(read thoroughly before attempting)
The backflow preventer is the plumbing device attached to the outside wall of the house and is the source of water to the irrigation system. Because this unit and the copper piping attached to it are exposed to the air, this unit can freeze and burst in less than an hour of below freezing temperatures. During the spring and fall, outside temperatures can often dip below freezing during the night. If you see forecast temperatures below 32 degrees, it is important to follow the draining procedure below to prevent costly damage to your system.
- Turn off main shut-off valve to the system (A), typically in your basement, often in the furnace room.
- Remove or open the drain plug (E) on the piping outside.
(You may have a spigot instead of a plug in which case open the spigot)
- If it is a plug please place the plug on top of your irrigation timer.
- Turn valves (C) & (D) to a 45 degree angle (half open-half closed) position. Turn test cocks to a 45degree angle also. Test cocks have a recessed flat head screw, you will need a flat blade screwdriver to turn them.
- You should get the water out of the copper down pipe (that is the pipe going into the ground) by running your irrigation timer. Force the timer to do a manual run and let the timer run through a complete watering cycle. Do not expect water to come out of the heads. This step is intended to drain the down pipe to grade level.
This procedure will protect your backflow preventer during freezing temperatures either before you have your system winterized in the fall or after you start up your system in the spring.
If no water comes out of the backflow when you are trying to drain it – that means that it is already frozen
– – – you should not leave it frozen – the water inside it will continue to expand and may burst the backflow. To unthaw the backflow – reinstall the drain plug or in the case of a spigot close the spigot, close the test cocks with a flat blade screwdriver, run your irrigation system using the manual run of the timer while slowing dumping two to six 5 gallon buckets of super hot tap water over the backflow -once the system is running (spraying water from the zone that is running on your timer) you know that it is unthawed. Then follow the above procedure for “draining the backflow” again. Disclaimer: We cannot guarantee that this will prevent all freeze damage, especially if you have PVC (plastic pipe)- that is very fragile and can damage easily when water freezes. The longer the temperature remains below freezing the greater the chance that freeze damage will happen and less chance the draining the backflow procedure will be successful.