eZV-440 Application Guide
Edition 2.6
Page 63 of 84
Balancing Mode
(VAV only) Occupied setpoints are maintained in this mode. However, temperature and ventilation
sequencing is overridden for some outputs based on the balancing MV objects.
Heating and Cooling (VAV)
Heating load is present when the HeatCoolLoad (AV802) value is between 0 and 100.
The available heating stages in the algorithm are sequential and are as follows: Heat1, Heat2, and
Heat 3. The heating load is evenly divided by the number of heat stages that you’ve set up. Also,
when the duct heater is turned on but still can’t meet the heat demanded by the system, an ECM
fan can act as an extra and final heat stage by ramping up its fan speed from its minimum setting to
its maximum setting based on the heat load.
When AirFlowStatus (BV800) is off, all stages of duct heating are disabled.
Cooling load is present when the HeatCoolLoad (AV802) value is between 0 and -100.
Box Mode
“Box” mode in the algorithm detects if there is hot or cold air in the duct. As a result, Box mode
decides whether opening the damper acts as a heating stage or as a cooling stage. The algorithm,
unless manually commanded, controls box mode by monitoring the inlet air temperature and
comparing it to the current space temperature.
Box mode object (MV801) can be commanded to its manual states: CoolCmd_ or HeatCmd_.
The following table summarizes how damper heating or cooling stage is determined by Box mode.
Space
demand
Box Mode
detects:
Damper Stage
Heating
demand
Hot air in the
duct, or
HeatCmd in
manual mode
Damper is the first stage of heat.
Heating
demand
Cold air in the
duct, or
ColdCmd in
manual mode
If there is a duct heater and it is not a series or parallel fan
VAV box, the damper is the last stage of heat. Otherwise the
damper will act as a first stage of cooling.
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