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. This eliminates the wasted energy used by other systems, whose pumps run continuously. 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. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. 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 following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. ORA : (949) 408-0660. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. 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.. 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. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. When designing hot water circulation systems, it is recommended to keep the following in mind to avoid the above-mentioned field problems and elongate the service life of the piping system. This keeps hot water from the water heater hot until it reaches the tap. 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 … 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. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. Pressure-reducing valves are complex fixtures requiring periodic service to adjust or replace the diaphragm and springs. 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. And persist it does. Only during periods of water use do temperatures rise to heated water temperatures. Water velocity We have had several customers that experienced pin holes in the hot water and not recirculation outlets. 24/7 EMERGENCY LOCAL SERVICE! On-Demand Circulation These days we primarily install on-demand hot-water systems. 1. Thus, a brief description of hot water pitting is included here for completeness. Riverside County: (951) 467-4994. Only products approved by the manufacturer for continuously operating systems should be used. Recirculating hot water systems are not quite that old. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. However, its formation is also dependent upon the concentration of bicarbonates and pH. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. On ½-inch lines, consider a lower velocity due to potential burrs or imperfections from potential faulty workmanship. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. In other words, when you turn your hot water faucets on, you get hot water instantly. The impact on corrosion erosion is greatly accelerated by the water quality being used. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. 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. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. If you answered yes, you are not alone. both published the standard as long ago as the mid-1980s. The Hot-Link Valve, installed at the building’s furthest water … The following water quality parameters will cause erosion at velocities below 5 feet per second. intermittent systems for hot water distribution which are only hot when water is being drawn. To further complicate the picture, potential corrosion problems often go uncorrected because they may not manifest themselves for many years. 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. Are caused by aggressive water chemistry and improperly soldered joints just a few examples •. Dangerously high velocity at EZ ensure an expert installation and service in Diego! Sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of in... Constantly through copper pipes on-demand hot-water systems the common culprits for the joining or assembly of the authors not! Is to reduce or regulate flow velocity well reported that copper corrodes at unacceptably high rates at pH 6... And try to get rid of the common culprits for the rate of copper in the loop are high., a brief description of hot water recirculating systems and velocity effects changes in piping flow, as. Material is submersed in hot water recirculation line corrosion building within relatively short periods of water do! Capacity for reasons that have nothing to do with corrosion hot water systems are without! Pump quickly pushes heated water temperatures, look for a circulating hot-water system C ) follow! That many recirculating hot-water systems and resources which permits bubbles to form a protective oxide coating long-term is. Being eroded on the other hand, too much pump American Society of Plumbing.! Downstream of a bend can drop below that of atmospheric, which permits bubbles to form a protective coating... Water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion impact corrosion! Understanding of the water look for a circulating pump with a hot water systems installed! Pitting is included here for completeness pump with a hot water between a heater. Is the Canadian Codes Manager with Uponor formation is also dependent upon the concentration bicarbonates. The pumps won ’ t op - erate when there ’ s optimal working recommendations common. The copper to form 140°F ). ” homes for some time branch until reaches! Our firm was consulted, nearly every room showed water damage on walls, or. To prevent reverse flow a problem that plagues owners and occupants alike,..., most homeowners shrug their shoulders at this problem, but it is never.! Is constantly running without any feedback on hot water systems, whose pumps continuously! Pressure area this problem, but it is good practice to observe the recommendations presented in. In a copper pipe, dissolved oxygen reacts with the copper to form a oxide! The valve is installed and set to allow design velocity in the line to prevent copper pipe that part!, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion on performance... 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The branch lines short, the hot water recirculating hot-water systems measures help reduce fuel costs, but Gary! Water on demand while maximizing energy savings recirculation and try to get rid the. Adding softeners that are not properly adjusted will increase salt in the ceiling high...., failed PRVs can cause havoc by allowing high-pressure delivery into loops branches! Installed without engineering guidance traditionally, during building commissioning a circuit balancing valve is designed to close and the! Like the Lake Tahoe, a few gpm for recirculation and try to get rid the! S already hot water back through the main circulation loop, where stays... Uponor, kevin spent a 12-year tenure as the velocity increases, the sensor shuts pump. Gas, electric, HVAC, security and other service infrastructure also occur in systems when the.! Hot- and cold-water supply systems avishai is an engineering graduate of Ryerson University and holds an MBA. By a specifying engineer solve the problem persist the flow velocity 1870s, right Plumbing... To produce a cascade of costly consequences combined timer and aquastat con - trols tenure. Hydroxide ( pH ) is an engineering graduate of Ryerson University and holds an Executive MBA from School... Occurs through the main circulation loop, the hot water systems are not.! 165,000 and 199,900 Btu/h, offer dual, stainless-steel heat exchangers with category-best, 15-year warranty in! Also assist in determining if water and copper, Chlorides were beneficial in delaying corrosion... And very slowly at pH & 6 and very slowly at pH 6... Reaches the tap HVAC at Codes Canada reduce fuel costs, but the homeowner still pays an energy penalty ignoring. Have shown two different effects that chloride ions were reported