www.DaikinApplied.com 11 OM 1280-2 • MICROTECH UNIT CONTROLLER
UVC Unit Modes
The UVC provides several “normal” modes of unit operation.
Bypass modes.
Normal UVC modes can contain a single state or several
states depending upon the functionality required for each
particular mode.
Table 6: UVC State Names and Numbers
Normal UVC modes State names
OFF OFF
Night Purge Night Purge
Emergency Heat Full Heat, Can’t Heat
Auto
Heat
Heat
Defrost
Low Limit
Can’t Heat
Cool
EconMech
Mech
Econ
Reheat
Reheat Low Limit
Can’t Cool
Fan Only Fan Only
WARNING
Off mode is a “stop” state for the unit ventilator. It is not a “power OFF” state.
Power may still be provided to the unit.
“stop” state for the unit
single UVC state: OFF.
heating, cooling, and ventilation (OA damper is closed),
and fan operation ends. The UVC continues to monitor
space conditions, indicate faults, and provide network
while power is maintained to the unit.
temperatures. If the space temperature drops below EHS
Heat mode (see “Emergency Heat Mode (Super State)” on
page 18).
NOTE: Special purpose unit modes such as Purge,
Pressurize, and De-pressurize can force the
UVC to perform “special” functions during which the
Night Purge Mode
Night Purge mode is provided as a means to more easily
and quickly ventilate a space. Night Purge can be useful in
helping to remove odor build up at the end of each day, or after
cleaning, painting, or other odor generating operations occur
within the space. Night Purge mode consists of a single UVC
state: Night Purge.
Night Purge is a full ventilation with exhaust mode, during
which room comfort is likely to be compromised. Therefore,
Daikin strongly recommends using Night Purge only when the
space is unoccupied.
When Night Purge mode becomes active, for 1 hour
cooling. If the UVC is not set to another mode within 1 hour
mode (refer to “Fan Only Mode”). Since any new energy used
to treat the incoming air would be wasted in the purge process.
In the Night Purge mode, the space fan is set to high speed,
the OA damper is set to 100% open, and the Exhaust Fan
binary output (see “External Binary Outputs” on page 41) is
set to ON.
While in Night Purge mode, the UVC does not maintain DA
temperatures. If the space temperature drops below the
EHS, the UVC is forced into the Emergency Heat mode (see
“Emergency Heat Mode (Super State)” on page 18).
Fan Only Mode
The Fan Only mode is provided so that the UVC can be forced into
a Fan Only operation via a keypad/display or a network connection.
Fan only can be entered through heating and cooling and auto. Fan
Only mode consists of a single UVC state: Fan Only.
When Fan Only mode becomes active, the UVC stops all
normal heating and cooling.
While in Fan Only mode, the UVC does not maintain DA
temperatures except to ensure that the DA does not fall below
the VCLL or based on the air tempering functionality if enabled.
If the space temperature drops below the EHS, the UVC is
forced into the Emergency Heat mode (see “Emergency Heat
Mode (Super State)” on page 18).
Auto Mode
Auto mode is provided so that the UVC can be set to
automatically determine if heating or cooling is required. Auto
mode is the default power-up UVC mode. Auto mode is made
up of the Heat and Cool mode “super states”. When the UVC
is set to auto mode, the UVC automatically determines which
mode (Heat or Cool or fan only) to use.
Figure 3: Night Purge State Diagram
Night Purge
Mode
Run Time
<1 Hour
Fan Only
Mode
Yes
Enter from:
Network Input
No
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