Sprinklers 101


Don’t know much about sprinklers?

This guide to the basics
will help you make the right choices

 Please see our Inventory Page for a partial list of what’s available at out Retail Outlet

Controllers | Wiring | Valves | Valve Boxes | Sprinklers | Drip Systems | Pipe | Fittings | Backflows | Automatic Drains vs. Winterizations | Point of Connection | Pumps | Choosing a Contractor


Annie Baker, proprietor

The Sprinkler System Controller is the computer brain of the irrigation system.  The timer, as it is also referred to, tells which zones to turn on when and for how long.  Some older model sprinkler timers were single program, meaning all zones would have to run the same amount of times per week, though each zone could be run during that session for different amounts of time.  These older models were generally wheel type with gears and motors.  These timers are still around as these models, at least up until now, had available parts and were fairly simple to repair, generally just replacing a timing motor, rapid advance motor or microswitch or gear.




Newer timers are in general multi-program controllers.  At first only dual programming controllers came out but now 3 programs are fairly standard on any new residential line controller.  This has allowed huge flexibility in water usage to fit a residential landscape’s need.  These controllers allow for instance, running sunny areas once day, shady areas or drip systems 3 times a week and newly seeded areas 2 to 4 times a day.  However, not much can be repaired when these fail.  There are a few tricks to try and most recently modular controllers have some replaceable parts, but if the computer board goes bad, generally it is just time to buy a new one.

My theory is, this is the easiest thing to replace so if you want to save a dollar or 2 go to a box store, go ahead and see how it works out for you.  The problem may be that these less expensive controllers are sometimes way less flexible with programming.  Also, unless you have a manual, your sprinkler contractor or maintenance personnel may not be able to program it.  I have seen this with even retail line RainBird Controllers, like the PC-104.


Sprinkler system wiring is a low 24 volts and is not hot unless the timer is running zones.  The wiring is what signals the valves to do what the controller has been programmed for.

Sprinkler system wire for residential systems is generally 18 gauge multi strand uf ul wire made for direct burial.  Some larger residential systems or systems that require longer runs from the valves to the controller may require 14 gauge single strand uf ul wire also made for direct burial.  Waterproof underground splices are suggested.  Any splices should be made within a valve box for easier location should there be any electrical issues. Water proof connectors will help preserve the life of a valve solenoid.

I have seen thermostat wiring used for sprinklers and it can be very painful to troubleshoot and replace.  Use only direct burial 18 gauge or 14 gauge wire.


Electric remote control valves vary greatly in parts availability and failure rate.  The valves are the mechanical means by which the water flows to the heads or does not.


They are contained within valve boxes if properly installed.  I have seen some mounted in basements and some on outside walls, but valve boxes with gravel bedding is the industry standard. While some installers will place valves all over the yard, one per 10″ round valve box, this can become quite complicated when wiring problems, mainline leaks, or valve failures occur, as grass often grows over the boxes and finding them can be quite costly.  Generally, valves are placed in groups called valve manifolds so to minimize wire and mainline runs.  Charged mainline running through out the yard is not generally convenient.

Valve parts if available are valve bonnets, valve stems, solenoids and diaphragms.  Valve bodies are rarely damaged unless frozen or run over.  Retail line valves often do not have parts available and  often quit being made, at which point, parts are not available as even a new valve can no longer be bought to part out.  Replacing a valve rather than a part of the valve is a much more major undertaking, as pipe needs to broken into and realigned.  I suggest major brand name contractor line valves be used so that parts are always available. Remember, some major brands like RainBird have a retail line and a contractor line.  When purchasing valves, look for warranties and parts availability.  RainBird contractor line, Hunter, Weathermatic, Richdel (also Hardie, Irritrol) contractor line or Toro contractor line have available parts.  I can still get parts for a lot of these that have not been made in 20 years.

You may be able to save a dollar or 2 on valves, but this is definitely not the place to scrimp because water cost and repair will cost you so much more than the savings.

