4
INSTALLATIONCONSIDERATIONS

Power

Thiscontrol is poweredby 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 operatewithout these 2 connections. Rh and Rc are
connected via PCB breakoutjumper. See Fig. 1. For applications using two
24VACtransformers,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.The W and HUM signals aretaken from the Rh
powerand the G signal is taken from the Rc power.If Thermidistat Control 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. Dependingon the installation, up to 14 wiresmay be
required. Installation as two--piece unit is recommended. Only 2 wires are
required for connection between Display Module and Equipment Control
Module.These two wires (V+ and Vg) do notprovide ordinary 24VAC. They
carrya combination of power and communications datathat is unique to these
products.