Let’s face it. Backflow preventers are essential for safeguarding our water supply, but they’re not necessarily glamorous. Many contractors try to camouflage them into the landscape, maybe behind a bush or in a shadowy corner.
Others go a step further to hide them entirely below ground — also known as pit installations. Not only are the backflow preventers out of sight, but they are also less likely to be tampered with, and they’re insulated during cold weather. Win, win, win, right?
Not exactly. Pit installations can pose some serious problems. So, before you go below, consider the following.
Pitfalls of pit installs
Lack of accessibility: Here’s your first pitfall — What are you going to do for testing and repairs? You’re restricted by safety regulations and limited with access to the valve for routine or even casual inspection. To enter the pit, a respirator may be needed, critters may be present or you could be knee-deep in mud or standing water. You may even require an OSHA permit to enter these confined spaces, which takes up even more of your time and budget.
Potential for cross-connection: Pit installations create a higher risk for a cross-connection to occur. This is not because of valve failure but because pits are inherently prone to filling with water, rainwater or otherwise. Even with a low-hazard backflow preventer, such as a Double Check (DC) or Double Check Detector Assembly (DCDA), the possibility of a cross-connection is very real if test cocks become submerged. With a Reduced Pressure Principle Assembly, a submerged relief valve can cause the cross-connection.
More corrosive: Bottom line, you want to get the longest lifecycle possible from your backflow preventer. All valves, no matter where they are installed, will be exposed to the elements and face the possibility of corrosion. A pit-installed valve can be more prone to corrosion if moisture is consistently present in the subsurface pit. This constant moisture can speed up the wear and degradation of your system, which is costly to replace and hazardous to the potable water supply.
Low-hazard only applications: Most jurisdictions limit pit or below-ground installations to only low-hazard applications (DC/DCDA). High-hazard applications requiring a Reduced Pressure Principle (RP) or Reduced Pressure Detector Assembly (RPDA) are never recommended for pit installations. They run the risk of water discharge filling the pit and cross-connection from the relief valve being submerged. Local and regional governments legislate over the placement of such valves. It is not uncommon for an AHJ (Authority Having Jurisdiction) to change code, requiring an unrepairable DC/DCDA to be replaced with an RP/RPDA. Ultimately, this would force the entire installation to be re-installed above ground.
Advantages of n-Pattern backflows above ground
Smallest footprint: One of the most significant advantages of an n-Pattern backflow preventer is its compact size. An n-Pattern backflow offers a substantially smaller centerline dimension than an inline backflow. This smaller foot-print enables it to be installed in tight places, taking up less valuable real estate. It’s lighter, too, making the contractor’s job easier.
Cost saving: When installing an n-Pattern backflow preventer, some key benefits can lead to cost savings. Using a setter designed explicitly for use with an n-Pattern backflow preventer eliminates the need for concrete thrust blocks. You’ll reduce labor costs with an easier installation. Also, if an enclosure is needed, n-Pattern backflows are roughly 50% to 70% smaller compared to the inline enclosure. A smaller enclosure equates to a lot less cost.
Easier to maintain, repair, secure and conceal: Nearly any required maintenance, necessary repair or testing can be done above ground without problem or risks. The n-Pattern can also be secured easier with a shorter chain or lock, thanks to the gate valves being located closer together. And since the valve has a smaller footprint, it can be concealed behind landscaping or small enclosure.
Flow performance: Now you’re probably wondering how the flow works with the n-Pattern’s angles. Surprisingly, there’s not much difference in comparison to their inline counterparts. The flow path is more natural through the n-Pattern design. That’s because of how the checks open to allow water to move through the valve. In some cases, the performance of an n-Pattern can exceed an inline backflow preventer, especially if you consider the 90-degree fittings needed to bring an inline valve out of a pit.
Rise above ground
Ready to remove your old below-grade backflow preventer? You can connect the n-Pattern setter to the existing pipe system along with any necessary additional straight pipe down in the pit to start. No 90-degree fittings are needed for less fuss and leak potential. The vertical risers align perfectly within the setter, and the n-Pattern valve will drop in and install with ease.
The crossbar support on an n-Pattern setter keeps the pipes underground from moving, so don’t worry about damage. Once the new n-Pattern is installed, the previous pit or vault can be backfilled. Now, you have valuable real estate back. In the end, you’ll be above ground and above the pitfalls.
Ease your installation and concern.