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How To Winterize A Sprinkler System With Backflow Preventer?

By Harry RamosLast update: 2024-07-11

It’s fall and the temperature is getting colder, which means that you should winterize your sprinkler system and backflow device.

I highly recommend you to have an irrigation expert winterize your system. But if you can’t get one to do that for some reason, don’t worry, you can do it yourself. Here is a quick and easy guide on how to winterize a sprinkler system with backflow preventer.

How To Winterize A Sprinkler System With Backflow Preventer

What you’ll need:

  • A flathead screwdriver
  • Foam insulating tape
  • Foam pipe covers

How-to:

Step 1: Shut The Main Valve Off

Slowly shut the water off that’s coming from the meter. You know they're in the direction of the pipe. So, if the valves are parallel to the pipe, they are on.

How To Winterize A Sprinkler System With Backflow Preventer?

Step 2: Drain Excess Water Off The Sprinkler System

There are three ways to drain the remaining water in a sprinkler system depending on the system type and features:

Blow-Out Method:

I only recommend this method to those who have experience.

After turning off the sprinkler system's main valve and the backflow preventer's ball valves, connect an air compressor and blast away any leftover water between the main shut-off and the backflow preventer.

On systems with a tested backflow preventer installation, the air compressor should be installed downstream of the backflow preventer.

Manual Drain Method

When there're manual valves installed at the end and low points of the irrigation piping, use the manual drain method.

Turn off the irrigation supply, then open the manual drain valves. Release all the excess water in the line between the irrigation shut-off and the backflow preventer.

We want to ensure that any water that might be in the pressure vacuum backflow device has the opportunity to expand without breaking the valve of the cap. So, you’ll need to release the bleed valves.

How To Winterize A Sprinkler System With Backflow Preventer?

To release the bleed valves, use a flathead screwdriver and rotate them to be parallel with the actual valve. You’ll see any expansion of water will flush out over here.

If you have a testable backflow preventer, read the manufacturer’s instructions carefully before draining this part.

Keep the ball valves off and turn off manual drain valves.

For your information, when bleed valves are perpendicular with the actual valve itself, they’re closed.

How To Winterize A Sprinkler System With Backflow Preventer?

There might be some excess water in the backflow preventer, sprinklers, and piping depending on the drain valves’ position.

Automatic Drain Method

If there're automatic drains placed at the end and low points of the sprinkler system piping, utilize this method. When turning off the water supply to the system, the drains are activated automatically.

For your information, the drains will open when the water pressure drops, releasing all the excess water in the piping. The drains close when the water pressure increases.

Do the same as the manual drain method if you have a testable backflow preventer.

Step 3: Insulate The Supply Side

To make the winterization of your sprinkler system more effective, utilize insulation.

How To Winterize A Sprinkler System With Backflow Preventer?

Foam insulating tape and foam pipe covers are easily found at any sprinkler warehouse.

Please avoid this mistake:

Many people just insulate the supply side up to the brass part, but the fact that it’s also critical to insulate the valve, too.

The reason is this valve utilizes a stainless steel ball valve to open and close the water flow. When you close this, there’s still water in that ball valve and they rest there. If this valve isn’t properly insulated, a hard freeze makes that amount of water expand and burst.

How To Winterize A Sprinkler System With Backflow Preventer?

Make the measurements, then cut the foam pipe covers to give a nice tight fit to the supply side and the valve.

You’ll need to insulate all the way up to where the pressure vacuum backflow device starts as much as possible.

Then, wrap foam insulating tape around the foam pipe covers a couple of times to ensure that you give a good tight fit to them and they’re completely covered.

How To Winterize A Sprinkler System With Backflow Preventer?

Notes:

You don’t have foam pipe covers at hand, use blankets, old towels, or other insulation instead.

If your backflow preventer is installed with unions, disassemble it, drain all the excess water from both sides, and store inside until the winter ends.

Conclusion

That’s all for this article. Now you have known how to winterize a sprinkler system with backflow preventer. I hope you find this guide is easy to understand. Thanks for reading!


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