NightPurge

The NightPurge component uses the two sets of temperature and humidity inputs to find the air supply with the least amount of heat if the Purge Enabled input is true. The Free Cooling output will be set to false if outside is greater than or equal to inside or set to true if outside equals to the Night Setpoint.

NightPurge component

Slots

The NightPurge component has the following slots:

• Status: shows the component's status;
• Unit Select: specifies the units of the temperature and humidity properties;
• Purge Enabled: Boolean data type, must be true to enable the night purge operation. Whenever false, the Free Cooling output is set to the opposite of the Free Cooling Command (or null, if the Use Null Output is set to true), and the Current Mode slot value is Disabled. The Purge Enabled is often linked to a "Not" object sourced from the Boolean Schedule output;
• Outside Temperature: input for the current outside air temperature; the input must be valid for this object to function;
• Outside Humidity: input for the current outside air humidity; the input must be valid for this object to function;
• Inside Temperature: input for the current inside air temperature; the input must be valid for this object to function;
• Inside Humidity: input for the current inside air humidity; the input must be valid for this object to function;
• Low Temperature Limit: this property is used to provide freeze protection;
• Night Setpoint: inside night temperature setpoint, at or below which the Free Cooling is not applied. Instead, the Current Mode is set to Satisfied;
• Outside Enthalpy: this is the calculated outside air enthalpy;
• Inside Enthalpy: this is the calculated inside air enthalpy;
• Free Cooling: Boolean output set to the value of the Free Cooling command when it is determined that free cooling should be used. Otherwise, the value is set to the opposite state or null (if the Used Null Output is set to true);
• Current Mode: indicates which of the following modes the component is currently in;
  • Available options: Disabled (Purge Enabled is false), Free Cooling, No Free Cooling (free cooling not available), Low temperature (Outside Temp Below Low Temperature Limit, free cooling disabled), Input error (temperature or humidity is invalid-down, fault, etc.), free cooling disabled), satisfied (inside temperature below the Night Setpoint, free cooling disabled);
• Setpoint Deadband: the Temperature Setpoint Deadband is applied when the inside temperature falls below the Night Setpoint before free cooling can be enabled; the default value is 1.0;
• Threshold Span: the difference between the inside enthalpy and the outside enthalpy must be greater than this value before free cooling will be enabled; the default value is 1.0;
• Use Enthalpy: setting this property to true will enable the use of enthalpy for determining if free cooling is available. Otherwise, it will just use outside and inside temperature to decide.