Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. A dedicated return line is not required. Toll Free Number : (866) 603-4388. When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. The impact on corrosion erosion is greatly accelerated by the water quality being used. Continued corrosion causes thinning of the tube wall, which may start as a series of deep U-shaped pits and a general roughening of the surface, which in turn causes additional turbulence and accelerates the corrosive process. This action may continue until perforation occurs through the wall of the fitting. Normally, when not in use and flowing, the water in a hot water copper service line cools down to the ambient temperature of the household (70 to 80 °F). Save money and Water with a Hot Water Recirculating Systems. 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. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. Rosemont, IL  60018 If you’re having issues getting hot water across your household, look for a hot water recirculation system. In a fitting, the centrifugal force flowing around a short-bend radius at high velocity causes an increase in pressure at the outer portion of the bend and a resultant lowering of the pressure at the throat. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. 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. 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. 350 In addition, all of the hot water lines, loops and branches included, are insulated. 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. 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. The most important is to reduce or regulate flow velocity, mainly by using a pump of appropriate—not excessive—capacity and tubing of adequate diameter. 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. When the water has made a complete loop, the sensor shuts the pump off. But simply controlling flow velocity would eliminate the problem in the great majority of cases. Refer to the 2012 Ontario Building Code, Section 7.6.3.5 (see Figure 2), or to the AHJ in your location. Would review or supervision by a specifying engineer solve the problem? Typically, a recirculating pump is used to pump hot water from a water heater through the copper hot-water pipeline, at the same time returning water that has cooled from the hot-water lines back to the water heater to be reheated. On the other hand, too much calcium carbonate can result in plugged pipes. Turbulence can be caused by excessive velocity, sudden changes in direction, and flow obstacles such as restrictive fittings (i.e., with a lower ID than the pipe sizing). 24/7 EMERGENCY LOCAL SERVICE! The professionals at EZ ensure an expert installation and service in San Diego, California. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. According to AWWA, every valve should be exercised on a regular basis, but it is never done. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Thus, a brief description of hot water pitting is included here for completeness. 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. A similar leak was reported soon after… then another … and another. Follow the manufacturer’s recommendations for the joining or assembly of the piping. As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. Erosion corrosion occurs at locations where turbulence develops in a system. This eliminates the wasted energy used by other systems, whose pumps run continuously. Typically, a recirculating pump is used to pump hot water from a water heater through the copper hot-water pipeline, at the same time returning water that has cooled from the hot-water lines back to the water heater to be reheated. 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. Sluggish hot water delivery is a problem that plagues owners and builders alike. In some multi-unit residential buildings, as part of the domestic distribution system, water is pressurized in a high-pressure system and then stepped down in the zones mechanical rooms through an arrangement that includes pressure-reducing valves (PRV), a circulator pump, and a heat exchanger to a low-pressure delivery system to individual suites (see Figure 1). The surface is most affected in areas where turbulence develops, such as below bends, elbows and tees, which is where the tell-tale pinholes are commonly found. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. Over the years, we have encountered over a dozen situations like the Lake Tahoe hotel. 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. 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. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. 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 local code and AHJ requirements must be observed when applying the above recommendations. In other words, when you turn your hot water faucets on, you get hot water instantly. 6400 Shafer Court, Ste. of Corrosion Engineers publication stated that “flow maximums should not exceed 3 to 4 fps for water >60°C”, • A “special report” from Hotel Online warns that “water velocities exceeding 4 fps” could be a “contributing factors” to corrosion, • A 2006 advisory from the Copper Development Assn. Although less common, erosion corrosion could also occur in cold water lines. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. You get all the water savings of a recirculation loop, with no more energy used than would be needed to feed faraway fixtures without the loop. On the low-pressure side we control the zone 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. This water saving device can save the average family of 4 up to 16,000 gallons of water yearly, plus it gives you the convenience of having hot water available when you want it within several seconds. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. Avishai Moscovich, P.Eng, LEED AP, is a CMO at reed, in charge of the company’s sales and brand strategy. This creates a differential of the amount of oxygen in contact with the material's surface above and below the waterline and results in a corrosive reaction. While this can also happen in non-metal fittings, the effects are much less dramatic due to the elasticity/plasticity of the materials and that ability to absorb some of the energetics of cavitation effects. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. A typical hot water recirculating system in a commercial building consists of a piping loop in which hot water, from hot water tanks or boilers, is kept circulating by one or more pumps. The following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. In some cases we’ve combined timer and aquastat con - trols. It combines a 006e3™ ECM hot water circulator with Taco’s Hot-Link® Valve and Smart Plug Instant Hot Water Control® in one easily-installed package. When annual or periodic service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and suites. In the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows in the system. To repeat: these systems should be so designed that hot water temperatures generally do not exceed 140°F (60°C), depending on local codes requirements, and flow velocity is no greater than 3 fps. 