Daikin MicroTech MT2300 - Page 12

OPERATION
MICROTECH 2300 UNIT CONTROLLERDAIKIN APPLIED
12
seconds), the fan will operate at the dehumidication setting, the
compressor will energize at full load operation and the control
board hot gas reheat output is energized to open the hot gas
reheat valve, sending hot gas to the reheat coil. The return air is
cooled and reheated to near space temperature. When the space
humidity setpoint is satised the compressor will turn o󰀨 and the
fan will operate according to its fan setting.
During smart dehumidication operation, a call for cooling will
close the hot gas reheat valve and the unit will resume normal
cooling operation until the space temperature is satised.
Simplied Dehumidication (Thermostat
control only)
This mode helps control space humidity by reducing the CFM
as the space temperature approaches the thermostat cooling
setpoint without hot gas reheat. The return air temperature
must be 68°F or greater for 1st stage operation. A multi-stage
thermostat is used to provide compressor cooling with multiple
airows. Using a 3 cooling stage thermostat the following occurs:
On a call for 1st stage cooling (Terminal TB1-3, HST on the
MT2310 I/O expansion module), the H6 output on the MT2300
board enables the pump or motorized valve to direct water ow
through the heat exchanger. The fan starts immediately (unless
it is already on) at the dehumidication CFM. If the return air
temperature is 68°F or greater, the compressor starts after the
60 second ow timer and the 360 second compressor minimum
o󰀨 timer has expired. The compressor minimum on timer of 180
seconds starts. On a call for cooling, stage 2 (Terminal Y1), the
fan output will increase to the cooling stage 1 CFM. On a call for
cooling, stage 3 (Terminal Y2), the fan output will increase to the
cooling stage 2 CFM. The unit attempts to satisfy cooling at the
lowest possible CFM for maximum dehumidication. When the
room setpoint conditions are satised, the compressor will shut
o󰀨 and the fan will either shut o󰀨 (fan switch “AUTO”) or continue
to run (fan switch “ON” or conguration switch SW2 is OFF).
Humidistat Controlled Dehumidication
This mode helps control space humidity by using space humidity
sensing and by reducing the CFM by use of a humidistat in lieu of
a thermostat. The humidistat control replaces stage 1 thermostat
control as described above in simplied dehumidication
operation. The TB1-3, HST terminal is controlled by the
humidistat enabling dehumidication fan speed with compressor
operation. The return air temperature must be 68°F or greater.
Waterside Economizer
This mode requires the optional factory-installed waterside
economizer (WSE). A hydronic economizer coil, 3-way motorized
valve and a entering water temperature (EWT) sensor are added
to the unit.
For single stage SmartSource units with WSE
option
Hydronic cooling operation is adjustable between 50°F and 70°F
via BACnet (factory default of 65°F).
• On a call from Y1 or cooling stage 1 setpoint, and the EWT
is below the hydronic cooling setpoint, but above 45°F, the
unit will operate in hydronic cooling mode. (The 3-way valve
is energized and the fan operates at the hydronic cooling
CFM setting).
• On a call from Y2 of the thermostat or second stage cooling
setpoint, and the EWT is below the hydronic cooling
setpoint, but above 45°F, the unit will operate in hydronic
cooling mode and full load mechanical cooling. (The fan will
operate at the full load cooling CFM).
If at any time the EWT rises above the entering water
temperature setpoint plus 5°F (while operating) or below 45°F,
the 3-way valve will de-energize, disabling WSE operation.
If WSE is not available due to entering water temperatures out of
range, the sequence becomes:
• On a call from Y1 or cooling stage 1 setpoint, the unit
operates at full load mechanical cooling. (The fan will
operate at the full load cooling CFM).
On a call from Y2 or cooling stage 2 setpoint, status the same as
above.
For 2-stage and Two Compressor SmartSource
units with WSE option
Hydronic cooling operation is adjustable between 50°F and 70°F
(factory default of 65°F).
• On a call from Y1 or cooling stage 2 setpoint, and the EWT
is below the hydronic cooling setpoint, but above 45°F, the
unit will operate in hydronic cooling mode. (The 3-way valve
is energized and the fan operates at the hydronic cooling
CFM setting).
• On a call from Y2 of the thermostat or BAS cooling stage
2 setpoint, and the EWT is below the hydronic cooling
setpoint, but above 45°F, the unit will operate in hydronic
cooling mode and part load mechanical cooling. (The fan
will operate at the part load cooling CFM).
• On a call from Y3 of the thermostat or cooling stage 3
setpiont, and the EWT is below the hydronic cooling
setpoint, but above 45°F, the unit will operate in hydronic
cooling mode and full load mechanical cooling. (The fan will
operate at the full load cooling CFM).
If at any time the EWT rises above the entering water
temperature setpoint plus 5°F (while operating) or below 45°F,
the 3-way valve will de-energize, disabling WSE operation.
If WSE is not available due to entering water temperatures out of
range, the sequence becomes:
• On a call from Y1 or cooling stage 1 setpoint, the unit
operates at part load mechanical cooling. (The fan will
operate at the part load cooling CFM).
• On a call from Y2 or cooling stage 2 setpoint, status the
same as above
• On a call from Y3 or cooling stage 3 setpoint, the unit goes
to full load mechanical cooling. (The fan will operate at the
full load cooling CFM).
The minimum o󰀨 timer of 360 seconds starts. If the loop
temperature increases above the changeover temperature,
waterside economizer mode will be suspended and the unit will