Application

Room Segment Functions
Device Control Functions HVAC
61
Siemens Industry, Inc.
Application Note
A6V11692055
Smart Infrastructure – Building Products
2019-04-01
Electric Heating Coil, 2-Stage (HclEl14)
The application function Electric heating coil two stage, two binary outputs
operates a pair of electric heating coils to provide 2-stage heating. The main
outputs are two binary outputs that work together for two stage operation.
NOTE:
The Electric heating coil (2-Stage) receives the heating request signal from the
room temperature control for heating PID controller. The room temperature
heating controller (TRCtlH) is a BACnet Loop Object that supports either PID or
Stage Control.
Electric heating coil has been preloaded with staged controller sets configured.
A demand signal of 0-100% is converted to binary output using hard coded switch-
on, switch-off points.
Main features:
⚫ Binary control of two electric heating coils for 2-stage operation
⚫ Heating available status
⚫ Over-temperature detection with high temperature cut-out switch (Optional)
⚫ Airflow interlocks
Primary signal flow is summarized as follows:
Heating coil heating request (HclHReq) is received from the room and processed
into binary output signals for the dual electric heating coil stage positions
(HclEl1StPos, HclEl2StPos).
Basic function: Accept request signal from associated room controller and pass it
through a device mode logic switch;
Output the result as a command to the BACnet object that controls the device.
Binary control of two electric heating coils (HclEl1StPos / HclEl2StPos), staged
on/off, to control the room temperature at setpoint. The stages also can be
commanded in response to external trigger(s) for special modes such as warm-up
or cool down, or safety conditions.
The electric heating coil AF receives the percentage value of the heating demand
signal (HclHReq) and translates it into the number of stages that should be turned
on. No stages turned on is approximately 0%, one stage approximately 50% and two
stages approximately 100%.
NOTES:
There are NO minimum on or minimum off delay timers for turning the coils on
and off.
The default interstage delay (staged controller, switch delay) for two stage coils
turning on or off can be set as needed for room control.