What is the difference between the 243-8-2 and the 243-8-1-2

including Lochinvar Knight (KBN)

Proper timing ensures the blower starts only after the heat exchanger has reached temperature or stops only after the residual cool air is dispersed from the ducts

To maintain the integrity of the carbide heating element

Bard HVAC MC4002-AC Controller 326058-756 What is the difference betweenThe Bard HVAC MC4002 AC Controller is a professional grade solid state dual unit lead lag controller engineered for mission critical environmental control. Designed to manage two independent Bard wall mount units, this controller ensures balanced compressor runtime through automatic lead lag rotation. The "AC" designation indicates the factory integration of both the base alarm board and the Ethernet communication board, providing technicians with