This document defines the product requirements for the Communicating Daughter Board. The board controls combine functions needed for establishing a communications and control link from a communicating thermostat to a non-communicating residential ignition control onto a single printed circuit board assembly. The controls provide a two-wire communication link and 24VAC to the communicating thermostat (via a 4 wire connection scheme), communication parallel tie points for a communicating indoor blower and outdoor unit, ignition control twinning input, W, W2, Y and H thermostat 24VAC outputs, status LED’s and Coil Thermistor input.