How And Where To Install Valves

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K-Rain Indexing Valve

​Let's start this section by pointing out that every automatic valve has a specific direction of flow. Indexing Valves have an inlet port on the side that's pretty obvious, and zone or exit ports on the bottom. Check the instructions for a diagram of the ports to be sure. Solenoid Valves have direction-of-flow arrow printed or stamped somewhere on the body of the valve (the bottom piece which has the inlet and outlet ports.) The direction of flow can also be determined by the location of the solenoid, which is usually on the outlet side of the valve. Caveat: it's possible that there's some obscure valve out there that's constructed differently, but I've never seen one. Manual valves generally don't have a recommended direction of flow.

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Hunter XC Master Valve terminal

Master Valves
The first decision to make about valves in the planning & design process is whether to use a Master Valve. A Master Valve is an additional solenoid valve that's located at the beginning of the irrigation main supply pipe. The main purpose of a Master Valve is to prevent catastrophic leaks and loss of water on the main pipe. The Master opens simultaneously with the zone valves, so it's closed during the time that the sprinkler system isn't operating. So the majority of the irrigation main isn't under constant pressure the majority of the time. During operation, the irrigation main will only be experiencing dynamic pressure, which should be less than static pressure. Most modern irrigation timers have the capability to run a Master Valve. There will be an extra wire terminal marked P (pump) or M/P (master valve or pump.) don't worry if it's a P terminal, the timer will be able to power either a Master Valve or a Pump Start Relay. The timer will have an output capacity of around 1,000 mA. Most irrigation valves require 350 – 450 mA inrush current to open, so 1,000 mA will be more than enough. Check the timer's manual or look on the wall-wart transformer to be sure.

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​Manifold vs Satellite Configuration
The second decision in the design process is where to locate the zone valves. The are two configurations you can choose from, the manifold or satellite setup. A Manifold is a construction of multiple valves side by side, usually situated in a rectangular valve box. In a regular size valve box, typically 12” x 17”, 4 valves can be comfortably installed
with plenty of room to maintain or repair them. I've seen 5 or 6 valves in a regular valve box before, but in my opinion that's too many, and often results in the box having to dug out for anything more than a solenoid replacement. Be sure to leave plenty of wire length in the box and stretch the wires out, use extra lengths of wire if necessary, with grease filled wire nuts, of course. A 'jumbo” valve box should be used for more than 4 valves; usually up to 6, maybe 7 valves can be comfortably situated. Jumbo valve boxes can be up to 16” x 29” for the top opening. ​When using a manifold configuration, be sure to leave enough room between your pipe fittings to insert a coupling if the valve must be replaced. If the valves you're using have threaded ports, be sure to leave enough room between the valves to spin the valve off it's fittings when replacement is necessary. You can remove the solenoid before rotating the valve off it's inlet threaded male adapter or nipple. (I personally prefer to use female adapters with threaded 2” nipple instead of male adapters.)

Valve Manifold Configuration

Valve satellite Configuration

It's usually best to cut the outlet side pipes for a replacement, and a union is great to install on the outlet side when using threaded valves.
It should be noted that manifold configurations usually use more pipe to get from the centralized location to each zone, but less wire. Bundled irrigation wires are acceptable to use, if the distance from the timer is within the specs for the smaller wire. A satellite configuration is where each zone valve is placed in the vicinity of the zone that it's supplying. This config uses less pipe but more wire. Larger single strand irrigation wire is typically used since longer wire runs are involved. Also, the irrigation main supply pipe will be longer for a satellite config. Larger properties and commercial installations usually satellite the valves. Each valve can be placed in a 7” or 10” round valve box, although I've seen two valves in a 10” round box (kinda tight in there.)

Order of Components
The order of components on the irrigation main is: supply point > backflow preventer > pressure reducing valve > master valve > zone valves. The pressure reducing valve is an optional piece that may be necessary if the supply pressure is too high. The master valve is optional as well, a safety feature to prevent loss of water from a main line leak. The other variation is when using Anti-Siphon Valves. These valves are a combination of solenoid valve and backflow preventer, so a central backflow preventer at the beginning of the system isn't necessary. Check your local codes, some cities or states prefer ASVs over Double Check Valve type backflow preventers.