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. Several choices for corrective action to eliminate the problem of erosion corrosion … Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. Taco’s Hot-LinkPlus-e instant hot water system combines the easy-to-install Hot-Link® Valve with the 006e3® hot water circulation pump and the award winning SmartPlug Instant Hot Water Control®. for hot water to appear at points of use while subsequently reducing wasted water going down the drain are recirculation systems, electric hot water temperature maintenance systems, and point of use heaters. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. Delivery of high 200-psi pressure in a low-pressure-rated pipe increases the risk for ruptures, water hammer, and/or temperature imbalances that can potentially lead to scalding. This can mask the underlying design vulnerability, since the system may never be run at a dangerously high velocity. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. Domestic Hot Water Recirculation Systems Application, Selection & Installation Guide Effective Date: 01/31/06 Printed in USA Water Circulation Pumps & Circulators ©Taco Catalog # 100-41 Supersedes: New Use at 40%, Centered (In place of “Do it Once. The most important constituents are the following: A. Bicarbonates are believed to have beneficial effects on copper corrosion because they can form a calcium carbonate film on the surfaces of the pipe and protect it from corrosive water. Introduction. Search Products And Discover New Innovations In Your Industry!! (This may vary based on your location and the authority having jurisdiction [AHJ].). Kevin is an environmental sciences graduate from York University and holds an MBA from the Schulich School of Business, with various certificates from University of Toronto and the Canadian Society of Association Executives. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. The manufacturer and their technical information must always be consulted for specific limitations. recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. This is in addition to the cost of the water itself. Hot water is a modern convenience that most of us typically don’t think much about. Water temp above 140ºF and non water soluble solder paste cause corrosion. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. The pump is a small energy-efficient unit installed close to the water heater. 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. The pump is easily controlled with a simple user interface and multiple pump settings allow you to customize pump operation to meet your needs while maximizing heater efficiency. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. 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. If you answered yes, you are not alone. On the other hand, the mismatch remains, and the potential for trouble exists should someone later decide to run the system at full capacity. When the temperature of the water at the furthest fixture is within a few degrees of the hot setpoint, the pump stops (because at this point, the hot water lines are filled with hot or nearly hot water). Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. The walls in such buildings often contain cable, telecom, gas, electric, HVAC, security and other service infrastructure. The penalty for ignoring that can be painful and costly for building owners and occupants alike. Their purpose is to reduce the amount of time you have to wait for hot water to reach a faucet, a goal accomplished by pumping hot water through the supply line before you turn the faucet on. 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. The bubbles in turn collapse when they flow into a normal pressure area. The following water quality parameters will cause erosion at velocities below 5 feet per second. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. ORA : (949) 408-0660. The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. The UP 10-16 range sets a new standard for energy efficient hot water recirculation in residential homes. The opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers. 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. To mention just a few examples, • A recent National Assn. Investigation revealed the source: a pinhole leak in a copper pipe that was part of the 15-story building’srecirculating hot-water system. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. With hot water circulating constantly in well-insulated pipes, users—even those far from the water heater—never have to wait for the water to get hot. 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. One reason is that many recirculating hot-water systems are installed without engineering guidance. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. Install a circulating pump with a built in check valve in the line to prevent reverse flow. Erosion Corrosion (for Systems with Brass Fittings). Kevin served as a member of the Standing Committee on Plumbing & HVAC at Codes Canada. The recirculation pump then circulates the hot water throughout the entire building so every fixture has hot water within about 5 seconds of opening the faucet. Recirculating hot water systems, designed to provide nearly instantaneous hot water at the tap, have become a common amenity, especially in hotels and large high-end multifamily residential complexes, where a high level of convenience is expected. 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. But at high concentration, long-term exposure of sulfates might increase the pitting corrosion of copper. both published the standard as long ago as the mid-1980s. On-Demand Circulation These days we primarily install on-demand hot-water systems. In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. 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. Grundfos Hot Water Recirculation With A Return Line - YouTube They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. By making the branch lines short, the waste and wait for hot water is diminished. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. Investigations of PEX tube and fitting samples taken from hot water recirculating systems have identified several factors that contributed to the factors leading to damage and failure of the system: System performance where temperature, pressure, and flow are maintained per design conditions and meet manufacturer recommendations will promote laminar flow and ensure adequate service life of the piping system. B. Chlorides are one of the common culprits for the corrosion of copper pipes. 