Servo/Fan Wiring to Jack


 
PShin said:
Any suggestions why the damper was fully open when it had shot past the 225 set point? When I mess with the setting on ambient temp (not connected to grill) , the damper seems to open and close as it should.
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You say that the fan was off but the damper was open. What was the PID output and are you still running with "Servo fully open at 100%"? If it is supposed to not be open it is possible the servo is getting stuck. For that, make sure your damper opens and closes smoothly with no stickiness and that the screw on the servo arm isn't too tight causing the damper to bind.

If it is actually still open because the PID output said it should still be open, that usually means ramp up was so slow that you had a lot of I-sum buildup that takes a long time to unwind (slow ramp up means slow ramp down after overshoot too). That assumes you have changed the Servo Fully Open At parameter to something lower. I can't say much else without knowing the other configuration params and seeing the graph (or even better, the PID internals at the time. Press 'P' on the home screen while logged in to enable PID internals):
 
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