Backflow Preventer Insulation Covers by Thermaxx Jackets

Protect backflow preventers from freezing or sweating with Thermaxx’s made-to-fit removable anti-freeze insulation jackets.

Before & After Insulation Blankets Are Installed On Backflow Preventer

About Backflow Preventers

A backflow preventer device protects water (or other liquid) supplies from backflow — the undesirable flow of water in reverse direction. This function is critical to prevent supplies from contamination. We receive a lot of requests to insulate backflow preventers.  We thought we should expand on the topic since it is such a crucial part of any irrigation system.

To understand how crucial the function of the backflow preventer is, there are some key terms that need to be understood.


A cross-connection occurs when there is a connection between a potable or drinkable water system and any system containing non-potable water, pollutants, or toxins. An example of where a cross-connection would exist is the piping between consumers’ water systems and an auxiliary water system, a cooling system, or an irrigation system.

Cross-connection often occurs outside the customer service connection, such as within commercial, residential, or industrial plumbing systems. During cross-connection, water supplies become contaminated due to back siphonage or back pressure.


Backflow is defined as any unwanted reversal of the flow of liquids, solids, or gases in a piping system. Backflow in an irrigation application is when water from the sprinkler system travels “upstream” through the pipes and enters the potable water system through a cross-connection.

Backflow can cause numerous problems and lead to contamination of potable water. For example, if the nonpotable water from your home backflows into the public water supply, there is a serious issue. Backflow occurs as a result of back siphonage or back pressure.

Any chemicals or contaminants in water that backflows present a danger to the water supply they enter and to anyone who may potentially consume that water.

Back Pressure

Back Pressure is when the pressure downstream of the backflow devices exceeds the supply (or upstream) pressure. This can occur if the supply pressure is reduced, or if the pressure downstream is increased. For example, if back pressure occurs due to increased downstream pressure from an upstream source, drinking water could be contaminated with unwanted runoff that could contain pesticides or other contaminants.

Back Siphonage

Back siphonage occurs when a vacuum is created upstream of the backflow device, and water is literally sucked back up the system due to negative pressure. Back siphonage can happen when the water supply is stopped due to a water main break or nearby fire hydrant use.

Types of Backflow Preventers

The main types of mechanical backflow preventers include:

  • Reduced pressure principle assembly
  • Pressure vacuum breaker
  • Certain check valves, such as the double check valve and residential dual check valve

Many local codes and federal regulations address backflow prevention, often through requirements of backflow prevention devices and testing.

Protecting & Insulating Backflow Preventers

So why insulate?  The backflow preventer will fail if the components on the assembly freeze.  Backflow is the unwanted water flow into piping systems and is opposite to its normal or intended direction. A drop in water pressure which creates negative pressure in the water supply system causes back-flow. This loss of pressure causes contaminated liquid to be siphoned back into the drinking water through a cross-connection.

Back-flow prevention systems block this contaminated water from entering back into the water supply. This ensures that only quality water is used for drinking, bathing and food processing.  

Thermaxx backflow insulation covers prolong the life of your backflow preventer components by protecting them from the elements. Salt and rain and other chemicals may cause the valves on your backflow to begin to rust. When housed indoors adjacent to other HVAC components, the backflow preventer tends to “sweat.” This can lead to accidents in the workplace not to mention the eventual erosion that can be brought on by ongoing condensation.

To protect the life of your component and avoid costly problems caused by contamination, request a quote to insulate your backflow preventer. Unlike other backflow preventer covers, Thermaxx insulates the individual components on your assembly based on their specific design. Your initial investment will protect your components from all the challenges brought on by the elements, outdoors and in the boiler room.

Due to their critical function, regular testing of backflow preventers is required because backflow preventers have many internal and moving parts subject to wear, fouling, or damage from the environment. Outdoor backflow preventers may be especially at risk of freezing. Frozen water expands and puts additional stress on backflow preventers and can cause them to break.

Removable insulation has proven a very effective means of protecting backflow preventers from freezing. This can come in the form hard box-shaped backflow enclosures or, as Thermaxx provides, form-fitting backflow insulation jackets. For harsh winters, heat tracing is often installed to ensure backflow preventers stay in a safe temperature range.