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.. “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. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. Kevin Wong, MBA, BSc, CAE, is the Canadian Codes Manager with Uponor. Moreover, the constant flow of water prevents stagnation in the line and The hot water required to service every suite moves constantly through copper pipes. The system can also assist in determining if water and energy conservation measures are being met. Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. Design all hot water recirculating systems to keep velocities below 2 fps. The attack is typically most severe just downstream of a joint or obstruction in the system. Other precautions also should be observed, such as reducing the number of joints if possible (to minimize turbulent flow), avoiding abrupt changes in direction wherever possible, and assuring quality work (e.g., taking care that burrs are removed from tube ends before joining, joints are soldered according to ASTM standards, etc.). Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. The present author has also observed this type of hot water pitting in recirculating hot water systems (Nicholas, 2014), which shows that corrosion/erosion is not the only degradation mechanism that can occur in RHWS, although the latter is the most prevalent. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. RIV : (951) 467-4994. 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. Real-life instance and laboratory experiments have shown two different effects that chloride ions have on the corrosion of copper. The answer is, “Yes, but…” The “but” refers to the fact that relatively few engineers understand that flow velocity in these systems should, in my opinion, always be kept below 3 feet per second (fps), even though the American Water Works Assn. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. 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. Corrosion. Gravity hot water circulation began in the U.S. in the late 1870s, right after plumbing moved indoors. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls 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. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. Usually these systems rely on a dedicated pump, either constantly running or running on a … All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. 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. Water-line corrosion (WLC) is a typical localized corrosion phenomenon believed to derive from the formation of differential aeration cells (DACs) .The area above the water level is highly oxygenated and acts as a cathode while the part … With hot water circulating constantly in well-insulated pipes, users—even those far from the water heater—never have to wait for the water to get hot. In an effort to ensure instantaneous delivery of hot water, an oversized pump has been installed, with the result that the pipes are literally eroded away by their own contents. intermittent systems for hot water distribution which are only hot when water is being drawn. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. A hot water recirculating pump creates a loop between your water heater to the faucet and back to the heater. While the water is typically deemed potable and thus clean, there are still instances where debris, sediment, and other elements can scour the inside surfaces of any piping material, and excessive velocity increases the risk of erosion corrosion in these cases. This keeps hot water from the water heater hot until it reaches the tap. This turbulence interferes with the normal protective film formation on the inside of the tube or fitting and also erodes the brass surface at that point. [Note: CDA recommendations are that the flow velocity not exceed 4 to 5 fps, and suggests that 4 fps would be a more appropriate figure here.] Unreamed tube ends, excessive flow rate (due to high water pressure, an over sized pump, or too small a return line [3/4" preferred]) and sharp changes in direction on the return line (long turn 90º's and 45º's preferred) all cause turbulence which contributes to erosion. Learn how to efficiently reduce your wait time for hot water. 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. FOUNTAIN VALLEY, CALIF. (JANUARY 12, 2019) — New from Noritz America, the NRCR Residential Condensing Tankless Water Heater Series uses a fully integrated pump to keep hot water close to even the farthest outlet in the … Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. However, its formation is also dependent upon the concentration of bicarbonates and pH. But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. The pump draws back the unused hot water back through the loop. Available in configurations for both new and existing installations, the system costs around $500 to install and reduces water waste by up to 95%, cutting operational costs to a bare minimum. Only during periods of water use do temperatures rise to heated water temperatures. So if the solution appears simple, why does the problem persist? D. Sulfates are generally considered inert to copper. In America, a typical single-family home wastes about 10 gallons of water a day—and that adds up to $11 billion per year in heating and waste-water treatment down the drain. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. Do you routinely have to wait for hot water in the shower, or while washing dishes? At lower levels nitrate is considered to be not aggressive or it might decrease the pitting frequency. assures readers that “corrosion can be mitigated if systems are designed so that velocities do not exceed 4 to 5 fps (1.2 to 1.5 mps) in circulating systems”, • The Canadian Copper & Brass Development Assn. The Hot-Link Valve, installed at the building’s furthest water … the hot-water supply lines so that the pumps won’t op - erate when there’s already hot water in the pipes. The issue rarely shows up clearly because many of the overbuilt systems are routinely operated at less than their full design capacity for a variety of reasons, such as low initial occupancies or low demand for hot water. E. Hydroxide (pH) is critical for the corrosion of copper. When one portion of a joint or obstruction in the shower, or while washing dishes ’! Quality parameters will cause erosion at velocities below 2 fps and fittings for the conve-nience hot-water... 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