iWorx® HPU3
502-035, Effective: February 21, 2012
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© 2012 Taco Electronic Solutions, Inc.
Low Pressure Alarm (LP)
To connect the Low Pressure alarm to the digital input, attach one wire of the contact to LP (T10) and the other wire to
the adjacent common (T9). This must be a dry contact, normally open switch.
High Pressure Alarm (HP)
To connect the High Pressure alarm to the digital input, attach one wire of the contact to HP(T8) and the other wire to
the adjacent common (T9). This must be a dry contact, normally open switch.
Heat Pump Power Transducer (POW, optional)
To connect the power transducer to the unit, connect the positive wire from the sensor to POW (T11) and the other wire
to the adjacent common (T12). The sensor must be provided and configured by Taco. It is required if the HPU3 needs
to report energy usage to a GHP1 for COP calculations.
Space Temperature (ST, optional)
To connect a thermistor (Precon II or Precon III) to the analog input, attach one wire of the sensor to ST (T7) and the
other wire to the adjacent common (T6). The thermistor can be used if no TS300 series thermostat is being used.
Supply Air Temperature (SAT, optional)
To connect a thermistor (Precon III) to the analog input, attach one wire of the sensor to ST (T13) and the other wire to
the adjacent common (T12).
Connecting Output Devices
Stage 1 & Stage 2 (S1, S2)
The outputs for the stages must be connected to 24 VAC pilot relays if the load is greater than 1 Amp for each pump. If
the load is less than 1 Amp, connect stage 1 to S1 (T28) and adjacent COM (T27), and connect stage 2 to S2 (T26)
and adjacent COM (T27)
Reversing Valve (RV)
The output for the reversing valve must be connected to a 24 VAC pilot relays if the load is greater than 1 Amp. If the
load is less than 1 Amp, connect the reversing valve input to RV (T29) and adjacent COM (T30).
Fan (FAN)
The output for the fan must be connected to a 24 VAC pilot relay if the load is greater than 1 Amp. If the load is less
than 1 Amp, connect the fan input to FAN (T31) and adjacent COM (T30).
Dehumidification (DHUM)
The dehumidification mode output must be connected to a 24 VAC pilot relays if the load is greater than 1 Amp. If the
load is less than 1 Amp, connect the fan input to DHUM (T25) and adjacent COM (T24).
Modulated Fan (MFAN)
The modulated fan output can be set to 0-10 V max through the control logic. Connect the positive wire from the fan to
FANM (T35) and the other wire to COM (T36).
Other Connections
Network (LON)
Network wiring must be twisted pair. One network wire must be connected to terminal NETA (T1) and the other network
wire must be connected to terminal NETB (T2). Polarity is not an issue since an FTT-10A network is used for commu-
nications.
