Can anyone help me with specing out a thermostat. The customer was using a Honeywell PC8900/W8900 to run the heating,cooling,humidifier,and air exchanger. W8900 went south and will not operate correctly. Honeywell has discontinued the PC8900/W8900. So does anyone know what can be used in place of it to run the same amount of equipment. I only have five wires to the main stat.

Any help would be great.

Thank, Helgy