Control unit wiring
Figure 21 shows the control unit wired to a wall display unit and the HVAC system. Wire colors are typical
thermostat wiring colors. The fuse is a mini ATO 2 amp.
For heat pump HVAC systems, the orange wire (O) is the changeover valve.
Figure 21. Control unit wiring
Wall display unit
RS-485 Data +
RS-485 Data -
HVAC system transformer
Most central HVAC systems have a common heating and cooling transformer. This is the factory default
setting for jumper JP1. In some cases you may have separate heating and cooling systems, each with their own
transformer. In that case, cut jumper JP1 and wire the heating transformer red wire to the RH terminal and the
cooling system transformer red wire to the RC terminal. Wire the cooling system's 24 VAC Com to the control
unit's 24 VAC Com terminal. Do not connect the heating system's common wire to the control unit.
J4 HVAC system
W1-Heat stage 1
W2/O-Heat stage 2
Y1-Comp stage 1
Y2-Comp stage 2