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Backflow enclosures protect backflow preventers, pumps, and valves from vandalism and freezing temperatures. Backflow enclosures often referred to as “hot boxes” can be made as a cage, fake rock, or a box-like structure made of aluminum/fiberglass. Protection from freezing temperatures requires a fully enclosed backflow enclosure with a heater.

Aluminum Backflow Enclosure Hot Box by Safe-T-Cover

Safe-T-Cover Models:

How do backflow enclosure heaters work?

Backflow enclosure heaters work by adding heat inside the enclosure during cold temperatures to prevent a frozen pipe. Heaters vary from self-regulating cables to wall-mounted box heaters that have an internal thermostat. As many areas freeze at some point during the year, most enclosures should have with a heater.

When are backflow enclosure heaters necessary?

A backflow enclosure heater is necessary when the backflow preventer is located outside in any area that has freezing temperatures at any point of the year. Even typically warm weather, southern states have the occasional freeze. Therefore, most backflow enclosures should have a heater.

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*Enclosures with a "D" (ie. 300D-AL) in their product name typically are made to order and may take up to 2-3 weeks to ship. Please call for more details.

Engineering Brochure


The Formation Of ASSE 1060 Standard:

In 1996, the American Society of Sanitary Engineering released its new standard to regulate the growing backflow enclosure industry. Enclosures that were built before then were either too small, too overly insulated, or provided heaters that were not safe. In some cases, these earlier enclosures were not much more than a fiberglass box placed on top of the valves. Before this standard was released, drainage was a very big problem with enclosures as it is today for indoor RPZ backflow preventers. When this standard was released, it outlined most of the problems and how the new standard could help solve these issues. Plumbing Standards Magazine was publishing articles and information on RPZ discharge rates and the dangers of confined space in 1996. These are exactly the same problems we are experiencing today.

In 2006, the standard was updated by adding more details for testing. It also clarified that equipment enclosures designed for fluid conveying components would have to pass this standard, not just the backflow preventer enclosures.

In 2017, the standard was updated again, changing some requirements about heaters and adding additional testing requirements.

The ASSE has recommended these enclosures are installed in a fashion consistent with local codes, which mostly require they are ASSE certified. Products can only be ASSE approved if the manufacturer has applied to the ASSE and their products have been tested in their lab. The entire process can take up to 60 days and back in 1996, the cost was approximately $25,000. Once the product has passed the test, they will receive a seal of approval. This is what the approval means:

The major specifications of the ASSE 1060 are:

1.0 Classifications:

Enclosures constructed and designed to maintain a minimum internal temperature of 40°F and an external temperature of 30°F with a minimum Thermal Resistance (R) Value of 8.0.

Class I-V Freeze Protection Enclosures for pressure and atmospheric vacuum breakers.

Class II Freeze Retardant Enclosures may have or not have a heater.

The enclosures are constructed and designed to maintain a minimum internal temperature of 40°F for a 24-hour time frame with a minimum Thermal Resistance (R) Value of 8.0.

Enclosures constructed and designed with no freeze protection and No minimum Thermal Resistance (R) Value.

Class III-V Non-Freeze enclosures for pressure and atmospheric vacuum breakers.

2.0 Structural Strength:

Enclosures must be designed to support a minimum vertical load of 100 lbs per square foot (100 psf).

3.0 Drainage Capacity:

All classification enclosures must be designed to discharge water from inside the enclosure to prevent submerging the equipment. The depth of the raised water inside the enclosure cannot exceed 8-inches during full discharge of a Reduced Pressure Zone backflow preventer and must be in accordance with the following requirements:

4.0 Access for Testing and Maintenance:

Various equipment components including test cocks, valve handles, and handwheels must be within 24-inches of the access opening.

Hinged access panels must be restrained in the open and closed position.

Horizontally hinged panels and unrestrained panels must weigh 70 pounds or less.

