4
INSTALLATION CONSIDERATIONS
Power
This control 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. The W and HUM signals are taken from the Rh
power and 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. Depending on the installation, up to 14 wires may 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 not provide ordinary 24VAC. They
carry a combination of power and communications data that is unique to these
products.
