Primary States (Heat Recovery Suitability Determination) - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 15.0

Controller Tool Help
Product
Controls > Control Tools > Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
15.0
Revision date
2022-11-18

The Heat Recovery Suitability output is set to Cool if heat recovery is allowed, the temperature inputs are reliable, and Clg HR is True. The Clg HR tells the command hierarchy if the exhaust air is cold enough with respect to the outside air temperature to make cooling energy recovery suitable. The exhaust air temperature must be below the outdoor air temperature by the heat recovery setpoint amount before the CLG HR is set to True.

The Heat Recovery Suitability output is set to Heat if heat recovery is allowed, the temperature inputs are reliable, and Htg HR is True. The Htg HR tells the command hierarchy if the exhaust air is warm enough with respect to the outside air temperature to make heating energy recovery suitable. The exhaust air temperature must be above the outdoor air temperature by the heat recovery setpoint amount before the Htg HR is set to True.

The Heat Recovery Suitability output is set to None if heat recovery is allowed and is False, any temperature input is not reliable, or both Clg HR and Htg HR are False.

Table 1. Heat Recovery Suitability Determination Command Hierarchy

Heat Recovery IsAllowed

EA-T Reliable

OA-T Reliable

LL-T Reliable

Clg HR

Htg HR

Heat Recovery Suitability

False

*

*

*

*

*

None

True

False

*

*

*

*

None

True

False

*

*

*

None

True

False

*

*

None

True

False

False

None

True

True

None

True

False

Cool

False

True

Heat