Selecting a Submetering System Part One: Meter Factors to Consider

When we speak to property owners and managers who are shopping for a water submetering system, many times the conversation comes around to a few overlooked or unknown details which can make or break the success of project; the Meters and the Read System.

The two primary components to a submetering system are the Meters and the Read System. The meter is the component installed in-line to actually measure consumption, while the Read System is the supplemental component installed to communicate the meter readings back to an accessible location, or in most cases, back to a central computer/gateway to be accessed from a location offsite.

For Part One of our series, we will review the many factors to consider when it comes to selecting the right meter, and help detail some questions which that help you make an informed decision.

Line Size

Line size will typically dictate which meter you install. A ¾” line will typically require a ¾” meter, and a 1” line, a 1” meter and so on.

Flow

This refers to the amount of flow a meter can handle, expressed in gallons per minute (gpm). The meter size can have an impact on head loss and end user pressure, but normally this is not an issue for residential meters. If there are concerns, most meters include a head loss chart similar to the one shown below.

Accuracy

It’s important to review the accuracy curve of a meter as well to ensure the meter is accurate at expected flow rates. For example, in commercial applications you might see a fairly large meter, say 1.5”, on a 1.5” line to serve a restaurant. If at some point down the road, a different business that uses much less water moves into the same space, and the 1.5” water meter is still installed, it will work, but you might experience accuracy problems.

The 1.5” meter has a larger range to accommodate higher flows of water, but will likely have a lower low-flow accuracy, because the meter was designed for higher flows. For example, I selected two commonly used meters with good reputation for accuracy and show the difference in low flow accuracy below:

Flow Rates at nominal operating ranges (+/- 1.5% accuracy)

As you can see, the smaller meter keeps its accuracy (+-1.5%) down to 1 gpm, while the larger meter keeps the same accuracy down to 5 gpm. This could mean inaccurate meter readings for a business with low volumes of water consumption, causing revenue loss which adds up over time. In addition, small leaks can be more difficult to catch with oversized meters, as accuracy drops at extremely low flow rates and this is exacerbated for larger meters which aren’t intended to detect such low flows.

Meter Location

Meter location is critical when selecting which meter is right for your application. Typically meters are installed near or directly after the primary shut off valve for the unit to ensure all water is captured prior to pipes splitting off. If this meter location is outdoors, it greatly impacts your meter selection as many meters are rated for indoor use only. Water meters going outdoors need to be sealed and meet IP68 standards in order to withstand outdoor elements such as water and dust.

In addition, certain meters can only be installed on horizontal or vertical lines due to accuracy limitations and certain certifications, and the vast majority of meters cannot be installed upside down. One great solution for a mix-bag of pipe orientations is to select a meter such as the Flexible Axis Meter (FAM), which offers 360 degrees of ration for the register, so that the register is always facing up, in the most accurate read position.

Water Temperature

Most water meters are designed to serve cold water applications, so if you are looking for a water meter which can handle hot water (for example on central boiler hot water situations), you’ll want to check the meter spec’s to ensure the meter can handle hot water temperatures. For example, the Next Century Hot Water meter meter can handle temperatures up to 194℉.

Space Constraints

It is important to consider space constraints when considering which meter to purchase. For example, if the meter is being installed in a hot water heater closet, with plenty of space, there is no need to purchase a smaller sized meter. However, if your meter is going inside access panels or another tight configuration, you might want to consider a meter with a shorter lay length and height profile. This information is readily available on most spec sheets.

Many residential ¾” water meters are 7.5” long, but shorter and longer meters are available, depending on the plumbing needs. This item becomes even more important if you are planning to replace your existing water meter with a new water meter. If this is the case, you’ll want to purchase a new meter with the same dimensions as the old meter to avoid potential re-plumbing costs.

Regulatory Concerns

Certain areas have regulations regarding which meters can be installed. California, for example, requires NTEP or State Type approval for any meter being installed in a residential or commercial application (click here to search for NTEP certificate). The meters must go through a series of accuracy/volume tests and meet other qualifying factors before obtaining the proper certification to be installed and used for revenue billing purposes.

In addition, all meters must go through County Weights and Measures testing and be sealed by the county prior to installation. Only meters of a certain quality will succeed in this testing, and failed meters can cause major headaches in construction timelines. Some states such as Massachusetts, have a similar approval lists, without the Weights and Measures County regulations.

All meters installed for potable water in the United States must also meet NSF/ANSI 61 requirements for safe water. It’s important to make sure you are buying from a reputable dealer and ask plenty of questions if you are concerned about regulatory issues.

Output Type

Output is a reference to the type of read system you will be installing to read the meters. Many meters are manually read, meaning a person physically walks up to the meter and takes the reading. In some cases, the meter location makes it prohibitive to access the meter for manual meter readings. In commercial applications, a meter located inside a tenant space, 15-20’ in the ceiling, is not practical to be read manually, and thus a remote reader would need to be installed and mounted in a location to be read conveniently.

In apartments, where meter readings are needed daily (mainly due to move in/out resident activity), and are located inside resident homes, it would not be a good idea to disrupt your resident each time a meter reading is needed. For this reason, wireless remote reading systems are typically installed, which read and transmit the reading of the meter to a central computer which uploads data throughout the day, so that meters are read daily with no resident intrusion or need for a meter reader. These systems are common in municipal water districts and most residential buildings, as manual meter reading has been phasing out for many years.

It is ideal to understand the type of remote read device you need to install on your meter prior to installing the meter, as meters have specific outputs (typically Pulse Output vs. Encoded Output), and you need to make sure the output of the meter matches the acceptable input allowed by your reading device.

If you have any questions about which meters are right for your project, please contact us and we will be happy to help. Stay tuned for Part Two, when we take an in-depth look into choosing the right read system for your submetering system!