Even though we don't get incredibly harsh winters like our neighbors just to the north, winter freezes can do a number on poorly prepared systems during the season. If you fail to get your system properly winterized, water left in pop up head components could freeze and damage the diaphragm seal system. This can result in poor water pressure in the system and leaks prevent the system from working properly. Our Germantown sprinkler repair team gets called in for spring services for just this reason.
The most common issues with freezing temperature occur in the above ground portions of the system including the sprinkler heads, rain and freeze sensors and backflow devices. Sprinkler heads are notoriously easy to break if there is water left in them. Expanding ice can chip the spray heads, break the seal around the solenoid, crack the riser or even push the entire head off the main line. The best way to prevent this is to make sure that all of the water is out of the heads prior to a freeze. Even the pressurized water in these lines can freeze if there is loss of pressure in the system.
Rain and freeze sensors generally don't get affected by freezing temperatures but if water pools up in them and then freezes it can cause them to crack. Covering them with plastic bags or removing them altogether are the best options to prevent them from being damaged.
The number one freeze problem is usually the backflow device. It sits above the ground in an area that will be exposed to the coldest temperatures. Because the water in the device isn't pressurized it will freeze, and if there is enough of it, will damage the interior seals. This can lead to a huge, moderately expensive, leak that will need to be fixed the coming spring. Covering the backflow device with insulation and a plastic garbage bag can save you from this unpleasant outcome.
The best thing to do to keep your system in good condition is to keep a keen eye on the weather and prepare your system when the cold winds of the north venture down our way.