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Are the heating elements in Cotes dehumidifiers modulated from 0–100%?

Some Cotes dehumidifiers do not use continuous 0–100% heater modulation. The heater’s primary role is to maintain the correct regeneration temperature, while overall energy efficiency is achieved through smarter system control on some units.  For units with PTC type heaters there is no controller for the heater as this heater type is self-regulating.

What happens if you do not have stable control of the regeneration heater? 

In adsorption dehumidifiers, the heater defines the regeneration temperature, which is critical for drying the rotor. 

  • If heater power is reduced → regeneration temperature drops  
  • If temperature is too low:  
    • the rotor is not fully regenerated;  
    • drying capacity decreases;  
    • the unit may run longer or fail to reach the desired humidity level.  

            How are the heaters controlled?

            For machines equipped with PTC-Heaters there is no heater controller. The reg. air temperature is based on the airflow over the heater. PTC-Heater is found in: CRB-Line, CH-Line, CL26, CD26 and C30.

            For C35 in Basic, the heater controller is not 0-100% modulated. The heaters are regulated by physically switching a portion of the heating group off.

            For C35 in PLC config, the heater group is mounted with a SSR relay which by the PLC is controlled in a PWM type control. This ensures that the heater control is modulating 0-100% dependent on the actual heating need.

            Both on basic and PLC config, the heater group is mounted with an SSR, but the heater controllers are different. For Basic type machines a set of parameters determine if the SSR has a full output of 10V or 0V. For PLC config, the SSR is controlled in a PWM type control. This ensures that the heater control is modulating 0-100% dependent on the actual heating need.

            Both Basic and PLC config are controlled in the same way. When comparing to C35 and C65V2, it is done differently. The heating group is divided into three groups: instead of controlling each with an SSR, 2/3 of the heating groups are on/off and the last one is controlled by an SSR relay with a PWM control. So rather than having one large heating group controlled by one SSR, the C105 is controlled in a cascade type control.