Patent ID: 9625179
Date: 2017-04-18
CPC Classifications: F24H

Claim:
1. A system for providing a backchannel from a furnace location to a thermostat location using polarity splitting comprising: (a) a furnace, said furnace including a furnace control board; (b) a low voltage AC power source located at said furnace, said low voltage AC power source having a first phase and a second phase whereby said second phase is opposite in polarity from said first phase; (c) a furnace adapter, said furnace adapter including a polarity responsive relay and an input for said backchannel; (d) a thermostat configured to perform one or more HVAC functions; (e) a thermostat adapter, said thermostat adapter including an indicator, a first diode, and a second diode; (f) a cable of wires connecting said furnace adapter and said thermostat adapter, said cable of wires comprising a sufficient number of wires to support said one or more HVAC functions and two wires for said low voltage AC power source, said two wires for said low voltage AC power source comprising a first power wire for providing power and a second power wire for providing a common power return for said low voltage AC power source; whereby (g) said furnace control board is connected to said furnace adapter; (h) said thermostat is connected to said thermostat adapter; whereby (i) said first diode on said thermostat adapter conducts a first current produced by a selected HVAC function of said one or more HVAC functions onto a selected wire in said cable of wires connecting said furnace and said thermostat adapter during said first phase of said AC power source; (j) said polarity responsive relay on said furnace adapter responds to said first current produced by said selected wire during said first phase of said AC power source; (k) said polarity responsive relay controls a second current to said furnace control board for said selected HVAC function; (l) the state of said input for said backchannel on said furnace adapter controls a third current on said selected wire to said thermostat adapter during said second phase of said AC power source; (m) said second diode on said thermostat adapter conducts said third current from said selected wire to said indicator on said thermostat adapter during said second phase of said AC power source.