A waterbed heater, sometimes called a temperature control system, consists of a heating pad and a control unit that are used to warm the bed and maintain the temperature. The heating pad is generally made of vinyl or rubber and goes between the water mattress and the liner.
When setting up a new waterbed, it usually takes up to 48 hours for the water to reach the proper temperature. This is due to the immense volume of water in the mattress. While a waterbed heater is not specifically necessary, most people find sleeping on a cold water mattress uncomfortable. Waterbed heater control units can be adjusted for comfort depending on the individual preference of the user.