RJ
McGrath, Inc.
Newton, MA
(617) 332-3339
Lawn Sprinkler Systems Since 1957
What Makes Up An Entire Sprinkler System?
Overview
A lawn sprinkler system is set up
to water efficiently by place sprinklers in a geometric pattern around the
lawn area. Most homes do not have enough water pressure to operate all of the
sprinklers at the same time and therefore the sprinklers are separated into
groups called ZONES. (Even if a home has enough water pressure
to run everything at once it is usually better to make different zones due to
the fact that sunny and shady areas may need different watering times. As well
as a few other reasons.) Now that the sprinklers
are broken up into zones the zones are controlled by electric valves out in
the ground. These are called zone valves. The zone valves are connected to the controller by a direct
burial wire. The pipe leading to the zone valves is called the main line and
the pipe from the zone valve to the sprinklers is called the zone line. A backflow preventer
is installed on the main line. A rain sensor is also hooked up to the controller
and mounted on the outside of the building.
In
the diagram below the Blue line is the Main, The green line is the zone line
The red dots are the sprinklers and the white diamonds are the zone valves. The
Yellow triangle is the backflow preventer. The Blue Circle with the X is the
controller mounted in the garage.
Controller
There
are many different types of controllers on the market. They all can handle
different amounts of zones. If you areonly doing the front yard make sure you
get a controller that can handle the expansion of the rest of the yard. This
will prevent you from having to purchase another timer when you do expand the
system.
The
most important thing you as a homeowner are looking for is how user friendly is
the controller. Be careful with this…. What is user friendly to the irrigation
contractor may not be user friendly to you the end user. I can
program any timer that is made. I’ve been doing this all my life. There
are many controllers out there on the market today that will drive you nuts
trying to figure them out. Because of the computer shipthere is no such thing
as a feature less controller. Everyone wants to out do the other guy with
features. As a homeowner you will use about 40% of the features a controller
offers.
RJ McGrath recommends and installs the Hunter Controllers. Why? First of all it works very reliably Because people do call us to walk them through the programming process of the controller. We show the homeowners how to use it and the understand from the beginning. Don’t let the sprinkler systems controller tak you more time to figure out than dragging a hose around.
Rain Sensor
With
the price of water going up all the time, the rain sensor is one of the most
inportant parts of the sprinkler system.The rain sensor is what actually runs
the sprinkler system. You set the controller for an everyday operation and let
the rain sensor take over. The rain sensor is only as good as where it is
placed. If it does not get wet it will not shut off the system.
The rain sensor
will shut the system off when it gets wet enough.
If the system is scheduled to operate at 5am and it starts raining at 4:45am
your sprinkler system will turn on. It takes about a ¼” of rainfall for the rain
sensor to shut down the sprinkler system. Rain sensors are adjustable so if
your system constantly turns on after heavy rainfall call to get the rain
sensor checked.
Sprinkler Heads
There
are many different types of sprinkler heads available. Only 2 types are
primarily used in “lawn” Sprinklers; Spray Heads and Rotary Heads.
Some people call them lawn heads and shrub heads but that has nothing to do
with it. The major difference between the sprays and rotaries is the distance
they cover. Spray heads cover up to 15’ +/- and Rotaries (for residential)
cover up to about 35’. Actually for
shrub areas both type are not very efficient. See our drip irrigation section
for the proper watering of shrubs and flowers.
Sprays
and rotaries are not compatible as far as how they apply water and should NEVER
be put on the same zone. See the precipitation rate chart to get the real scoop.
Spray heads put down water 3 – 5 times faster than rotaries and therefore need
to run 3 to 5 times less during an irrigation cycle.
Zone Valves & Wire
Probably
the most important part of the entire system is the zone valve. This is what opens and closes every
time the zone turns on. We use a Weathermatic valve that has been manufactured
the same way since the early 1980’s. In 2001 we had Zero defective weathermatic
valves. Why would we change? They are also one of the more difficult items to
change and find during a service call. Many companies install valve boxes to
locate the valves but they only are visable for about 2 years until the grass
grows over them. We use state of the art wire tracers to locate the zone valves
if there is a problem.
One of
the things that creates valve problems is not using the proper wire connector. Water proof wire connectors
are more expensive than electrical tape but well worth it. Especially 3 years
down the road when the warranty is up and you start to pay for the service
work.
Backflow Preventer
Ugly
but imortant and it’s a plumbing code. These protect your drinking water from
being contaminated by stopping any water that gets into the sprinkler system
from getting back into your home. There are 2 types of backflow preventers
allowed for use in lawn sprinkler systems a PVB and RPA.Here are the criteria
on which one to use. First off when they do their job the are designed to dump
water. Do not let anyone install either these inside your home.
PVB – Must
be installed 12” above the highest point on the irrigation system. (nothing can
be higher than this) Less money
RPA – Must
be installed 12” above grade outside. (things on the system can be higher than
this) More Money.
Although
cost really does not dictate which one to use. Some towns have different
ordiances and only allow the RPA.