Friday, January 04, 2013

Irrigation Repair 101

Third in my series of home repair items ... the rain sensor for my irrigation system. The function of the sensor is to detect rain - and then inhibit the operation of the irrigation system for a period of time, so that the system is not on unnecessarily.

It had needed to be relocated from it's old position - and as part of reconnecting it, I though I'd test it as well.

Unfortunately, it didn't want to work in the new location. Rather than buy a new one, I thought I'd open it up and see what the problem could be.

They are quite simple devices ...

  • a sensor, which consists of a number of fabric type discs stacked on a rod
  • when the discs are exposed to water they expand
  • which in turn presses a micro switch
I disassembled the unit - and tested the micro switch - which was all ok. This particular one has the three leads: 
  • one common
  • one for a normally open circuit
  • one for a normally closed circuit
This picture shows the bottom of the pole protruding into the chamber which houses the micro switch.
The discs themselves also seemed fine. I gave everything a clean, and reassembled.

And here finally is the result - the irrigation controller showing the rain symbol.
I can only guess that the process of relocating the sensor disrupted it in someway. But, a working sensor makes for a happy gardener.

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