How to add a sprinkler valve???
I assume your valves are stacked up together in some sort of manifold configuration right?
If this is the case, you can add another along the water supply line either in front or at the end of that manifold---wherever you have room. Try to minimize laying your pipe runs out of the valves over each other though.
Your challenge may be adding to the PVC ts and elbows if that is what the manifold piping is made from. If the current manifold end with a PVC elbow, you will not have anything to glue on to. You may end up having to rebuild the whole thing which is no big deal but will cost you some fitttings to rebuild the manifold and hook up again to the sprinkler lines. You will need to measure carefully.
Now is a good time to think about adding a shut-off valve for the whole system if there isn't one too! And and air compressor inlet if you need to blow your system out in a freezing climate. If your pressure is excessive you might as well added a pressure regulator too when the water is off.
Make sure the anti-syphon/backflow portions of the valves are high enough to do their thing. I see a lot of DIY systems with them too low to really meet code if anybody were to look.
Last edited by sdsester; 01-29-2012 at 06:15 PM.