IoT technologies can be added to advance plumbing designs and provide owners and operators with connectivity to the domestic water systems.
by Adam Bartman and Avishai Moscovich, P.Eng, LEED AP
As we discussed in Part 1 of this article, mid-market-type buildings typically don’t have access to a building automation system (BAS) or any type of visibility for their domestic water systems. Let’s follow the path of water in a plumbing system as it enters a typical two-zone, multi-unit residential building (see Figure 6) and see where current IoT technologies can be added to advance plumbing designs and provide owners and operators with connectivity to the domestic water systems.
Basement Mechanical Room
We start in the basement mechanical room (see Figure 7), where we typically find a revenue-grade water meter allowing the local water utility company to calculate consumption and bill the property. This is immediately followed by a code-required backflow prevention device and often a strainer or a filtration system to remove fine particles from the water supply. The next system inline is a boosting pump package that supplies the cold water to the building at a particular pressure.
Using IoT technology we can add visibility into the system performance by applying sensory fixtures to the existing layout without any changes to the system layout, connecting the existing water meter to the cloud to record water usage and flow rate data and allowing the operators to see real-time conditions remotely. By adding real-time pressure sensors across the water filtration system, you can understand when it is due for media replacement, if the pressure drops, or if the filter hasn’t gone into an automatic wash cycle. Adding an actuated valve following the backflow prevention device also allows easy remote water shutoff in case of emergency. Lastly, you also can provide a connectivity platform for new booster pumps, which are typically equipped with VFD motors and sophisticated operation logic but lack the connectivity option to alert the operator in case of a problem.
Pressure Reducing Valve (PRV) at Zones Distribution
As we move along the domestic distribution system, the water pressure increases, and then through an arrangement that includes pressure reducing valves (PRV), a circulator pump, and a heat exchanger, it is stepped down in the mechanical room zones to a low-pressure delivery system to individual suites. For example, within each zone is a group of 10 floors, so we will have hot and cold water supply high pressure stepped down through a PRV from 200 pounds per square inch (psi) to an adequate deliverable low-pressure side of 70 psi. Furthermore, on the low-pressure side we control the zone’s hot water conditions with a recirculating pump, a heat exchanger, and a balancing valve to collect all of the hot water and put it back into the hot water supply.
Typically, this complex arrangement is left to operate with no connectivity or visibility on system or fixture performance. However, with current IoT technology, a lot of value can be created for operators and owners. For instance, replacing manual valves with actuated connected valves on the hot, cold, and recirculating lines gives the operator the ability to remotely shut down and contain a single zone in case of an emergency instead of shutting down water to the whole building. According to the American Water Works Association (AWWA), every valve should be exercised on a regular basis, but this is rarely done. Connected valves, which are not modulating on a regular basis like in HVAC systems, can be exercised autonomously to ensure they will operate when needed.
The pressure reducing valve is a complex fixture, requiring annual service to replace the diaphragm and springs. When annual service is not maintained, a failed PRV can cause havoc by allowing high-pressure delivery into suites. The delivery of high 200-psi pressure in a low-pressure-rated pipe increases the risk for ruptures, water hammer, and temperature imbalances that might lead to scalding. By replacing the manual pressure gauges with a real-time connected pressure sensor, we can now understand the operation of a PRV and, most importantly, send an alert to the operator in case a PRV fails and the outlet pressure increases above the design threshold.
The third IoT technology to apply would be on the domestic hot water recirculation within a zone (see Figure 8). Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. Often, within a couple of years you will find that the balancing valve has been moved, is not in the proper set position anymore, and there is no indication on the flow or water velocity in the system. At the same time, the circulator pump is constantly running without any feedback on hot water demand. This unmonitored operation where pressure, temperature, and velocity often exceed the manufacturer’s optimal working recommendations leads to early failure of copper and PEX piping systems. With current IoT technology, by installing a connected flow meter and temperature and pressure sensors in lieu of manual gauges, you can maintain the recirculation flow rate at the optimal position and extend pipe life. Furthermore, cloud-connected IoT applications can save energy by adding night setback sequences at low demand periods via throttling down the hot water recirculation flow to a minimum.
Risers and Circuit Balancing
Next, let’s look at the hot and cold water risers of the domestic plumbing system (see Figure 9). The hot water risers will end at a recirculation header with a circuit balancing valve. The day-to-day operations in a multi-unit residential building often involve plumbing service in suites. When a plumber shows up and needs to repair service in one suite, they often need to shut down water to the whole building. Applying affordable and low-cost IoT technology by replacing the traditional manual riser valves with a connected valve has a few benefits such as automated circuit balancing and riser shutdown in case of a service call. Also, as mentioned above, autonomous valve exercising ensures that valves operate as needed and essentially streamlines plumbing system operation and service.
In multi-unit residential buildings, toilets that malfunction and leak water often go undetected and become the main cause of water waste. Most residents are either not aware of the water leaking or don’t complain about it. This makes the water bill a variable, uncontrollable cost. Looking at the bulk water bill does not provide specific information on water use, and it does not identify water waste. On the other hand, sending a superintendent to check all units has become increasingly difficult in today’s environment. When you combine these factors with the rapid increase of water rates in many cities, this becomes a prevalent problem for building owners. Here as well, IoT technology, specifically real-time cold water riser monitoring, can provide real-time data and identify water waste.
Hot Water Management
Domestic hot water storage tanks often located in the boiler will supply the hot water to suites via mixing valves (see Figure 10). Traditionally, both storage tanks and mixing valves are manually set and lack any type of real-time feedback on temperature settings. Now more than ever, with post-COVID-19 building reopening, there is a need for real-time monitoring of hot water temperatures to prevent Legionella and other bacteria in potable water. Adding connected temperature sensors to mixing valves and an actuated valve on the hot water recirculation line allows real-time water management in mid-market buildings. In addition, cloud platforms can easily be utilized to incorporate all aspects of compliance with ANSI/ASHRAE Standard 188-2018, Legionellosis: Risk Management for Building Water Systems to manage the risk of Legionellosis in building domestic water systems, including testing, monitoring, control, and administration.
Summary
In summary, a large market segment is in need of advanced building plumbing systems to deal with older infrastructure. When the control and monitoring of plumbing systems have long been ignored, you can add much value by capturing real-time data with simple and affordable IoT cloud-enabled technology.
Adam Bartman is a second generation Red Seal Endorsed plumber from Toronto, Ontario. He began his career working alongside his father every summer from age 14-18. Utilizing his plumbing experience and passion to technology, he co-founded reed to bring plumbing system online helping landlords, and service providers manage water at commercial properties.
Avishai Moscovich P.Eng. LEED AP is a CMO at reed, in charge of the company’s sales and brand strategy. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. Avishai is an engineering graduate of Ryerson University and holds an Executive MBA from Kellogg School of Management at Northwestern University.
The opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers.