Tips for Choosing Insulated Backflow Covers and Blankets

Insulating backflow preventers is essential, especially during cold winter months. You will want to start the process by determining how much insulation protection — the R-value — you need to prevent frosting and freezing. A good rule of thumb is to go with a higher R-value than you think you need to ensure you can prevent freezing.

Next, consider whether your water well pump is above ground. If it is, you should be more precise with insulation because you will not want to block ventilation. This issue is not a concern if you only need backflow valve insulation covers.

Measure the height, width, and length of your backflow preventer, pipes, and any other components you need to cover. Also keep in mind whether there may be prolonged exposure to below freezing temperatures.  If that is the case, you may also wish to consider heat tracing. Finally, consider the amount of room you have for insulation of your backflow cover as it will need to be properly sealed when closed.

Avoid Fiberglass Backflow Insulation Covers

When choosing insulated backflow covers, avoid fiberglass if possible. Fiberglass is not durable against UV rays, and it is heavy compared to other materials. Fiberglass is also not hydrophobic, meaning that it could potentially deteriorate due to water absorption over time.

Thermaxx Backflow Preventer Insulation Jackets

Thermaxx provides customized tight-fitting backflow preventer insulated covers for your specific needs. Our backflow preventer blankets have the following features:

  • Heat trace ready: Our cover for backflow preventers can come with belt loops sewn on the inside of the jackets, so they are ready for installation of heat tracing if needed. The specific closures for this insulation are velcro d-rings.  Thermaxx does not supply heat trace but can recommend distributors in your area. Some users don’t require belt loops but ask that the jacket fit snug over the component and heat trace.
  • The right fit: We produce covers for exact fit for many specific backflow preventer assemblies including Watts, Kennedy, and Flowmatic. We use seal flaps to connect the jacket to insulation. In addition, our skilled technicians and engineers also design jackets to exact specifications for custom jobs.
  • Convenient: Our backflow device covers are designed to be able to be removed and replaced easily and quickly by any personnel. In addition, when heat tracing is installed, the heat tracing comes off with the jacket when the jacket is removed.
  • Cost-effective: We’ll provide you with backflow covers that work best for your climate, needs, and device. Size, shape, and thickness are tailored to your needs. Being able to buy exactly the jacket you need means you don’t have to pay for un-needed insulation.
  • High-quality: Our backflow insulated covers are painstakingly designed and crafted to remain effective under harsh conditions for extended periods of time. As with all Thermaxx Jackets, we stand behind our backflow covers with a 5-year guarantee.

More benefits of choosing our covers include:

  • Failure Prevention: Our insulation jackets prevent freezing, meaning your backflow preventer will be less prone to breakage, extending the lifespan of your backflow preventer. Insulation also helps you save money by avoiding costly repairs or replacements.
  • Keeping water safe: When your backflow preventer works properly, a water supply can remain secure without running the risk of contamination.
  • Lessening service interruptions: By preventing your backflow preventer from freezing and breaking, you keep your components running smoothly. That means nothing is out of commission due to service interruptions because you have taken preventive steps.

Contact Thermaxx Today for Backflow Preventer Insulation Jackets

Do you have any questions or want to learn more about our products? We’re happy to answer any questions you have about our backflow preventer insulation covers or any of our many other insulation solutions for your facility. Each of our products is designed and manufactured in the United States. We provide custom-fit insulation jackets and turnkey implementation services for backflow preventers in numerous settings, including:

  • Schools
  • Universities
  • Municipalities
  • Hospitals
  • Large offices
  • Government buildings
  • Manufacturers
  • Commercial companies
  • Multiuse or multifamily units
  • Hotels
  • Industrial companies

Whether your company has a few local branches or operates nationally, Thermaxx is here for you. We provide high-quality insulation for backflow preventers, outdoor pipes, and other components to help you prevent damage and save money.

If you would like to request a quote, please get in touch with our team today! You can also contact us online for general inquiries.

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