Irrigation System Winterizing

September 19, 2014

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Every year, before the first freeze, the ritual of irrigation “blow out” becomes the priority for all irrigation systems in regions located where the frost level extends below the depth of installed piping. That of course, includes us in Michigan, at the top of the list.

It’s easy to forget such things as winterizing irrigation systems. With the school year humming, holidays approaching and busy work schedules to keep up with, such winter maintenance tasks can easily slip one’s mind. However, failing to winterize is one of the most common causes of irrigation system repair. At Twin Oaks, we proactively contact you to schedule your irrigation system to avoid such.

Here are three reasons why it’s important to winterize your irrigation systems:

1. Freezing temperatures can seriously damage irrigation systems.

When water freezes, it expands. Eleven cubic feet of water will become twelve cubic feet of ice. This hydro-expansion can cause fittings, sprinklers, valves, pumps, pipes and other parts of irrigation systems to burst and break. Draining your system of all water is the only way to ensure that it will still be in working order when spring arrives. This should be conducted utilizing compressed air (see below for more details on this).

2. Your warranty could be voided if you don’t winterize.

Irrigation services recommend that you “blow out” your irrigation system rather than relying on gravity to pull all of the water out of the pipes, valves and other parts. Indeed, many irrigation services void their labor and parts warranties if the homeowner fails to arrange for blow out winterization services.

3. You can save money on expensive irrigation system repairs.

If your irrigation system freezes, the resulting expansion could cause most of the components to be destroyed, meaning that you will have to pay someone for irrigation system repair.

For these reasons in Michigan, October is the ideal month for winterizing your irrigation system.

Winterization Blow Out Method Details – AS DONE BY PROFESSIONALS

Extreme care must always be taken when blowing out an irrigation system with compressed air. Compressed air can cause serious injury, including serious eye injury, from flying debris. Always wear ANSI approved safety eye protection and do not stand over any irrigation components (pipes, sprinklers, and valves) during air blow out. Serious personal injury may result if you do not proceed as recommended! It is best for a qualified licensed contractor to perform this type of winterization method.

The blow out method utilizes an air compressor with a Cubic Foot per Minute (CFM) rating of 80-100 for any mainline of 2″ or less. These types of compressors can be rented at your local equipment rental yard. Caution: a small shop compressor (1-3 HP) will not have enough “free” air to properly winterize the system. Do not attempt to fully charge the holding tank then release the highly-pressurized air flow into the mainline to compensate for the compressor’s lack of CFM. The compressor is attached to the mainline via a quick coupler, hose bib or other type connection, which is located after the backflow device. Compressed air should not be blown through any backflow device. To start the blow out, shut off the irrigation water supply and, with the compressor valve in the closed position, attach the air compressor hose to the fitting. Activate the station on the controller that is the zone or sprinklers highest in elevation and the furthest from the compressor. Close the backflow isolation valves. Then slowly open the valve on the compressor; this should gradually introduce air into the irrigation system. The blow out pressure should remain below the maximum operating pressure specification of the lowest pressure rated component on that zone and should NEVER exceed 80 PSI.

Each station/zone should be activated starting from the furthest station/zone from the compressor, slowly working your way to the closest station/zone to the compressor. Each station/zone should be activated until no water can be seen exiting the heads; this should take approximately two minutes or more per station/zone. It is better to use two or three short cycles per station/zone than to have one long cycle. Once the station/zone is dry, you should not continue to blow air through the pipe. Compressed air moving through dry pipes can cause friction, which will create heat and could cause damage. Never run the compressor without at least one irrigation control valve open.