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.