5.0 Security and Vandalism:

Access to the internal equipment must be locked. Access should be with keyed devices or have an affixed padlock.

6.0 Materials of Construction:

Exposed Exterior Wall Panel Materials -
• Galvanized steel
• Pre-painted galvanized steel
• Aluminum
• Stainless-steel
• Natural stone
• Fiberglass reinforced plastic & Gelcoat 25% glass fiber by weight with 18 – 20 mil with
Gelcoat on the outer surface.

Case Study on placement of backflow preventer:

In this day and age, everything is in high-gear and fast-paced. More and more owners are putting a lot of pressure on architects, engineers, and contractors to design and construct projects very quickly. Everyone is held to a faster pace to get things done and in many cases, everyone starts doing the same things over and over again to save time. This is very true wit RPZ backflow preventer placement.

Also, many design items are getting little to no thought during a project. Everyone seems to be doing what they've always done before and then move on to the next item on their list. That said, there must be a change to the same-old-same-old. RPZ devices should not be installed indoors and this is why:

RPZ In A Bottling Plant:

This study showed that a bottling plant decided to move the RPZ valve from inside the building to outside the building. The device was next to the transformers and electrical panels which is why the device was being moved outside. The job of an RPZ is to dump water during normal use, so picture the device doing its job.

We spoke with over 1,000 design engineers over the past year and they were all shocked when they saw what occurred when the RPZ failed inside. This led to electrical problems facing the customer with a huge impact.

Why RPZ Devices Are Installed Inside:

Although it's common practice, it really doesn't make any sense. The reasons for installing the backflow preventer inside are actually aesthetic! RPZ backflow preventers cannot be installed underground which means they either go outside in an industrial enclosure or stay inside. Let's face it, most architects do not want eyesores on the property, so they encourage designers to place them inside and out of sight and the owners feel the same way. So, is there a potential for a disaster when the device does its job? Should they be wasting valuable time when everything seems to be running smoothly? If owners were well informed they would reconsider because aesthetics should never be a part of the equation. There are many ways to avoid an eyesore when installing a backflow outside in an enclosure.

The Device Is Being Moved Outside:

In this scenario, the RPZ valve was installed inside next to the transformers, switchgear, and electrical panels. Unfortunately, should the device fail, all will be impacted which could disrupt the running of the plant and even cause the plant to shut down for a given period of time. Typically, engineers and architects don't take into consideration that the owner's livelihood can be set on its heels and these things do happen. The RPZ backflow preventer did fail and flooded the room it was in as well as the room next to it when it blew out the wall. That room next door is where the telecom equipment was located.

When the insurance company investigated and came to their conclusions, they held the designers at fault and the insurance collected millions of dollars from them. Since then, the bottling plant is moving the device outside before something else happens. Because they initially had the device inside, the company is paying twice for it. Once for moving it inside and then the act of moving it outside The bottling plant will feel the repercussions because the plant manager and facilities director will have to shut the plant down to put the new device outside and get it in service. Needless to say, no one is really happy.

Can Risk Be Prevented From Installing The Device Inside?

The engineers can install a floor drain or floor sink. If you wonder if some RPZs dump too much water for the drains to handle, the answer is no. Let's say there are three and one is larger than the other two, you can find the flow rates for each one of the valves from manufacturers on their websites. The most logical solution is to make the drains larger though that's not always practical.

Why Run The Risk Of Installing The Device Inside?

When addressing engineers and architects, they will tell you their clients are very important to them. They want their project to be more than just successful, they want the owner to benefit from what you have constructed. So, with all the evidence that is out there, why run the risk of installing the device inside, to begin with?

I would be willing to guess that on their next project, they will not stay with the same status quo for the RPZ backflow device design. Instead, they will make decisions that are in the best interest of their client and move the device outside!

Enclosure Sizing

How To Landscape Around A Backflow Enclosures & Meet Guidelines

The best way to landscape around your backflow enclosure is to ensure you are concealing it from anyone’s view but not restricting the person who will test your backflow assembly each year.

