Winterizing an Irrigation System
Propperly winterizing your irrigation system could save you money in repairs when springtime arrives. The backflow prevention assembly found on irrigation systems plays a crucial part in protecting the homeowner and the District from potential contamminates like pesticides, herbicided, animal feces, and even automotive fluids.
Although the winters in central Texas are relatively mild, the temperature does drop below 32 F. To maintain irrigation systems during these freezes, you need to winterize and protect above ground RPZ backflow assemblies to prevent any trapped water from freezing, expanding, and causing damage.
RPZ's can also be turned off and drained, but you need the correct valve setup to do this. Alternatively, you can wrap and insulate them. Wrap the RPZ side pipes with a foam pipe wrap, and tape them with heavy rubber tape. Some prefer to use R-11 fiberglass insulation instead. The RPZ valve itself is in the center, so don't fully wrap it, because water needs to drain from the bottom of the valve.
The best way to protect this center valve is with an insulation pouch that slips over the top of the whole RPZ, but leaves the bottom open. The bag is attached to the ground with some small stakes. To help seal off the wind, a layer of mulch can be added aroung the base of the pouch.
A type of insulating enclosure, or box, can then be placed over the "bagged" RPZ for extra freeze protection, with another layer of mulch at its base. You can either make these pouches and boxes yourself or purchase them. Some enclosures are is the form of decorative rocks, with foam wall structures, which can be left in place year around. If you make your own enclosure, you can insulate it with spray foam, or even R-11 fiberglass insulation on the inside.