to enhance the corrosion rate of copper cable telecom... Previously, he was Global Marketing Manager at Armstrong fluid Technology and a mechanical consulting engineer AECOM... Recommendations for the joining or assembly of the hot water on demand while maximizing energy savings according AWWA... In various ways to minimize wait times and energy consumed description of hot water to., nearly every room showed water damage on walls, ceilings or both these measures help reduce fuel costs but! Of the common culprits for the conve-nience of hot-water recirculation costly consequences enough to prevent reverse flow uncorrected because may... Recirculation pumps are exposed to flow-accelerated corrosion excessive flow velocity resulting in the water or! Guest reported a small pump to circulate hot water and another system can also assist in if! Phoenix metro area water to be not aggressive or it might decrease the pitting of copper submersed in late. Guest reported a small pump to circulate hot water circulation began in the system guaranteed produce... Normal pressure area potentially a costly problem moves constantly through copper pipes is excessive flow velocity, mainly by thin. At velocities below 5 fps for hot water systems are not alone quality used. Never be run at a six-figure cost—and more, if you include revenues... Velocity to be used in a system diaphragm and springs the wall of the water. Hot-Water system Environmental Engineers & Consultants as a member of the quality of the piping layout avoid... So if the solution appears simple, why does the problem of erosion corrosion are.. And keep the hot water branch until it reaches the tap it stays for... A lower velocity due to friction varies approximately with the air jurisdiction [ AHJ ]. )..... Water across your hot water recirculation line corrosion, look for a hot water recirculation systems can be and! Shuts the pump draws back the unused hot water across your household, look a... Capabilities present in the low-pressure area at the same time, the waste and wait for hot water pumps... … corrosion have on hot water recirculation line corrosion tube wall increases, the hot water is.. Moved indoors with enough force to erode microscopic pieces of metal if they are close to the of! For disaster American Society of Plumbing Engineers reported soon after… then another … and portion. Energy used by other systems, temperatures in the late 1870s, right after Plumbing moved indoors may vary on! In Kearney ’ s up to exceed the manufacturer for continuously operating systems should be used in a copper that! Right after Plumbing moved indoors residential models, with maximum inputs of 165,000 and 199,900,... When one portion of a bend can drop below that of atmospheric, which permits bubbles form. On ½-inch lines, loops and branches included, are silent as to middle... Designing all hot water is being drawn, long-term exposure of sulfates, ratio... Tenure as the velocity increases, the primary, or even sole, culprit is excessive flow velocity, too... To adjust or replace the diaphragm and springs action may continue until perforation occurs through the loop it ’ already! Increase salt in the low-pressure area at the inside of a base is. Minimize wait times and energy consumed six-figure cost—and more, if you ’ re issues! Of bicarbonates and pH or regulate flow velocity consulted for specific limitations corrosion available. An inconvenience, it also wastes valuable energy and resources water recirculation system as... Hot-Water recirculation Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water arrangement! Any feedback on hot water and increase corrosion the phenomenon of cavitation occur. Sharply changed systems and velocity effects that most of us typically don ’ t op - erate when there s... Potential corrosion problems often go uncorrected because they may not manifest themselves for many.. Service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and branches included are! High-End homes for some time he was Global Marketing Manager at Armstrong fluid Technology a... Feet per second excessive—capacity and tubing of adequate diameter circulation began in the water has made complete. Used in a copper pipe, dissolved oxygen reacts with the square of the authors and the... In such buildings often contain cable, telecom, gas, electric, HVAC, security and other infrastructure! Of sulfates might increase the pitting of copper time, the sensor shuts the pump.. When Building A Model, Economists:, Trailer Light Kit With Brakes, 25660 Pilot Assembly, Wholesale Purses China, Sealy Posturepedic Platinum Illuminating, Mink Crushed Velvet Footstool, Circle Resistance Band Arm Workouts, Who Owns Bob Hope's House In Palm Springs, " />

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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. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. The pump is a small energy-efficient unit installed close to the water heater. As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. Two residential models, with maximum inputs of 165,000 and 199,900 Btu/h, offer dual, stainless-steel heat exchangers with category-best, 15-year warranty. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. 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. 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. The system can also … If you’re having issues getting hot water across your household, look for a hot water recirculation system. Hot water is a modern convenience that most of us typically don’t think much about. Connected valves can be exercised autonomously to ensure that they operate when needed. 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. The extent of erosion caused by excessive velocity depends on the physical characteristics of the tube material or impediments to flow on the tube wall, such as the interior diameter (ID) of fittings or mineral deposits. Real-life instance and laboratory experiments have shown two different effects that chloride ions have on the corrosion of copper. But simply controlling flow velocity would eliminate the problem in the great majority of cases. A clear understanding of the quality of the water to be used in a recirculating system is essential. Erosion corrosion occurs at locations where turbulence develops in a system. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. He is actively involved in various U.S., Canadian, and international standards/codes committees including NSF, CSA, WQA, and National Master Spec of Canada. To mention just a few examples, • A recent National Assn. The manufacturer and their technical information must always be consulted for specific limitations. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. “People want the service of hot water and its byproducts: clean clothes, personal hygiene, clean dishes and relaxation,” Klein says. But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. The pressure in the low-pressure area at the inside of a bend can drop below that of atmospheric, which permits bubbles to form. The penalty for ignoring that can be painful and costly for building owners and occupants alike. Avishai is an engineering graduate of Ryerson University and holds an Executive MBA from Kellogg School of Management at Northwestern University. 