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You are here: Home > Sprinkler School™ > Parts and Components > Valves and Valve Manifolds > How To Replace An Irrigation Valve
How To Replace An Irrigation Valve

How To Replace An Irrigation Valve

Valves - Parts and Components

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In-line Irrigation Valves

In-Line Valves


Red Arrow indicates
water flow direction

Anti-Siphon Irrigation Valves

Anti-Siphon Valves


Red Arrow indicates
water flow direction

Replace the Valve, or Just the Guts?


There are two ways to replace a valve, either replace the top (guts) only with new parts or cut the entire valve out and replace it with a new unit. There are only a few parts that can go bad on a valve, the diaphragm, the solenoid and perhaps at times the ports. All these parts are located on the top of the valve. The body is simply a pipe molded to the shape of a valve and nothing ever really goes wrong with the body of the valve. A smart, quick recommendation is to find the exact same valve, same model, and brand to swap the insides out of the faulty valve. To do this simply unscrew or unbolt the top of the defective valve and take out the diaphragm and replace it with the new parts from the new valve. Voila! you now have a brand new valve with the least amount of work.

The top consists of a solenoid, diaphragm and then the plastic casing or molding at the top of the valve. In addition there is a port (a tiny tube) at the top and a filter screen in the diaphragm that has a tendency to get clogged. If your valve is acting up you may want to start by cleaning the interior of the valve of any dirt or debris that may be causing the valve to malfunction. Swapping out the guts with a new model is the simplest method to replace a valve. The problem you may run across is that by the time your valve needs to be replaced your model may no longer be manufactured. Valves can last and run for many years. If you are in a hurry and want to replace the valve immediately and do not want to search for the same brand and model you can replace the entire valve unit.

There are two types of valves un-threaded (slip) or threaded. If you have a slip valve that is glued in you will have to cut the valve out on both the inlet and outlet ends. This will require you to glue one end on and put on a coupler and extend the pipe, flex it and glue it in place. If the valve is threaded then you can cut one side off and hopefully you have enough room between the valves in a valve manifold to attach the new valve. If you have dug deeply enough in the ground during the installation and have also left room between the adjacent valves then you can untwist the faulty valve and remove it from the pipe. If the valve is too tall to turn take the solenoid off and then continue to twist it off. Reattach the new solenoid once the threaded valve has been re positioned. The other side will have to be cut and a coupler attached and it flexed on and glued into place.

The absolute best way to work with valves is to create manifolds, then you can easily break the connections loose and pull out the faulty valve, screw in the new one and reconnect the parts, finish by screwing them back on tightly. If your solenoid has burned out we highly recommend replacing the valve guts at the same time, because once the solenoid goes the diaphragm may start to go bad soon as well.

When installing a valve it is important to know that all valves (anti-siphon and inline) are marked with arrows to illustrate which direction the water must flow through the valve. If the valve is not installed correctly the valve will not work.


Go with the Flow


Be careful when replacing a valve that you put the new valve in correctly... facing the right direction. On almost every valve there are arrows marked on the body indicating the flow of water, there is a true inlet and outlet on every valve. If you install the valve incorrectly the valve will not open or the valve will stay open and not close. If a valve is installed incorrectly, against the flow of water it will typically remain closed. If you are not sure which way the water is flowing in the ground pipe then pay attention to where the solenoid was located on the old valve and also to the direction the arrows pointed on the old valve.

The solenoid is always located on the outlet side of the valve (a few valves have the solenoid located on the side) turn the water off before you begin to replace a valve and then relieve the pressure by going to the controller and turning on one of the zones, if you don't want to walk back to the controller you can unscrew the solenoid on the valve which will open the valve manually. It's always good to have a hand pump handy when working with valves. When the valve is removed the water will still be at full pressure on the inlet side of the valve (from the water supply to the valve). Even if you relieve the pressure that pipe will have water inside it. When you turned the water off and turned on a zone, you just relieved some pressure in the pipes. So when you take the top off a valve or cut the valve out the hole will fill with water. If you didn't dig a very deep hole, the hole will fill with water which will also pour into the valve along with dirt and debris creating additional work and clean up. Have a hand pump ready when working with valves, rotors and sprays. With the right tools you can save yourself unnecessary problems.


Slip or Threaded Valves?


It really doesn't matter if you use a slip or threaded valve, it's basically personal preference. Some people think threaded valves are easier because they like to put a number of valves together to create a valve manifold. The valves when joined as a group create a T formation. People tend to try to squeeze as many valves as they can into one valve box. The valves must be positioned very close together which does not leave extra pipe to work with when a valve needs to be cut out and replaced in the future. Running out of workable pipe is a common occurrence in irrigation repair and replacement.

And having to re-pipe a section to get the job done may be necessary aspect of replacements. Using a threaded valve offers you the option of cutting out just one side and having to re-pipe and glue just the other end. This can give you more pipe to work with and less work having to re-pipe. The problem even using a threaded fitting is that sometimes the valves are positioned too close together preventing you from being able to screw the new valve on because it hits the adjacent valves (even with solenoid removed). When installing your valves it's always a good idea to leave yourself a little extra pipe and to space out the valves with a little breathing room so that you can at least do a couple of repairs without having to completely re-pipe a section.


Valves with or without Flow Control


We recommend flow control valves, even though they may be considered a beneficial "luxury" item. Typically on a sprinkler system you will have a series of several valves. One valve may control rotors and another may control sprays. The water supply and pressure is the same for all the valves. So, let's say you are working with 60 psi. Rotors need to run around 50 psi (or as stated by the manufacturer). You will lose a a few pounds of pressure through valve and about 5 pounds through the vacuum breaker and another few pounds through the piping which will bring you down to the perfect pressure to run your rotors. So you don't need flow control for the valve that will control your rotors unless your supply is very high (which is uncommon).

The valve that controls the sprays will also have around 50 psi running into the heads, far too much pressure to run your sprays. Sprays need around 30 psi to run optimally at the heads. Too much pressure will pulverize the water droplets and will create mist or fog. Droplets of water that are too fine and will float away in the wind. With a flow control valve you can adjust the pressure of the flow with the flow control knob or handle. Simply screw down on the flow control handle which will create a pressure drop across the valve. You will be able to watch as the fogging / misting condition subsides and a normal spray output begins to emerge. Simply screw the knob until the fogging stops.


What is a bleed screw?


Some valves are equipped with a bleed screw. This screw is located on the top of the valve and can be turned on manually to open or close a valve. Screwing it tighter will close the valve, unscrewing it will open the valve. It's basically a manual turn on. It can also be used to relieve pressure, (another way to relieve pressure is to unscrew the solenoid)


The Wiring


The majority of valve problems are due to bad wiring. If a valve is malfunctioning check the wiring first. And remember to always use silicone filled connectors known as "grease caps" to connect your wires. Also, when wiring your valves remember that the two wire leads attached to the solenoid are not positive or negative. It does not matter which wire is attached to the common wire or which wire is attached to a particular valve in a zone. For more information go to How to wire valves.

Irrigation Valve Wiring Diagram

Irrigation Valve Wiring Diagram

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