In temperate climates we continue to irrigate during the winter. Dormant lawns still require some irrigation to maintain and protect their roots, while warm-season lawns overseeded with rye grass need a regular watering schedule.
In spite of our warmer winters, we do experience hard freezes where the temperature drops to freezing or below and stays below 32°F long enough to freeze vegetation and cause ice to form in standing water. Under these conditions water in an above-ground backflow preventer freezes and expands, breaking valves and cracking or warping the body. When the freeze is over, water starts leaking or shooting from the preventer, flooding the surrounding area. Sometimes the freeze damage isn’t apparent (for example, internal check valves in a double check backflow preventer), resulting in the backflow preventer providing zero protection until testing discovers the problem much later.
Backflow prevention assemblies (BPAs) can be turned off and drained, but it would involve setting up the valves correctly to do this, and you would have to perform this procedure every time a hard freeze is forecast. Instead, you can still protect your BPA in its regular setup by wrapping and insulating it.
How to Winterize Your BPA
With a reduced pressure zone valve assembly (RPZ), wrap the side pipes with foam pipe wrap, and tape them with heavy rubber tape. You can also use self-stick foam insulation tape, fiberglass pipe insulation, or R-11 fiberglass insulation wrapped around the entire backflow preventer. Be sure to use a waterproof tape with the insulation so it doesn’t get wet. Unlike the side pipes, the RPZ valve in the center can’t be fully wrapped — an opening must be left for the water to drain out the bottom.
An open-bottom insulated pouch is another way to add protection to an RPZ. The pouch fits over the entire preventer and leaves the bottom open for drainage and air flow. You can use small stakes to attach the bag to the ground to keep the wind from blowing it way.
A pressure vacuum breaker assembly (PVB) can be insulated in a similar way (don’t block the air vent and drain outlets), as well as an above-ground double check assembly (DCA). However, most DCAs in central Texas are installed underground in a valve box to protect them from freeze damage.
If you find yourself in a situation where a hard freeze has been forecast and you don’t have time to get to the hardware store to buy insulating supplies, you can use items from around the home to create temporary protection for your BPA. Wrap it with towels, a fleece blanket, sleeping bag, or sweatshirt. Use duct tape to keep the wrapping in place. Then place a heavy-duty garbage bag over the BPA to keep the wrapping dry. Don’t seal the bag too tightly — just enough to keep the bag and wrapping from blowing off. You can then also place a small trash can over the preventer for extra freeze protection.
Choosing the Right Insulation Pouch
Insulation pouches are also referred to as insulation bags, covers, jackets, or blankets. Here are some tips to help you choose a pouch to protect your backflow preventer assembly:
- Measure your BPA to buy the right-size pouch. Include the height from the ground to the tip of the BPA and measure the width from the outside edge of one side to the opposite outside edge, including any test cock or valve handles. To be safe add a couple of inches to make sure it fits.
- Check the R-value. A higher number indicates better protection from the cold. Any number above R-10 is good protection from solid frost. If you’re providing a wind break for the BPA with a hard enclosure, you can use an insulation pouch with an R-value lower than 10.
- Make sure the material is UV resistant to prevent UV degradation.
- Get a waterproof insulation pouch to keep moisture from the wrapping. If insulation was used, it can lose its R-value if it gets wet. It can also get moldy and start to rot.
- Grommets at the bottom of the insulation bag give you the option to secure it with zip ties or to tie it off with stakes. For security, you can attach a lock to prevent theft of the bag.
- Some insulation pouches have Velcro sides and bottoms that make it easier to put on and take off.
Hard-sided enclosures or boxes provide another type of insulation for BPAs. They’re available in various materials, such as aluminum, fiberglass, and plastic. A number of models offer designs and colors that match a yard’s natural surroundings. Because many are meant to be used in addition to an insulation pouch, it is sometimes included when you purchase the enclosure.
Some enclosures take the form of decorative rocks with interior foam walls that blend in with the landscape and can be left in place all year round. Others have locking mechanisms to protect BPAs from thieves and vandals. The more expensive ones include wall mounted heaters to prevent the pipes inside the box from freezing.
Be sure to measure your BPA accurately to get the right size enclosure. Some manufacturers will assist you with correct sizing when you send measurements and a photo of your preventer. You can also make your own enclosure and insulate it by taping R-11 fiberglass insulation on the inside or using a spray foam.
South Austin Irrigation provides expert commercial and residential sprinkler system repairs, backflow replacement and installation, and service. We are Licensed Irrigators.
Call us at (512) 534-7449 or submit our online service request form.