Delta Controls eZFC-424R4-24, Application Manual

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enteliZONE Sequence of Operations
Page 64 of 84 eZFC-424R4-24 Application Guide
Edition 2.6
Interlocking Fan Speeds for Multiple Speed and ECM Fans
Interlocking fan speed settings allow you to set a specific fan speed for a heating or cooling stage.
On the Local Outputs tab, there are additional supply fan settings to enable fan speed interlocks,
specifically in the HeatxFanMin and CoolxFanMin fields where x is the heat/cool output stage
number.
By default, when duct heating or cooling output is set up, the default fan speed interlock
(HeatxFanMin or CoolxFanMin field) for that duct stage is automatically given a value of 1 (for
single and multiple speed fans) or FanMinSpeed (for ECM fans). Space heating stages are left
unchanged at the value of zero. This ensures the fan stage is always running for the duct heating
and cooling stages.
When HeatxFanMin or CoolxFanMin equals zero for active stages, the current fan speed will not
change when that heating or cooling stage x is active.
As a result, in some cases, higher fan speeds may remain unused at the end of active heating or
cooling stages. The algorithm takes this into account and uses these unused fan speeds as the final
heat or cool stage. This is referred in this application guide as the “unused fan capacity”.
ECM Fans
When an ECM fan is running, the fan speed is at least its minimum fan speed or whatever greater
value is entered in the FanMinSpeed field in the fan settings section.
Any value larger than the FanMinSpeed in the HeatxFanMin/CoolxFanMin fields will cause the fan
to run faster when stage x is active (also known as interlocking). However, any value between zero
and FanMinSpeed will cause the fan to run at FanMinSpeed.
The behavior of an ECM fan running in intermittent mode is described in the following table and
images. Even though the images only describe heat stages, the cooling stages are identical in
behavior.
Heat/
Cooling
Stage
Occupied Mode Unoccupied Mode
Binary
Fan turns on at FanMinSpeed
when there is a duct heating or
cooling demand.
Turns off when duct heating or
cooling demand is 25% to
reduce overshoot.
Fan turns on at 100% duct stage load at
FanMaxSpeed and turns off when the
demand drops down to 25%.