9 SYSTEM PERFORMANCE MICROPROCESSOR CONTROLS
This section describes in detail how the Mini-Mate2 responds to operator inputs and room conditions.
9.1 Temperature Control
9.1.1 Cooling/Heating Required
The temperature control program for the microprocessor is based on a calculated percentage
requirement for cooling/heating.
9.1.2 Cooling Operation (Compressorized Direct Expansion and Chilled Water)
Cooling is ACTIVATED when the temperature control calculates a requirement for cooling of 100%. It is
DEACTIVATED when the cooling requirement drops below 50%. Hot gas bypass is energized on DX units
when a call for cooling occurs unless there is also a call for dehumidification.
Situation Hot Gas Bypass
Cooling only ON
Dehumidification only OFF
Cooling with Dehumidification OFF
Table 9.1 Cooling and
dehumidification load response of
hot gas bypass
9.1.3 Heating Operation
Electric Heat or Hot Water
The reheat stage is ACTIVATED when the temperature control calculates a requirement of 100%.
Conversely, the reheat is DEACTIVATED when the heat requirement is 50% less than the activation point.
SCR Electric Reheat
The SCR (Silicon Controlled Rectifier) controller proportionally controls the stainless steel reheat feature
to maintain the selected room temperature. The rapid cycling made possible by the SCR controller
provides precise temperature control, while the constant element temperature improves heater life.
During operation of the SCR control, THE COMPRESSOR OPERATES CONTINUOUSLY. The heaters are
modulated to provide temperature control. The display status will show when the unit is cooling and
heating. The control will automatically lock the compressor cooling to “ON” position, except when the
temperature falls below the low temperature alarm set point. Cooling will then be disabled until the room
temperature reaches the temperature set point.
Vertiv | Liebert Mini-Mate2—5 ton User Manual| 69
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