14
Marvair Wall Mount Heat Pump I&O Manual
06/2023 Rev.7
Configuration Menu Details
1. AC/HP Select:
This setting allows the PCB to be configured for AC (air-conditioner) or HP (heat-
pump). The system type is configured at the factory during production testing for the appropriate
system type. The default system type is AC.
2. IBM Select:
This setting allows the IBM (Indoor Blower) control signal to be configured for
PWM or 0-10vdc control. The default control output signal is PWM.
3. Fan Purge:
This setting allows the delay off time of the indoor blower once the call for the indoor
blower has been removed. The selections are N (no delay) or 10-90 seconds. After the default time
of 90 seconds the indoor blower will shut off. Selecting the N (no delay) will allow the Indoor
blower to shut off immediately after any request has been removed.
4. IBM Y1 Set:
This is an independent setting for the speed at which the Indoor blower will operate
upon a request for Y1 (1st stage cooling) via Digital Input or Modbus. The default setting for
the IBM Y1 Set is 80% of maximum speed. The speed may be adjusted from 40-100% in 1%
increments to meet desired airflow requirements. Note: Adjusting the speed too low will result
in coil freezing.
5. IBM Y2 Set:
This is an independent setting for the speed at which the Indoor blower will operate
upon a request for Y2 (2nd stage cooling) via Digital Input or Modbus. The default setting for
the IBM Y1 Set is 100% of maximum speed. The speed may be adjusted from 40-100% in 1%
increments to meet desired airflow requirements.
Note:
Adjusting the speed too low will result in coil freezing, low-pressure or high-pressure lockout.
6. OFM Select:
This setting allows the IBM (Indoor Blower) control signal to be configured for
PWM or 0-10vdc control. The default control output signal is PWM.
7. OFM Set:
This is an independent setting for the max speed at which the Outdoor fan will operate.
The default setting for the OFM Set is 80% of maximum speed. The speed may be adjusted from
65-100% in 1% increments to meet desired airflow requirements.
Note:
Adjusting the speed too low will result in coil freezing, low-pressure or high-pressure lockout.
8. Defrost Timer:
The defrost timer only applies to Heat-pump systems (when setting 1 is set to
HP). This is the accumulation timer used to monitor for heat-pump defrost control. The selections
for defrost timing is 30, 60 and 90 minutes. The defrost timer accumulates the compressor runtime
in the heat-pump mode and monitors the defrost sensor for freezing conditions to initiate a defrost
cycle at the selected defrost timing interval. The default defrost time is 30 minutes.
9. EHDD Set:
The Electric heat during defrost setting allows the electric heat to operate when a
defrost cycle is being performed in heat-pump mode. The selections for the EHDD Set are Y (yes)
or N (no). When set to N (no) the electric heat will not operate automatically during a defrost
cycle in heat-pump mode. When the EHDD Set is set to Y (yes, Default) the electric heat will
operate upon each defrost cycle in the heat-pump mode.
Note:
EHDD and SCKT cannot both be set to the Y (yes) selection at the same time. SCKT takes
priority over EHDD.
10. SCKT Set:
The SCKT setting is used to prevent simultaneous operation of the electric heat and
compressor. The selections for the SCKT Set are Y (yes) or N (no). When set to N (no, Default)
the electric heat will be allowed to operate with the compressor in heat-pump mode upon a call
