Heating Control

Preheat Setpoint
Applicability	Systems with a preheat coil located in the outside air stream
Definition	The control temperature leaving the preheat coil
Units	Degrees Fahrenheit (°F)
Input Restrictions	As designed
Baseline Rules	Not applicable

Heating Supply Air Temperature
Applicability	All systems
Definition	The supply air temperature leaving the air handler when the system is in a heating mode (not the air temperature leaving the reheat coils in VAV boxes)
Units	Degrees Fahrenheit (°F)
Input Restrictions	As designed
Baseline Rules	20 °F above space temperature setpoint for systems 1-4. Same as maximum reset cooling supply air temperature for systems 5-8 and 105 °F for systems 9 and 10.

Heating Supply Air Temperature Control
Applicability	Systems with the capability to vary heating SAT
Definition	The method of controlling heating SAT. Choices are: No control – the heating coil is energized on a call for heating, but the supply air temperature is not directly controlled, but instead is dependent on the entering air temperature, the heating capacity and the airflow rate. Fixed (constant) Reset by coldest zone, temperature first Reset by outside air dry-bulb temperature Staged setpoint Scheduled setpoint
Units	Degrees Fahrenheit (°F)
Input Restrictions	As designed
Baseline Rules	Fixed (constant)

Heating Reset Schedule by OSA
Applicability	Systems that reset the heating SAT by outside dry-bulb temperature (this typically applies to dual-duct systems or to single zone systems with hydronic heating coils)
Definition	A linear reset schedule that represents the heating supply air temperature or hot deck supply air temperature (for dual duct systems) as a function of outdoor air dry-bulb temperature. This schedule is defined by the following data points (see below): The hottest heating supply air temperature The corresponding (cold) outdoor air dry-bulb threshold The coolest heating supply air temperature The corresponding (mild) outdoor air dry-bulb threshold Figure 3.7.2-2: Example of SAT heating setpoint reset based on outdoor air temperature (OAT)
Units	Data structure (°F)
Input Restrictions	As designed
Baseline Rules	Not applicable