Valve Boxes

Valve boxes are installed at ground level and have a lid which allows access to the valves, much like a man-hole cover.  Standard residential sizes are 6″ round, 10″ round, 12″ standard, and jumbo.  Each of these generally has an extension available which is a shorter version that sits atop the box and lid still fits.  These are handy for grade changes to raise the box to grade for accessibility.

Unfortunately, each manufacturer has a different fitting lid. The lid is generally what gets broken, so finding the exact valve box lid that fits your box can be painful.  Replacing the entire box is costly.  So note the brand name of your boxes before the dog or lawn mower chew them up.  Some common valve box manufacturer’s used in my area of the country are Ametek, Carson, Allied, NDS, and RainBird too has recently came out with their own valve box.


Sprinklers, also called heads come in 2 basic varieties, rotary heads and spray heads.


Rotary sprinklers are generally gear driven, though impulse sprinklers still exist, seemingly being phased out by manufacturers as costs forthese are rising and gear-drives dropping. What these 2 have in common is they turn and are generally made for larger areas of lawn, at least 18 ft or more.   Impulse sprinklers sit in cans and are driven by a flapper arm.  While their advantage over gear drives is that they can be somewhat disassembled and repaired or cleaned, they require much more maintenance, especially near bark beds, as the mechanical elements are open and not enclosed in the can and debris enters jamming the workings of the head.  Some claim too that the close watering near the head enables further spacing of heads. Also, these impulse heads can pass dirty water much easier without gumming up the mechanics of the sprinkler head.

Gear driven sprinklers are closed in case and vary greatly in ease of adjustment and quality, as with all sprinkler components. Some have


replaceable seals, but in general if they quit turning or adjusting, they are dead heads and replacement is necessary.  My favorite residential head is the Hunter PGP, but the RainBird 5000 is adequate and less expensive.  While I can adjust Toro Rotary Sprinklers, I do not have enough experience with them to rate their performance. There are mini rotors made to cover 12 ft to 30 ft areas but bear in mind, the smaller gear teeth are  in general more volatile to damage.  The latest Hunter PGJ has proven a little more reliable, but if you prefer the RainBird 3500 again these are less expensive. One should consider spray heads, which are less expensive and more dependable in any case of 18 ft or under if water gallonage is not too restricted.  Water source is critical in these decisions.  Once again I need to let you know that there is a danger in buying any sprinkler component from a box store, as many contractor brands carry 2 to 5 year warranty, which your local box store cannot support without a lot of paper work and time.

Spray sprinklers are made to cover 4 ft to 18 ft and are incredibly reliable.  There are no mechanics involved, except seals and those are easily replaced if not bought at box stores. I really like the RainBird 1804.   The only problem that can arise with any spray head is contamination or physical damage as driven over or chewed by the dog.  If you need to save 50 cents on a spray head, go ahead and support a corporate box store, except the nozzle may or may not be changeable.  You need to be able to change the nozzle to adjust for your specific area you want irrigated.   There are an incredible array of nozzle choices and between RainBird and Hunter you will be able to fit to your area of irrigation.  I suggest at least a 4″ pop-up to clear the grass, especially for lower angle nozzles.

Drip Systems

Once again box stores can hurt you with the a package drip system. Personally, I think this is ridiculous, as you purchase odd size pipe that is often impossible to repair and strange brand name drip appliances that will never again be found except in a kit, at least in the northwest.

Industry fitting standards for 1/2″ drip pipe are solid, and I cannot tell you how many times people have insisted that I have the wrong fittings, because this is THE 1/2″ pipe.  Well, if Lasco, Spears, and Dura fittings don’t work, then you’ll be scrambling for something that does, and good luck with that.

Drip systems require a drip filter and a pressure regulator so as not to plug the small drip nozzles and not blow the emitters off the pipe.  RainBird has recently came out with a combined unit that is compact for fitting in the valve box and more economical than the 2 units.