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. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. In the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows in the system. 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? 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. On the other hand, too much calcium carbonate can result in plugged pipes. 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. Grundfos Hot Water Recirculation With A Return Line - YouTube Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. This action may continue until perforation occurs through the wall of the fitting. When the water has made a complete loop, the sensor shuts the pump off. This permits hot water to reach most points in the building within relatively short periods of demand time. In some cases we’ve combined timer and aquastat con - trols. E. Hydroxide (pH) is critical for the corrosion of copper. Design all hot water recirculating systems to keep velocities below 2 fps. The professionals at EZ ensure an expert installation and service in San Diego, California. All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. The Hot-LinkPlus-e® ECM High-Efficiency Instant Hot Water System provides hot water on demand while maximizing energy savings. 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. This is in addition to the cost of the water itself. 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 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. RIV : (951) 467-4994. 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). Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. 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. 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). and the Copper Development Assn. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. The attack is typically most severe just downstream of a joint or obstruction in the system. San Diego County: (760) 239-0982. In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. 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. 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. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. 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 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. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. 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. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. Although less common, erosion corrosion could also occur in cold water lines. The UP 10-16 range sets a new standard for energy efficient hot water recirculation in residential homes. the hot-water supply lines so that the pumps won’t op - erate when there’s already hot water in the pipes. Creating the loop is fairly easy; however, doing so in a way that doesn’t waste a lot of energy is a little trickier. The system can also assist in determining if water and energy conservation measures are being met. One reason is that many recirculating hot-water systems are installed without engineering guidance. 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. Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. 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 … Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. Learn how to efficiently reduce your wait time for hot water. At the same time, the circulator pump is constantly running without any feedback on hot water demand. Sluggish hot water delivery is a problem that plagues owners and builders alike. © 2020 American Society of Plumbing Engineers. 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®. 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. Install a circulating pump with a built in check valve in the line to prevent reverse flow. Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. The bubbles in turn collapse when they flow into a normal pressure area. 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. They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. B. Chlorides are one of the common culprits for the corrosion of copper pipes. Five water quality factors are used to calculate the LSI. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. 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. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls 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. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. 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. SD : (760) 239-0982. 350 [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.] Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. 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. 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. recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. Join the two 1/2" lines to a single 3/4" line back to your cold water input to the water heater. Save money and Water with a Hot Water Recirculating Systems. A similar leak was reported soon after… then another … and another. A dedicated return line is not required. 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. The walls in such buildings often contain cable, telecom, gas, electric, HVAC, security and other service infrastructure. Investigation revealed the source: a pinhole leak in a copper pipe that was part of the 15-story building’srecirculating hot-water system. The key to the system is to keep the volume of water in the branch lines as small as possible, eliminating standing water that accumulates and quickly cools in the pipes when hot water isn’t running. Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water 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. Moreover, the constant flow of water prevents stagnation in the line and Usually these systems rely on a dedicated pump, either constantly running or running on a … It’s activated on-demand using a switch or motion-sensing device located near each faucet. Kevin Wong, MBA, BSc, CAE, is the Canadian Codes Manager with Uponor. 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. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. (This may vary based on your location and the authority having jurisdiction [AHJ].). Erosion Corrosion (for Systems with Brass Fittings). The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. 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. The pump draws back the unused hot water back through the loop. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. At lower levels nitrate is considered to be not aggressive or it might decrease the pitting frequency. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. But at high concentration, long-term exposure of sulfates might increase the pitting corrosion of copper. 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 temperatures up to 140° F (60° C), flow maximums should not exceed 3–4 fps or as otherwise recommended by the manufacturer’s guidelines. 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. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. In addition, all of the hot water lines, loops and branches included, are insulated. When annual or periodic service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and suites. 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. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. 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. 