iWorx® VPU2
505-010-2, Effective: April 29, 2014
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© 2014 Taco Electronic Solutions, Inc.
Supply Air (SAT)
To connect the Supply Air thermistor to the unit, attach one wire from the thermistor to SAT (T16) and the other wire to
the adjacent common (T15). The thermistor used must be 10K Precon Type III.
Smoke Detector (SMK)
To connect the smoke detector switch to the digital input, attach one wire of the contact to SMK (T14) and the other
wire to the adjacent common (T15). This must be a dry contact normally open switch. This input is for indication only. A
separate smoke detector should be wired into a fire alarm system if the generation of a fire alarm is required.
Filter Status (FIL)
To connect the filter switch to the digital input, attach one wire of the contact to FIL (T13) and the other wire to the adja-
cent common (T12).
Mixed Air Low Limit (MLL)
This must be a dry contact normally open switch. To connect the low limit indication switch to the digital input, attach
one wire of the contact to MLL (T11) and the other wire to the adjacent common (T12). This must be a dry contact nor-
mally open switch.
Indoor Air Quality (IAQ)
This must be a dry contact normally-open switch. To connect the digital CO
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level sensor to the unit, attach one wire
from the sensor to IAQ (T10) and the other wire to the adjacent common (T9). For a digital sensor, this must be a dry
contact, normally closed switch. For an analog sensor, it must be of the 0-10V type.
Static Pressure (SPR)
To connect the static pressure sensor to the analog input, attach the positive wire from the sensor to SPR (T8) and the
other wire to the adjacent common (T9). The sensor must be analog, 0 to 10 volt type.
Return Air Temperature (RAT)
To connect the return air temperature thermistor to the analog input, attach one wire of the sensor to RAT (T7) and the
other wire to the adjacent common (T6).
Fan Proof (FNP)
To connect the fan proof switch to the digital input, attach one wire of the contact to FNP (T5) and the other wire to the
adjacent common (T6). This must be a dry contact, normally closed switch. If you are not providing a fan proof input, T5
and T6 must be shorted (jumpered) together.
Connecting Output Devices
Modulated Economizer (ECNM)
The modulated economizer output can be set to 0-10 V max through the control logic. Connect the positive wire from
the damper actuator to ECNM (T37) and the other wire to the adjacent common (T36). See preceding figures for
details.
Modulated Heating (HTGM)
The modulated heating output can be set to 0-10 V max through the control logic. Connect the positive wire from the
heating output to HTGM (T35) and the other wire to COM (T36). See preceding figures for details.
Modulated Cooling (CLGM)
The modulated cooling output can be set to 0-10 V max through the control logic. Connect the positive wire from the
cooling output to CLGM (T34) and the other wire to COM (T33). See preceding figures for details.
