Wiring TrueIAQ, VisionPRO IAQ, or Prestige, using the intelligent control to program humidity calls with heat, cool, or on demand. ONLY NEEDED IF SYSTEM’S THERMOSTAT DOES NOT ISOLATE Y FROM G. IF NEEDED, BREAK THE THERMOSTAT G TO SYSTEM G CONNECTION AND ROUTE THROUGH HUMIDIFIER AS SHOWN. HE150/HE250 USES A 15 VA TRANSFORMER WIRED INTO 24V IN.