Daikin MicroTech II Operation And Maintenance Manual page 21

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esCrIptIon of peratIon
Figure 14: Econ state operation (occupied mode and auto fan)
Discharge Air (DA) Heat State (State 4)
The DA Heat state is a "normal" state during Cool mode. The DA Heat state typically is
active when reheat is required to maintain DATS during the Econ mode, while maintain-
ing required minimum OA damper position. The DA Heat state can also be made active
if the optional CO 2 DCV feature is provided and CO 2 levels are high, requiring the OA
damper to open beyond what is required for economizer cooling.
When DA Heat state is active, the UVC uses the units heating capability as needed
to maintain DATS. The CO 2 demand controlled ventilation function (optional) is ac-
tive (see "CO 2 Demand Controlled Ventilation (optional)" on page 33), and the OA
damper is adjusted as needed to maintain the CO 2 set point.
Low Limit State (State 15)
The Low Limit state is a "non-normal" state during Cool mode. The Low Limit state
typically follows the DA Heat state when heat is unavailable or when the UVC reachess
100% heat and still cannot maintain VCLL.
When the Low Limit state becomes active, the heating output is set to 100% capacity
and the Low Limit logic overrides the OAD minimum position (see "Outdoor Air Damper
Operation" on page 32) and adjusts the OAD toward closed as necessary to main-
tain the DAT set point (see "Discharge Air Temperature Control" on page 29).
Cant Cool State (State 12)
The Cant Cool state is a "non-normal" state during Cool mode. The Cant Cool state
typically becomes active when primary (economizer) cooling is not available (or dis-
abled) or when an IAT, DAT or OAT sensor failure occurs.
When the Cant Cool state becomes active, no cooling is available.
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