Differential Temperature Controller CAMPINI STX041Y00

I have absolutely no idea what you are on about...something about solar, would these be PV panels? What is the problem, simply stated? something like this?

See if these people can help you.

The difference between two temperatures cannot be a negative number, by definition.

I' am very limited in resources when it comes to electronic parts. What I experience is a string of defective components: the PTC on the (water) solar panels reads 6,5 Ohms. The PTC in the tank reads 2.500 Ohms (but reading seems very unreliable).

I wish I had some potentiometers here to test the display. (was thinking of lin. 10 or 15 kOhms).

The water in the panels is pumped into a tank and the differential temperature controller controls a water pump.

With about 2000 Ohms, I read 15 degrees C. (close) and a higher resistance reads higher temps ( so I conclude this is a PTC of about 2000 Ohms at 25 deg C)

One controller doesn't read the roof panel temp and shows - 77 *C.

Guess this has a destroyed op amp input (also the sensor died there) - Lightning, static discharge, (who knows the cause?)

I replaced 2 sensors and the controller and the man is happy. I will keep you posted when I examine the defective controller. Tks.

Controller kits are available. Mine works great. I will see if I can find the ordering information. About fifty bucks.

http://www.jc-solarhomes.com/differential_controller_kit.htm