Landscaping has become a very popular way to hide your backflow enclosures. The options are almost limitless including trees, bushes, tall grass, and other landscaping items you might think of. Even though it’s an expensive way to hide your enclosures, there are some things you must take into consideration. Local zoning laws may require the enclosures to be screened by landscaping, etc. Therefore, design professionals, certified installers, and master plumbers must check local requirements before installing backflow prevention assemblies.

As the compliance specialists for the Department of Water Resources in Lynchburg, VA, Angela Hefner is responsible for keeping up with over 3,200 backflow prevention assemblies in the city. Lynchburg expects to stay up-to-date with the best practices and procedures associated with backflow prevention assemblies. They have come up with a good way to deal with any landscape design that involves a backflow enclosure.

The Start Of Backflow Enclosures In Lynchburg

First off, RP is the Reduced-Pressure Principle Backflow Prevention Assembly (RP). Any RP required for a project, (or backflow preventer) shall be installed above ground and in a backflow enclosure. The exceptions being those irrigation assemblies that are winterized. After many years, the water department officials have discovered that installing backflow prevention assemblies in utility vaults is not exactly a good idea.

The point is, vaults flood,, rainwater fills them to a point that test cocks are covered, creating a risk of a cross-connection. On top of that, there is no safe entry, making it very dangerous for the testers.

During 2008, Backflow prevention assemblies were being installed outside and above ground in heated enclosures.

Open Discussions Are Critical

Hefner pointed out that one of the largest reservation building owners said installing their backflow prevention assemblies above ground created a real eyesore, to say the least. That said, good landscaping can keep the enclosure hidden even if it’s in a front yard. It all starts with open discussions.

As an example, if a design engineer looks to the water-purveyor or looks at all the site’s features including parking lots, traffic islands, or city streets, that is a great place to start from. That said, the design engineer should talk to a landscape architect about ways to disguise or hide the backflow enclosure.

Backflow Enclosures Must Have Clearance

Hefner believes that having discussions early on will make things a lot easier, especially when it comes to meeting the required allowances tied to backflow prevention assemblies, their required enclosures, and landscaping in Lynchburg.

In order to provide enough space around the backflow prevention assembly when being tested, the water department officials came up with distances that should be around each RP to include the landscape design and the backflow enclosure.

In The City of Lynchburg Manual of Specifications called for the following clearances around each assembly:

• Two feet in front of the outermost edge of the RP and 2-feet behind.
• One-foot on both ends of the RPZ

Bushes, flowers, trees, etc should have enough space between them and the enclosure in order to maintain the required allowances.

The allowances were finally settled upon after two things took place. With help from the International Plumbing Code, it was confirmed that sufficient space was needed for testing, maintenance, and the replacement of backflow prevention assemblies.

Discussions were held with the Master Plumbers and State Certified Backflow Prevention Device Works in the field.

Many workers complained about getting cut by branches or just could not get inside the enclosures. Hefner added that sometimes the building owner would end up with a damaged enclosure before testing could be completed.

Hefner added that this is why it’s important for owners to think about their landscape design when including backflow prevention assemblies and the related enclosures. They need to consider the types of bushes being planted as they might be small starting off but will grow. Also, they must keep their bushes trimmed to keep them at the desired size.

In turn, Hefner and her team have needed to add the following text to the site plans when backflow prevention must be addressed. Landscaping and/or other site features shall not impact the required allowances for any RP or RPGA for backflow now or in the future.

All said and done, Hefner can not stress enough how important it is for the design engineer to talk to the water purveyor and, hopefully, a landscape architect to design the perfect project. Being active and working with the design engineer beforehand, will allow you to think things through first. Over the long haul, you will probably save.

No matter where you live if backflow enclosures will play a part in your life, pay attention to the guidelines and follow the requirements to keep your area safe and happy and your pockets not being drained.