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--- info:misc_heater_operating_notes [2017/11/20 20:22] – created tomgle
+++ info:misc_heater_operating_notes [2017/11/20 20:23] (current) – tomgle
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 ===== Misc Heater Operating notes =====
-The switch that switches between external and internal themostat was permanently modified by removing the black jumper from the center of the switch and attaching it directly to the external thermostat terminal.  The other poles of the switch had a black and red wire going to the controller board.  This was unplugged from the controller and a 2 pin jumper pafor ut in it's place.\\
+Tom G after some measurements on 11/20/17.\\
+The switch that switches between external and internal themostat was permanently modified by removing the black jumper from the center of the switch and attaching it directly to the external thermostat terminal.  The other poles of the switch had a black and red wire going to the controller board.  This was unplugged from the controller and a 2 pin jumper put in it's place.\\
 When the unit is powered up the  power switch displays nothing or a "P" on the LCD.  When the "P" is displayed the fan runs all the time.  When there is no "P" the external thermostat can be used to turn on the resistance coils heating them up without the fan. The overheated light soon comes on.  This in general is not a good situation.   I did some measurements on the control board and found that the "P" can be detected with the #5 relay.  When a "P" is displayed the relay is driven by -12 VDC.  There is no voltage when there is no "P".  \\