Greenhouse Plumbing

We have a unique challenge here with hot (100 degrees plus F) weather in the summer.  Not unusual for our "cold' tap water to be 85.  We are using a 1 1/2 HP chiller to recirculate the nutrient water from each of our 6 grow systems in the greenhouse every four hours. 

3 of the tanks are 75 gallons, 3 are 55 gallons.  We are using a Rain Bird sprinkler controller to turn valves on and off automatically.  Input valves are controlled as "normal" stations on the controller on one program; the "return" valves are controlled in a simultaneous program running as a "drip" program.  May be hard to understand but sprinkler controllers are programmed to only have one valve open at a time to avoid water pressure issues.  The controller does allow a "drip" cycle to run simultaneously with a main cycle, in essence, allowing multiple valves to be opened at one time.  We are using a pump start relay connected to the controller that will "turn on" the pump upon activation of a valve.  This is a normal feature of the Rain Bird that is connected to well water versus normal city water fed by pressure.  This whole set-up may be a new and unique application for the Rain Bird in a hydroponic greenhouse.

We will also have "manual" on/off switches for each valve to allow for nutrient mixing and system flushes which will allow us to open and close each solenoid manually.  We don't anticipate running the chiller all year round so the Rain Bird controller is in use for 4-6 months a year - the main growing season for our "Berry House"