Carrier RTU-MP, Integration Manual

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RTU-MP Controller 17
Power Exhaust
If an optional exhaust fan is used and controlled by the RTU-MP, it can be enabled based on damper position
or by occupancy. If configured for continuous occupied operation, it will be energized whenever the controller
is in the occupied mode and disabled when in the noccupied mode.
If configured for damper position control, it will be energized whenever the economizer exceeds the power
exhaust setpoint and disabled when the economizer drops below the setpoint by a fixed hysteresis of 10%.
Energy Recovery
The RTU-MP does not contain additional specific controls for energy recovery devices. However, most energy
recovery units are compatible with typical economizer and power exhaust inputs and outputs and can be used
with the RTU-MP. See the specific energy recovery device input & output requirements for additional
information.
Heating
The compressor outputs are controlled by the Heating Control PID Loop and Heating Stages Capacity
algorithm. They will be used to calculate the desired number of stages needed to satisfy the space by
comparing the SPT to the Occupied Heat Setpoint, the T56 slider offset when occupied, and the Unoccupied
Heat Setpoint, plus the T56 slider offset, if unoccupied.
The following conditions must be true in order for this algorithm to run:
• Indoor Fan has been ON for at least 30 seconds.
•
Cool mode is not active and the time guard between modes equals zero.
•
If occupied and SPT <(occupied heat setpoint plus T56 slider offset)
•
SPT reading is available
• If it is unoccupied and the SPT < (unoccupied heat setpoint plus T56 slider offset). The indoor fan will be
turned on by the staging algorithm.
•
OAT < High OAT lockout temperature.
If all of the above conditions are met, the heating outputs will be energized as required, otherwise they will be
de-energized.
If the SAT begins to exceed the high supply air setpoint, a ramping function will cause the Heat Stages
Capacity algorithm to decrease the number of stages until the SAT has dropped below the setpoint. There is a
fixed one minute minimum on-time and a one minute off-time for each heat output. Heat staging has a 2
minute stage-up and 30 second stage-down delay.
Heat pump operation (if the Heat Pump RTU configuration is set to
YES ) is the same as above, except for the
following:
•
There is a fixed 3 minute on and 5 minute off-time for the first heat stage output, and a 1 minute on and
1 minute off-time for the second heat stage output.
•
There is a 10 minute minimum stage-up delay if the heat demand is <= 3°F, and a 2 minute minimum
stage-up delay if heat demand is > 3°F. The stage down delay is still 30 seconds.
•
If the Compressor Safety Alarm is active, the second heat stage will come on with the first stage with no
delay.