Drip Systems are only as complicated as human preference.  I have personal preferences based on my personal landscape, and landscapers agree and disagree.  You only need to know what you like.  I have large beds with compact planting and therefore have 1/4″ tubing that runs through out each bed and emits water every 6 inches. Some prefer the micro sprayer that does adjustable spray from 2 ft to 8 ft as the RainBird XS-series. The best full circle micro sprayer I have come across is the RainBird XSTS series or true spray as they are called.  If the water supply is ample, 1/2″ threaded adjustable bubblers are also nice, plumbed in hard on a poly fitting.  I really like the Toro universal bubbler for price and versatility.  Others with less complex landscapes prefer a drip emitter at every plant.  Still some treat landscape beds as lawn and use sprinklers on risers to blow over the plant and on to the grass.  There is no right or wrong, only preference for exposed sprinklers where you know it’s working or prefer the irrigation be less obvious and tend your plants knowing when they are under watered.  Some though complain of the complication of raking beds when small tubing needs to be avoided..


Once again, the box stores can kill you, both with polyethylene  pipe (hereafter referred to as Poly) and Poly vinyl Chloride pipe (hereafter referred to as PVC).

The mistake that I have seen over and over is buying utility poly grade pipe.  Utility grade has no industry standard to uphold and it varies greatly with each manufacturer, where as NSF is held to a national standard.  Utility grade pipe may be fine or it may not, but when you have 1000 ft or more in the yard including around the house I don’t like the odds.  Especially considering a charged mainline around the house, this is risky business.

PVC pipe follows as above with the addition that box stores sell 10′ sticks without bell ends.  This means you need to glue on couplings every 10 ft instead of being able to glue 20 ft sticks together without the extra cost of fittings and remember every joint can fail.  The less joints the better.  They may also try to sell you on Sched 40, the thickest wall, completely bullet proof but increases pressure loss dramatically.  Unlike poly pipe, the inside diameter is sacrificed for the extra wall thickness where as poly pipe adds the extra density to the outer diameter only.

I suggest using NSF poly pipe for the lateral lines and PVC class 200 for the mainline because of the less friction loss on the PVC charged mainline and the space it saves in filling a valve box. Since lateral lines will be the most pipe in your yard it is good too that poly pipe is more forgiving if a sudden freeze surprises you, as it has a bit of flex opposed ot PVC which can shatter for miles.


Heads should never be placed directly on the pipe in lawn areas, as this does not allow proper height adjustment to grade.  Swing pipe or funny pipe has been developed and the huge carbon content allows a miraculous amount of flexibility to get the head exactly to grade.  The irritrol swing pipe has proved to have incredible flexibility without kinking, though every major sprinkler brand makes their own these days.  I have no experience with box store swing pipe so cannot speak on the quality here.



Poly fittings also vary greatly in quality.  Buy a fitting from a box store and compare to one you get from your local


plumbing shop and you will see the difference indensity.  Although industry standards insure a 1″ fitting, they do not insure a wall thickness.  This can result in cracked fittings.    Oetikers are generally accepted industry standard to secure poly fittings.  Once again, buy only Oetiker brand as I have seen lesser brands break on the back, being welded rather than stapled.  The tool


is a little pricey, but it will pay for itself over and over again on the price of having to buy screw clamps.  Although oetikers are a little harder to remove that is only true until the screw clamp gets rusted shut. The ease of installation and the price far exceed any advantage screw clamps have.  There are a few instances in a drip system where screw clamps are better, but in general, oetikers are the way to go for clamps.    Mainline should be triple clamped and valve outputs should be double clamped.  Anything on the lateral lines are fine with a single oetiker.    Saddles have become very popular because they are very easy to install, simply snap them on, and drill in the second piece.  I suggest muscling a true poly insert fitting in, as saddles tend to become brittle with age and sometimes leak.  With the price of water these days, I wouldn’t consider


it.    There is a trick to gluing PVC fittings, which I will not go into here, but use medium body glue and standard primer.

To repeat from the pipe section, heads should never be threaded straight on to the pipe, ground thrusts will make a head to high and it will get mowed.  Swing joints can be purchased assembled, which allow a screw type height adjustment, and in commercial settings this is generally necessary for the stronger rotors to be on such a solid PVC yet adjustable assembly.  However, most residential systems will be fine with both sprays and rotors attached to swing pipe and swing fittings or funny pipe and funny fittings as they are also called.



