Attributes (Heat Recovery Suitability Determination) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 13.1

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Controller Configuration Tool
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The following table describes the attributes used by the Heat Recovery Suitability Determination modules.

Table 1. Heat Recovery Suitability Determination Attributes


Type 1


Default Value

Exhaust Air Temperature


Exhaust air temperature.

25 °C,

77 °F

Heat Recovery Diff


Heat recovery temperature suitability differential. Once heat recovery is suitable, the difference between Exhaust Air Temperature and OA Temperature must decrease this much below the setpoint to make heat recovery unsuitable.

1 °C,

2 °F

Heat Recovery isAllowed


Contains a network input that can be used to make heat recovery suitable or not. True means heat recovery may be suitable and False means not suitable.


HR-AVAILABLE (Heat Recovery Suitability)

G, V

Used to determine whether the heat recovery is used for cooling control or heating control, or if the heat recovery is unsuitable for either control.

Set Name: AHU HR Suit

HRT-SP (Heat Recovery Setpoint)


Contains the heat recovery temperature suitability setpoint. If the OA Temperature minus the Exhaust Air Temperature is greater than the Setpoint, Heat Recovery is suitable for cooling. If the Exhaust Air Temperature minus the OA Temperature is greater than the Setpoint, Heat Recovery is suitable for heating; otherwise, heat recovery is not suitable.

6 °C,

11 °F

Low Limit Process Variable


Contains the low limit process variable which may be the glycol temperature in a glycol loop or the exhaust air leaving air temperature for an enthalpy wheel. The low limit process variable must be reliable for heat recovery to be suitable.

7 °C,

45 °F

OA Temperature


Contains the outdoor air temperature. If the temperature difference between the exhaust air temperature and the outdoor air temperature is large enough, heat recovery may be suitable.

25 °C,

77 °F

1 C - Configuration Mode Only, G - Default Element (Generated State, if applicable), SC - Simulation and Commissioning Modes Only, V - Calculated Value (Outputs)