Application

Room Segment Functions
Device Control Functions HVAC
63
Siemens Industry, Inc.
Application Note
A6V11692053
Smart Infrastructure – Building Products
2019-04-01
Electric heating coil, modulating output (HclEl11)
Application templates: 14069, 14169
This application function modulates an electric heating coil. The main output is an
analog output that is configurable for power modulation (SCR) or pulse width
modulation.
Main features:
● Analog control of electric heating coil, configurable for power modulation (SCR)
or pulse width modulation
● Heating available status
● Over-temperature detection with high temperature cut-out switch
● Air flow interlocks
Function
The heating coil heating request (HclHReq) is received and processed into the
output signal for heating coil electric position (HclElPos).
Analog control of electric heating coil: In response to heating demand, the heating
coil electric position (HclElPos) modulates to control the room temperature at
setpoint. It can also be 2-positioned in response to external trigger(s) for special
modes such as warm-up or cool down, or safety conditions.
WARNING
Electric heat coils require safety limit thermostat
Improper installation of electric heating coils can result in fire and cause
destruction of life and property.
● Install a high temperature cut-out switch on all electric heating elements.
● Ensure that all wiring and installation conform to applicable safety codes and
regulations.
The electric heating coil control logic is configured for heating coil over-
temperature detection input (HclOvrTDet) from a high temperature cut-out switch.
Parameter EnOvrTDetIn must be set to 1:Yes for the cut-out switch to function.
When the switch activates, the coil is commanded off at equipment protection
priority and a signal is sent to the source of airflow to hold / maintain airflow. A
timer prevents the source of airflow from stopping until after the timer expires.
Parameter EnOvrTDetIn must be set to 1:Yes for the cut-out switch to function
(see Configuration).
Airflow state (AirFlSta)
AirFlSta is a Boolean interlock signal (from fan) that must be True before the
electric heating coil is allowed to activate. For electric heating coils, AirFlSta is hard
coded and not adjustable. (Note, AirFlSta is an internal signal, not a BACnet object.)
Electric power usage
The nominal electric power usage of the electric heating coil is provided for energy
monitoring and coordination with other devices. The following equation calculates
the coil's electric power usage when on (HclElPos > 0%):
HclElPwr = HclElPos * NomElPwr (zero power is used when coil is off)