Any community or municipal water system will probably require a backflow, and they are a good idea.  These prevent water from the lawn being sucked backed into your house water and then the city water system.  Consider the fertilizer and pet scat that could seep in given a draw on your irrigation lines.  However, I also feel some water companies go a little overboard with the type of backflow required.  A few years back here in Missoula MT, they quit accepting double check valve assemblies (DCV) and required either a pressure vaccuum breaker (PVB) or a reduced pressure principle assembly (RPZ) here.  Unfortunately, PVBs need to be installed 12″ above the highest head and in this mountain country, many times the only choice  now is an RPZ if this 12″ requirement is not feasible.

Not only are RPZs very pricey compared to the DCV and PVB, but also a 1″ RPZ takes 12 pounds of water pressure away.  A marginal water


source makes this quite costly for number of zones and good functioning of the sprinkler system.  A retrofit will be very costly, as a system designed for 12 more pounds of pressure will need a lot of rework.

Once again, buy only brand name backflows.  Especially if it is a PVB as these are fairly easily repaired if parts are available.  Wilkins and Watts have been around for a long time and have accessible parts.  RPZs are unfortunately harder to repair.  Try once, but if it doesn’t work buy a new one.

Automatic Drains vs. Winterizations

Many believe they can save yearly on the price of winterization by installing Automatic Drain Valves.  However, the problem is you never know when they are plugged up and not releasing the water.  Also, many crevices within valves, heads and pricey backflows can hold a little water regardless of a functioning drain.  It is possible that given a great negative grade, all will be well through freezing temperatures, but you need to know that it is truly draining even in this case, so perhaps gate valves to open or close at the lowest points may preserve your system.

Personally, I think it is better to put the freeze insurance in the hands of an able contractor.  Make sure your contractor guarantees his winterizations for freeze damage.  If you pay the money for winterization, winter damage not caused by a leaky shutoff valve or a home owner error should be taken care of by any reputable sprinkler contractor.

Compressed air is necessary to blow out a system of all water.  What matters is the volume of air that is delivered to completely fill the pipes and force all water out.  It is not a pressure issue, but a cfm (cubic feet per minute) issue.  An average residential sprinkler system should be blown out with at least 100 cfm compressor, one valve at a time.  Some larger systems require 185 cfm compressor or better.

Point of Connection

A licensed plumber should get your water supply out of the house and in most Municipal areas, a permit is required. Here in Missoula MT, a homeowner can take one out or else a licensed plumber is required to draw the permit.

This connection is critical to the preservation of your foundation, and this is another place to spend the money and not let a fly by night uninsured contractor run a charged mainline out of your house.  However, plumbers not being sprinkler contractors, you need to make sure your plumber knows exactly what your contractor needs.  A brass full-port ball valve is a good choice for most residential homes, sized as per your water supply.



If a booster pump, centrifugal pump, or submersible pump is a necessary component of your system, find a qualified pump man to install and again, make sure he knows what kind of water supply you or your sprinkler contractor are looking for.

Centrifugal pumps are sold at many box store outlets, but again, finding good specifications or parts can be difficult to impossible.  Invest in your pump with a contractor line pump and any changes to the sprinkler system or repairs on your pump will be easier for you in the long run.  Grundfos, Jacuzzi, Red Jacket,Meyers, Flint and Walling, Goulds, to name a few have proven themselves to be good product in this area of the country.

Choosing a Contractor

A Sprinkler contractor should be insured, have worker’s comp and a contractor’s license, as well as a history of success in your area.  Taking the least expensive bid is seldom a good choice, as it will not pay off in the long run.

A water test is necessary, simply measuring the size of your pipe is not always accurate.  Other factors could be at play.  Make sure your contractor knows exactly what you expect and understand the warranty he offers.

One thought on “Sprinklers 101”

  1. Thanks Missoula Sprinkler! This is fabulous! Everyone else seems to confuse me, or talk down to me. Hoarding information to make more money? Hiding what they don’t know?

    Even if I have you do the installation, this helps me understand what I want, and how to plan.

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