set:
The ODS Set is used to set the Outdoor Sensor temperature for Heat-pump systems.
When the system type is configured for Heat-pump (when setting 1 is set to HP), the ODS Set
allows the outdoor sensor to be used to govern when electric heat is allowed to operate. When
the outdoor temperature is below the ODS setpoint, the electric heat will be allowed to operate.
The adjustable range is 0F-70F in 1F increments with a default setpoint of 50F.
12. ECONO Select:
The ECONO Select is used to select whether the system has an economizer
system installed or not. When set to the Y (yes) selection the system will include the economizer
cooling algorithm within its sequence of operation and utilize the economizer package when
conditions are favorable for economizer cooling. When set to the N (no) selection the system will
only utilize the compressor for cooling operation. This setting is configured at the factory during
production testing for the appropriate system type.
Note:
When ECONO Set is set to Y (yes) the system must have an Enthalpy or Dry Bulb and
Supply Air sensor connected and properly selected in setting 13 in order to operate in economizer
cooling. The system will default to compressor cooling if any sensor becomes disconnected or
faulty. Changing the ECONO Select to N (no) will disable economizer operation and the economizer
function will be ignored.
13. Sensor Type:
This setting is used for selecting the type of economizer sensor used EN (Enthalpy) or
DB (Dry Bulb). The appropriate sensor must be connected and selected for economizer operation.
This setting is configured at the factory during production testing for the appropriate sensor type.
14. ECONO Set:
This setting is used to set the economizer setpoint at which the economizer is
allowed to operate for cooling. When setting 13 is set for EN (Enthalpy), the selections are A=
73F, B=70F, C=67F, D=63F and E=55F all at 50% relative humidity. The A – E selections will only
be available when setting 13 is set to EN (Enthalpy). When setting 13 is set for DB (Dry Bulb),
the selection is from 20F to 105F in 1F increments. The 20F-105F range will only be available
when setting 13 is set to DB (Dry Bulb).
15. MIN POS:
The MIN POS setting is for setting the minimum position of the economizer or
motorized damper. When set above 20 (2vdc) the damper will remain open to the selected position
at all times, hence minimum position. The adjustable range is from 20 (2vdc) to 100 (10vdc) in
1vdc increments.
16. W2 Speed:
This is an independent setting for the speed at which the Indoor blower will operate
upon a request for W2 (Electric heat) via Digital Input or Modbus. The default setting for the W2
speed is 100% of maximum speed. The speed may be adjusted from 70-100% in 1% increments
to meet desired airflow requirements.
Note:
Adjusting the speed too low will result in increased supply air temperatures in electric heat
mode.
17. Dehum Speed:
This is an independent setting for the speed at which the Indoor blower will operate
upon a request for HUM (Dehumidification) via Digital Input or Modbus. The default setting for
