3
INSTALLATION CONSIDERATIONS
Power
This Thermostat is powered by 24VAC only. It requires 24VAC (Rh and/or Rc and
C terminals) of the low−voltage transformer to be connected to it for proper
operation. It will not operate without these 2 connections. Rh and Rc are connected
via PCB breakout jumper. See Fig. 1. For applications using two 24VAC
transformers, one in the indoor unit and one in the outdoor unit, connect the
common from each to the C terminal. Connect R from the indoor unit to the Rh
terminal. Connect R from the outdoor unit to the Rc terminal. Then, break jumper
on the circuit board (Fig. 1). The W and HUM signals are taken from the Rh power
and the G signal is taken from the Rc power. If Thermostat has been installed in a
two−transformer application that is later changed to a single−transformer
installation, installer must install a field supplied jumper between Rc and Rh.
Depending on the installation, up to 14 wires may be required. Installation with the
Two−Wire Relay Module is recommended. Only 2 wires are required for
connection between the thermostat on the wall and the Two−Wire Relay Module.
These two wires (V+ and Vg) do not provide ordinary 24VAC. They carry a
combination of power and communications data that is unique to these products.
Fig. 1 − PCB Breakout Jumper
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