add throttling of elements below a specific temp if outside the pid control window

config.py

@@ -228,3 +228,13 @@ automatic_restart_state_file = os.path.abspath(os.path.join(os.path.dirname( __f
 kiln_profiles_directory = os.path.abspath(os.path.join(os.path.dirname( __file__ ),"storage", "profiles")) 
 #kiln_profiles_directory = os.path.abspath(os.path.join(os.path.dirname( __file__ ),'..','kiln-profiles','pottery')) 
 
+
+########################################################################
+# low temperature throttling of elements
+# kiln elements have lots of power and tend to drastically overshoot
+# at low temperatures. When under the set point and outside the PID
+# control window and below throttle_below_temp, only throttle_percent
+# of the elements are used max.
+# To prevent throttling, set throttle_percent to 100.
+throttle_below_temp = 300
+throttle_percent = 20

lib/oven.py

@@ -793,6 +793,10 @@ class PID():
         elif error > (1 * config.pid_control_window):
             log.info("kiln outside pid control window, max heating")
             output = 1
+            if config.throttle_below_temp and config.throttle_percent:
+                if ispoint <= config.throttle_below_temp:
+                    output = config.throttle_percent/100
+                    log.info("max heating throttled at %d percent below %d degrees to prevent overshoot" % (config.throttle_percent,config.throttle_below_temp))
         else:
             icomp = (error * timeDelta * (1/self.ki))
             self.iterm += (error * timeDelta * (1/self.ki))