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Avoid Costly Irrigation Repairs in Freezing Weather Conditions
All Sun City Anthem homeowners are blessed with the presence of some type of landscape watering system. With most blessings, however, there are costs or burdens to bear. That system is composed of a number of parts. One of those (described below) is not merely susceptible to freezing but is a critical assembly part that will break under freezing conditions, causing your landscaping lines to fail and unwanted flooding to occur. The good news is that there is an inexpensive or cost-free fix. Homeowners are cautioned to take certain precautions in order to avoid costly repairs, or in the event of failure, to make their own repairs using a readily available repair kit from Star Nursery.
Between the contractor installed irrigation valves, which are buried (pictured at left) and covered with a lid, and the main landscaping water line coming overhead through the garage's attic and exiting through the exterior wall, there should be installed a device called the pressure vacuum breaker valve, or PVB valve. The valve's function is illustrated here.
One critical purpose of the PVB valve, also known as a backflow preventer, is to prevent contamination hazards from backing up and entering the household's potable watering system.
The placement of the PVB valve in the watering system is depicted in the below image, with the heavy lined arrow pointing upwards to the PVB valve.
As many homeowners have learned, this PVB valve typically fails in freezing weather conditions. In years past, some homeowners incurred plumber bills totaling several hundred dollars to repair this problem. Fortunately, there are alternatives to spending that much to replace one or more $0.50 pieces of broken plastic within the PVB valve.
You should be aware that the plastic internal assembly parts of the PVB are designed to break if freezing conditions exist, protecting the expensive brass body from cracking and breaking, saving time and money. The parts are easy to replace and instructions are provided in available repair kits (see below).
Prevention. If you wish to avoid the freezing problem, I recommend you take a simple step to prevent the problem from occurring or reoccurring in the future, assuming you have not already done so. When the PVB valve is exposed to the frigid air, the water in the open line to the valve will freeze, causing some internal plastic parts to crack. One way to avoid that is to take an old carpet piece or a heavy blanket or towel or something similar that can be wrapped around the valve and reduce its exposure to the surrounding air. You may wish to add plastic wrap to keep the wrap dry when it rains.
While there is an inlet shutoff valve just in front of the PVB valve that can be turned to the off position, I do not recommend using that valve. That valve might be difficult to move, would possibly necessitate draining the PVB valve using the testcock (see above diagram), and practically speaking, you may wish to avoid the nuisance of closing and opening the testcock and repeating that process again and again as the temperature changes during the winter months.
If you are interested in following the drain procedure for freeze protection, typically only required in colder climates, or if you plan to be gone during the winter months and wish to shut off your landscape watering system, Click here.
Fortunately, you can avoid that hassle by simply wrapping the PVB valve with some type of blanket and leaving it alone. Just forget it. Here I have used an unneeded packing blanket to cover the line and valve on both sides. In the bottom and lower right hand corner of the image, you can see the covers to the buried sprinkler valves. The additional warmth provided by a blanket should prevent the plastic parts in the PVB valve from cracking during those freezing nights, saving you the high plumbing costs of needed repairs.
Do Nothing! What if I do nothing and take my chances? That's certainly an option and it may succeed. Another possibility is that you wrapped the valve with an old shirt and the valve still freezes after all—the shirt failed to provide enough protection from the weather. If for some reason your landscaping lines stop working during the winter and we have experienced freezing weather conditions, the chances are excellent that your PVB valve failed.
How would you know about that failure? You or your landscaping contractor should be able to see evidence of flooding where the PVB valve is located. Also, a sudden unexplained rise in water usage would be another sign. That flooding will be ongoing However, that evidence would depend on how much and how often you water your trees and shrubbery in the winter months. If you've taken no precautions and we've had several days of freezing weather at night, you might want to trip your garage controller during the day as a test to see if everything is OK, or ask your landscaper to perform that test. That would be true regardless of whether your garage controllers are set in the "on" or "off" positions since those controllers only control the sprinkler valves that are buried in the ground after the water has already passed through the PVB valve.
What if the PVB valve fails?
If water inside the PVB assembly should freeze, damage to the assembly and the system may occur. Water inside the PVB freezes from the outside-inward. As the ice forms and expands, this causes a buildup of pressure and the results are cracking and breakage of parts inside the valve called bonnets and poppets. Proper draining procedures (recommended primarily in colder climates) and applying insulation from freezing using some type of protective enclosure or material are two methods of freeze protection.
Homeowner options include:
Star Nursery, on the west side of Eastern between Pebble and Wigwam, sells a repair kit that should fit all Sun City Anthem homeowner PVB valve requirement. That kit (shown at left) is a Wilkins 420 Repair Kit for $29.99. It's use should resolve 99% of all freezing related valve problems. Easy to follow instructions are included with the kit.
In the unlikely event you do not have a Wilkins 420 PVB valve, you can check on the internet for kits that are available for your type valve.
If you have a Wilkins PVB valve, then you should have a model 420 valve since that valve that was used with 3/4" sprinkler water supply lines that were included with the home. In some cases, the name and model number stamped on the valve may be on the back side facing the garage, which makes identifying the valve difficult. If you do not have a Wilkins valve, please let me know.
After shutting off the main line water and removing the screw-on cap on top of the PVB valve, you will be presented with an array of internal parts, several of which you will replace from your repair kit. Here is a picture of the parts contained within the PVB valve, showing their relative position, as well as a listing of the parts included in the Wilkins Repair Kit. While the assembly looks daunting, it's not. After replacing the "old" parts with those included in the Kit, merely put all of the parts in the same order as shown.
Ron Johnson, 5 December 2010