Emerson MINI-MATE2 7.0SYSTEM PERFORMANCE MICROPROCESSOR CONTROLS, 7.1.1Cooling/Heating Required

System Performance Microprocessor Controls

7.0SYSTEM PERFORMANCE MICROPROCESSOR CONTROLS

This section describes in detail how the Mini-Mate2 responds to operator inputs and room conditions.

7.1Temperature Control

7.1.1Cooling/Heating Required

The temperature control program for the microprocessor is based on a calculated percentage requirement for cooling/heating.

7.1.2Cooling 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.

Table 22 Cooling and dehumidification load response of hot gas bypass

Situation	Hot Gas Bypass
Cooling only	ON
Dehumidification only	OFF
Cooling with	OFF
Dehumidification

7.1.3Heating 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.

7.2Humidity Control

7.2.1Dehumidification/Humidification Required

The humidity control is based on a calculated percentage requirement for dehumidification or humidification (i.e., the difference between the return air humidity and the humidity set point). As the return air humidity rises above the humidity set point, the percent dehumidification required increases proportionally from 0 to 100% over a humidity band equal to the humidity sensitivity setting. The converse is true for percent humidification requirement.

7.2.2Dehumidification Operation, Compressorized Direct Expansion (DX) Systems

Dehumidification with the standard configuration is accomplished by operating the compressor without the hot gas bypass active. Dehumidification will be disabled if the heating requirement exceeds 125%. It is re-enabled when the heating requirement reaches 50%.

Liebert® Mini-Mate2™ 50