enteliZONE Sequence of Operations
Page 66 of 84 eZV-440 Application Guide
Edition 2.6
l When there is a demand for duct heating. The fan will run whenever a stage of binary duct
heat is called or when a modulating stage of duct heat reaches 25% demand. Once turned
on, the fan will remain on until duct heating demand drops to 0%.
During Unoccupied mode, the parallel fan will only be on when heating demand reaches
100%.
The fan stops when:
There is no duct heating call.
l During those occupancy modes where the fan is not set to run constantly or set to run
intermittently.
l For example, if the fan is set to run constantly in Occupied and Unoccupied Override modes,
then during Unoccupied and Standby modes the fan does not run and only runs when there
is a heating demand.
l The airflow setpoint rises above the sum value of parallel fan flow set point + 25% in
Occupied mode.
Note: With parallel fan VAV systems, heating airflow is provided by the fan and not the primary air.
So the heating minimum and maximum airflow settings are generally not used and should
be set to be equal to the cooling minimum airflow setpoint.
Modulating Speed Parallel Fan Sequence
An ECM modulating fan is turned on and off in the same way as the single speed parallel fan. See
the single speed parallel fan sequence for more details.
When the fan is called to run, it starts at the speed set by the minimum ECM fan speed
(FanMinSpeed AV197) on the Local Outputs tab in the configuration graphic.
When there is a call to run a stage of binary duct heat, if the minimum fan speed setting for that
stage of heat (HeatxMinFanSpeed) is greater than the minimum ECM fan speed, then
HeatxMinFanSpeed is used as the lowest speed the fan will be allowed to run at. If
HeatxMinFanSpeed is less than the minimum ECM fan speed or if that heating stage is not
currently active, then that minimum ECM fan speed is the minimum speed setting used.
If a stage of duct heat is present, the fan will continue to run at minimum ECM fan speed until the
last heating stage reaches 100%. If the heating demand continues to rise, the fan will begin to
increase its speed as an additional stage of heat until it reaches its maximum ECM fan speed
FanMaxSpeed setting. As the heating demand drops, the fan will slow down and the heating
stages will turn off in the reversed sequence.
To Next Page
Loading...
