Jon Klima, Owner
360 Trout Lane, PO Box 23, Guffey, CO 80820
Phone: 719 479-2281,  Email:
In business for 39 years


• Article 3 - July 1990


Using 3 K ohm sensors with an IE C-30 controller and checking out the output circuit of an IE C-100©


In my May TECH NOTE, I discussed using 30 K ohm sensors with the C-30 controller. I also asked if you could figure out at what storage temperature the system would shut down if the high limit were set at 180 degrees F and if 3 K ohm sensors were used. The answer is the controller would shut the pumps off at about 118 1/2 degrees F. It is at this temperature that the C-30 would see a 3 K ohm sensor resistance of about 1168 ohms (a 10 K ohm sensor resistance is 1168 ohms at 180 degrees F). As for a practical application for this, how about using this set-up for pool or spa heating? Here, the 105 degree high limit setting would translate into a 55 degree setting while the 180 degree setting would translate into a high limit of 118 degrees. If you should ever do this however, please, please, leave a note on the controller as to what you have done. Pity the next service person who runs into such a modification without warning!


This month's TECH NOTE involves testing the Independent Energy C-100. It is quite common for the triac output device in the C-100 to be leaky, i.e., with no load on it, you will measure 120 volts AC across the output, assuming the sensor input is such that no output should be present. If however, you load the output with a light bulb (60 or 100 watts is fine), and the voltage goes to 0 volts, the output is probably OK. If this is the case, change the sensor input to give an output. The light bulb should then come on.


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