Daikin MicroTech III User Manual

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www.DaikinApplied.com 135 OM 920-6 • MICROTECH UNIT CONTROLLER
Sequence of Operation (Modulating Burner)
5–1 Gas Burner
The following details the sequence of operation for the low
heat option.
• Unit DDC controller calls for heat
• Furnace DDC control module receives a call for heat
• Furnace safety switches and DDC control are checked for
safe conditions
• 45 second prepurge cycle starts. Proof of airow switch is
checked for combustion airow
• Spark ignitor is activated
• Gas valve receives a signal to open fully
• Burner is ignited and runs for 20 seconds in high re
NOTE: If call for heat is interrupted during this timing, the
furnace will be locked in for the 20 seconds cycle.
• Gas valve and induction blower motor receives a signal
to modulate burner output to match the unit discharge air
temperature setting
10-1 gas burner
• Unit controller calls for heat.
• Top furnace DDC receives call for heat.
• Steps 3-9 from Low Heat Option are followed.
• If top furnace is unable to meet the unit controllers DAT
heating setpoint then the furnace DDC calls for 3rd stage
of heating
• Top furnace is reduced to low re
• Bottom furnace receives a call for heat and sequences
similar to steps 3-9 from Low Heat Option.
• Staged burner gas valve receives a signal to open 50%.
• Top furnace receives a signal to modulate the gas valve
to meet the unit controllers DAT heating setpoint.
• If stage 3 and modulating furnace are unable to meet
DAT heating setpoint then stage 4 heat initiates
• The bottom furnace stages up to high re and the top
furnace reduces to low re
• Mod gas valve and inducer blower motor receive a
signal to modulate to match the unit controllers DAT
heating setpoint
Discharge Air Temperature Setpoint Reset - Heating
The Heating DAT Setpoint may be reset for units with DAT
Heating Control. The Discharge Air Temperature Setpoint
will never be set below the Minimum DAT Heating Setpoint
or above the Maximum DAT heating Setpoint on the Heating
Reset menu. The reset type may be set to one of the following:
• None: Discharge Heating Spt is user adjustable
• Network: Discharge Heating Spt is equal to the Network
DAT Htg Setpoint when it is valid
• Space: Discharge Heating Spt is based on the Space
Sensor
• Return: Discharge Heating Spt is based on the Return
Air Sensor
• OAT: Discharge Heating Spt is based on the Outdoor Air
Temperature
• Ext mA: Discharge Heating Spt is determined by a 0-20
or 4-20 mA signal
• Ext V: Discharge Heating Spt is determined by a 0-10 or
2 - 10 VDC signal
Reset reverts from Return to None when the return air sensor
opens or shorts. Reset reverts from Space to None when the
space sensor opens or shorts. Reset reverts from OAT to None
when the outdoor air sensor opens or shorts.
When Space, Return, OAT, Ext mA, or Ext V is selected, the
Discharge Heating Spt equals the Max Htg Spt when the
selected value equals the Max Htg Spt @ value. Similarly,
the Discharge Heating Spt equals the Min Htg Spt when the
selected value equals the Min Htg Spt @ value.
When Space, Return, or OAT is selected, the reset schedule
should be set so that the DAT Heating setpoint decreases as
the selected temperature increases as shown in the graph.
When Ext mA is selected, the values “Min Htg Spt @” and
“Max Htg Spt @” are entered as mA values. When Ext VDC is
selected, the values “Min Htg Spt @” and “Max Htg Spt @” are
entered as VDC values.
If Ext mA or Ext V is selected as the type of reset, the Min Htg
Spt @ value may be set above the Max Htg Spt @ value to
cause a decrease in the DAT setpoint as the external signal or
the Min Htg Spt @ value may be set below the Max Htg Spt @
value to cause an increase in the DAT setpoint as the external
signal increase.
When ever the Clg Reset Type or Engineering Units is
changed, the Min Clg Spt @ and Max Clg Spt @ values revert
to default values as follows:
• None: Min Clg Spt @=0NA, Max Clg Spt @=100NA
• Network: Min Clg Spt @=0NA, Max Clg Spt @=100NA
• Space, Return: Min Clg Spt @=73.0F, Max Clg Spt
@=71.0F
• OAT: Min Clg Spt @=90.0F, Max Clg Spt @=70.0F
• ExtmA: Min Clg Spt @=4.0mA, Max Clg Spt @=20.0mA
• ExtVDC: Min Clg Spt @=0.0V, Max Clg Spt @=10.0V

Daikin MicroTech III Specifications

General

Brand	Daikin
Model	MicroTech III
Category	Controller
Language	English