Every year before the first freeze of the year, you will need to take extra steps to ensure that your irrigation system does not submit to the cold wintery temperatures. In fact, people who own systems where the temperature extends below the depth of the installed piping call this period “blow out.”
It’s absolutely essential that you drain all water out of the irrigation system. Even a small amount of water can freeze and burst through the pipes. Polyethylene pipe is installed in most freezing climates because it’s more flexible. Make no mistake, it can still burst if the proper steps are not taken. Furthermore, water that is left in the backflow assembly can damage and crack the brass body.
You will need to take several steps to ensure that your irrigation system is ready for the harsh wintery months. This is mandatory and if you do not take these steps, then your system will suffer expensive damage.
Manually Drain the Valves
You will start by shutting off the water supply and then open all of the valve drains. This will drain all of the water out of the main line. Then once that water has been drained, you can open the boiler drain valve or the waste valve in order to remove the water between the valve and backflow device.
All of the backflow devices on your system will have a test cock that can also be opened to drain even more water. Your sprinklers might also have check valves that you can open.
Once you have drained as much water as possible through these manual valves, you can close them.
Blow Out the System
You will need to remove all flow sensors before blowing out the system since they can be damaged by the high pressure air. Always wear eye protection to protect you from potentially serious eye injury.
Attach the air compressor to the mainline using a quick coupler. Just be sure that you are behind the backflow device because you should never blow compressed air through the backflow.
With the compressor valve in the closed position, you should attach the hose to the fitting. Close the isolation valves and then open the compressor value to slowly add air to the system. Air should be gradually introduced into the system.
What Not to Do!
Here are some things that you should not do when blowing out your irrigation system.
- Don’t let the pressure being introduced to the pipes exceed 80 PSI if the system is built using PVC pipe and 50 PSI if the system uses polyethylene piping.
- Don’t leave the flow sensors installed when blowing out the system. You should remove them and seal the pipe to avoid damaging these costly sensors.
- Never stand directly over components when putting the system under pressure.
- Never leave the air compressor unattended. This can lead to costly damage.
- Don’t blow out the system through the backflow device. You should always blow out the system and then drain the backflow.
- Don’t leave the manual drain valves open after blowing out the system.
These steps are important to making sure that your irrigation system survives the harsh temperatures of winter. This is also a good time to have a professional inspection of the system done to ensure it’s prepared for winter.