Chamber heater hysteresis

  • I have a large chamber heater thats set up in bang bang mode on out8 on my duet3. The chamber heater has a controller board with a relay on it for the heater and heats up just fine. The problem im having is the relay is clicking on and off too quickly and eventually i know it will burn out. Chamber is set to 60 deg so is there a way i can set a hysteresis of say 5 deg so the chamber turns off at 60 and then back on at 55?

  • @3DDP I don't believe there is any way to alter the hysteresis. If you are using a mechanical relay, changing it to a solid state one would work.

  • Moderator

    @3DDP Are you sure it's set to bang-bang, not PWM? How often is it clicking? Please post your config.g, and if you've tuned the heater and saved it with M500, your config_override.g. Your M307 command for the chamber heater should include 'B1' to enable bang-bang mode. If using PWM mode, you can change the 'Q' parameter (PWM frequency in Hz) in M950 command that defines the heater to make the switching much slower, eg Q1 for 1 switch per second. Not sure if you can use Q0.1 (which would be switching every 10 seconds) to reduce it even more.


  • I was just wondering if the hysteresis could be changes. The relay is only clicking intermittently once the temp reaches the set point. I guess ill just have to mod the controller board with a solid state relay. Thanks everyone

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