RJ
McGrath, Inc.
Newton, MA
(617) 332-3339
Lawn Sprinkler
Systems Since 1957
How the Rain Sensor Works
Rain Sensors are only as good as where
they are placed.
They are a very
simple device and rarely go bad.
You can test a
rain senor by pushing down on the stem
while the system
is running. When you do this the zone should shut down.
If you know how
a rain sensor works you will understand how to troubleshoot them.
There are a bunch of wafers inside a
cylinder.
At the bottom of the cylinder is a
switch.
When the wafers
get wet enough,
they expand putting pressure on the switch,
shutting of the controller.
The Cylinder is
adjustable.
The taller you
make cylinder the more the wafers need to expand
or the more rain
it takes to shut it off.