Replacing manual valves with actuated connected valves on the hot, cold, and recirculating lines allows the operator to remotely shut down and contain a single zone in case of an emergency instead of shutting down water to the whole building. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. Often, within a couple years you will find that balancing valve has been moved and is not in the proper set position anymore, and there is no indication on the flow or water velocity in the system. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls Excessive velocity in a hot water recirculating system is typically the result of using an oversized pump, undersized distribution lines, or system creep that, along with lack of maintenance, leads to excessive velocities. Often, the most commonly affected areas are elbows, tees, and bends where the pipe walls can become so thin to the extent of eventually rupturing. Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. So if the solution appears simple, why does the problem persist? All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. The system uses a circulation pump that supplies hot water on demand through a loop of copper plumbing tube situated no more than 10 feet away from any fixture where hot water is used. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. Unfortunately, these systems can be vulnerable to flow-accelerated corrosion, sometimes called erosion corrosion, which in turn can quickly mushroom into a costly and disruptive problem. If you turn on the cold water and get hit with hot water instead, you may actually have a problem with the bypass valve that’s a part of your hot water recirculation system, rather than the pump itself. Water temp above 140ºF and non water soluble solder paste cause corrosion. For temperatures up to 140° F (60° C), flow maximums should not exceed 3–4 fps or as otherwise recommended by the manufacturer’s guidelines. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. Erosion corrosion is readily identified from the characteristic appearance of the damaged surface (tear-dropped or leaf-shaped impact craters and scouring in some areas). In general, cations (positive ions) do not participate in the corrosion reaction of copper, and hence, they have no influence on the corrosion reaction. The penalty for ignoring that can be painful and costly for building owners and occupants alike. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. Hot water, especially in a pumped circulation system, is required to maintain lower velocities because of hot water's greater tendency to release oxygen bubbles, which increases with velocity, causing acceleration in corrosion. And persist it does. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. E. Hydroxide (pH) is critical for the corrosion of copper. Introduction. Several choices for corrective action to eliminate the problem of erosion corrosion … Connected valves can be exercised autonomously to ensure that they operate when needed. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. Options include a bypass around the pump to reduce its effective output, a smaller-capacity pump, or a throttling/balancing valve downstream of the pump to restrict the flow, in addition to larger tube sizes in the areas affected. This action may continue until perforation occurs through the wall of the fitting. 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. Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. The best hot water recirculating pump saves you on energy and water cost, cuts down the workload on your water heater, and overall delivers hot water fast to every faucet in the house.. In fact, he helped refine the system so that now as little as one cup of water is wasted while waiting for the hot water to arrive. Moreover, the constant flow of water prevents stagnation in the line and In addition to reducing the flow, it is good practice to limit domestic hot water to an optimal temperature of 140° F (60° C), since increasing the temperature of potable water can substantially change its corrosive effects on materials. “Corrosion in Hot Water Recirculating Systems and Velocity Effects”, GF Piping Systems Announces Presentation at “DCD>Keeping IT Cool” Virtual Conference →, Water velocities exceeding 2 feet per second (fps), Undersized distribution lines, creating higher apparent velocities, Oversized circulating pumps with no bypass, creating excessive velocities at times of low demand or during the startup/commissioning phase, Multiple and/or abrupt changes in direction (i.e., short 90-degree fittings in the system decreasing the energetic of the overall system), Failure to flush out debris inside the tube, Improper use of throttling valves for system balancing, Lack of maintenance, monitoring, and control. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. Thus, a brief description of hot water pitting is included here for completeness. Erosion corrosion occurs at locations where turbulence develops in a system. For example, per the Ontario Building Code, with each zone is a group of eight to 12 floors, and 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 80 psi. By replacing 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 Hot-LinkPlus-e® ECM High-Efficiency Instant Hot Water System provides hot water on demand while maximizing energy savings. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. However, if you have ever had to wait several minutes for the water coming out of the faucet to heat up, you may be interested in learning more about hot water recirculating pumps. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. By installing a connected flow meter and temperature and pressure sensors in lieu of the manual gauges, you can maintain the recirculation flow rate at optimal position and extend pipe life. Real-life instance and laboratory experiments have shown two different effects that chloride ions have on the corrosion of copper. But the flowing hot water is constantly trying to dissolve or erode the protective oxide film, and the higher the velocity, the greater the abrasive effect. Plastics Pipe Institute (PPI) test TN-53 recommends following the manufacturer’s recommend maximum velocities in situations outside of typical hot water usage, such as greater than 140° F (60° C) or non-typical applications like constant velocity. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. Would review or supervision by a specifying engineer solve the problem? In his job as an energy specialist with the California Energy Commission, Klein learned of a plumbing system that delivers hot water without wasting nearly as much water. A hot water recirculating pump creates a loop between your water heater to the faucet and back to the heater. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. The bubbles in turn collapse when they flow into a normal pressure area. The system can also assist in determining if water and energy conservation measures are being met. The Hot-Link Valve, installed at the building’s furthest water … This is based on the water chemistry of the inlet water from the distribution system or well supply, the efficacy of the water treatment or filtration level, and the resulting corrosiveness of the water itself. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. By Jose L. Villalobos, P.E., Founder and CEOV&A Consulting Engineers, Oakland, Calif. Understanding the changes to NFPA 70-2020, Designing flexible, safe labs: Electrical, power and lighting, Designing flexible, safe labs: Fire and life safety, Circular economy ideas are leading to better real estate investments, Designing flexible, safe labs: HVAC and plumbing, Top 5 Consulting-Specifying Engineer articles: December 11-17, 2020. The article will discuss factors that may affect the service life of PEX tube and fittings in such systems with specific recommendations for both new and existing multi-unit residential buildings. For example, at a 400-unit North Bay Area condominium complex, corrosion damage caused massive dislocation and other inconveniences as well as extensive, costly repairs and reconstruction. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. Toll Free Number : (866) 603-4388. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. The manufacturer and their technical information must always be consulted for specific limitations. RIV : (951) 467-4994. 24/7 EMERGENCY LOCAL SERVICE! Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. Although it’s not unusual for plumbers to install circulation pumps to improve home hot-water circulation, this system is unique in that the pump runs only when hot water is needed. 847.296.0002. When the water has made a complete loop, the sensor shuts the pump off. Regarding maintenance, monitoring and control,  current market Internet of Things (IoT) technologies can easily add visibility and control to hot water recirculation systems, in both new construction and retrofits. Erosion Corrosion (for Systems with Brass Fittings). Connected valves on the domestic hot water system, which are not modulating on a regular basis like in an HVAC system, can be exercised autonomously to ensure that they operate when needed. Flow-accelerated corrosion is a well-known and serious hazard in the electric power industry, where it damages boiler feed water systems, and National Regulatory Commission regulations include specific inspection procedures for monitoring and maintenance of erosion-corrosion/flow-accelerated-corrosion (EC/FAC) in nuclear plants. “People want the service of hot water and its byproducts: clean clothes, personal hygiene, clean dishes and relaxation,” Klein says. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. “And, they want it now.” Klein is a strong advocate of The Metlund Hot Water D’MAND System, developed and marketed by Larry Acker, President of Advanced Conservation Technology, Inc. Metlund Systems. 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