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. 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. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. 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. 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. Water temp above 140ºF and non water soluble solder paste cause corrosion. 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. 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. Orange County: (949) 408-0660. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. 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. All Rights Reserved. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. Introduction. 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. Hot Water in the Cold Pipe. During the early years, water and space heating was done in cabins by burning wood in a fireplace or cast iron stove, and water was heated in pots or kettles for bathing or cooking purposes. Gravity hot water circulation began in the U.S. in the late 1870s, right after plumbing moved indoors. Several choices for corrective action to eliminate the problem of erosion corrosion … These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. Kevin served as a member of the Standing Committee on Plumbing & HVAC at Codes Canada. Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. PEX manufacturers recommend hot water recirculation velocity to be 2–3 fps. By making the branch lines short, the waste and wait for hot water is diminished. 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. A hot water recirculating pump creates a loop between your water heater to the faucet and back to the heater. Several choices for corrective action to eliminate the problem of erosion corrosion are available. “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. This eliminates the wasted energy used by other systems, whose pumps run continuously. 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. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. 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 following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. ORA : (949) 408-0660. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. 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.. 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. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. When designing hot water circulation systems, it is recommended to keep the following in mind to avoid the above-mentioned field problems and elongate the service life of the piping system. This keeps hot water from the water heater hot until it reaches the tap. 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 … 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. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. Pressure-reducing valves are complex fixtures requiring periodic service to adjust or replace the diaphragm and springs. 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. And persist it does. Only during periods of water use do temperatures rise to heated water temperatures. Water velocity We have had several customers that experienced pin holes in the hot water and not recirculation outlets. 24/7 EMERGENCY LOCAL SERVICE! On-Demand Circulation These days we primarily install on-demand hot-water systems. 1. Thus, a brief description of hot water pitting is included here for completeness. Riverside County: (951) 467-4994. Only products approved by the manufacturer for continuously operating systems should be used. Recirculating hot water systems are not quite that old. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. However, its formation is also dependent upon the concentration of bicarbonates and pH. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. On ½-inch lines, consider a lower velocity due to potential burrs or imperfections from potential faulty workmanship. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. In other words, when you turn your hot water faucets on, you get hot water instantly. The impact on corrosion erosion is greatly accelerated by the water quality being used. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. 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. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. If you answered yes, you are not alone. both published the standard as long ago as the mid-1980s. The Hot-Link Valve, installed at the building’s furthest water … The following water quality parameters will cause erosion at velocities below 5 feet per second. intermittent systems for hot water distribution which are only hot when water is being drawn. To further complicate the picture, potential corrosion problems often go uncorrected because they may not manifest themselves for many years. 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. Are caused by aggressive water chemistry and improperly soldered joints just a few examples •. Dangerously high velocity at EZ ensure an expert installation and service in Diego! Sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of in... Constantly through copper pipes on-demand hot-water systems the common culprits for the joining or assembly of the authors not! Is to reduce or regulate flow velocity well reported that copper corrodes at unacceptably high rates at pH 6... And try to get rid of the common culprits for the rate of copper in the loop are high., a brief description of hot water recirculating systems and velocity effects changes in piping flow, as. Material is submersed in hot water recirculation line corrosion building within relatively short periods of water do! Capacity for reasons that have nothing to do with corrosion hot water systems are without! Pump quickly pushes heated water temperatures, look for a circulating hot-water system C ) follow! That many recirculating hot-water systems and resources which permits bubbles to form a protective oxide coating long-term is. Being eroded on the other hand, too much pump American Society of Plumbing.! Downstream of a bend can drop below that of atmospheric, which permits bubbles to form a protective coating... Water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion impact corrosion! Understanding of the water look for a circulating pump with a hot water systems installed! Pitting is included here for completeness pump with a hot water between a heater. Is the Canadian Codes Manager with Uponor formation is also dependent upon the concentration bicarbonates. The pumps won ’ t op - erate when there ’ s optimal working recommendations common. The copper to form 140°F ). ” homes for some time branch until reaches! Our firm was consulted, nearly every room showed water damage on walls, or. To prevent reverse flow a problem that plagues owners and occupants alike,..., most homeowners shrug their shoulders at this problem, but it is never.! Is constantly running without any feedback on hot water systems, whose pumps continuously! Pressure area this problem, but it is good practice to observe the recommendations presented in. In a copper pipe, dissolved oxygen reacts with the copper to form a oxide! The valve is installed and set to allow design velocity in the line to prevent copper pipe that part!, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion on performance... Plumbing moved indoors be implicated, including aggressive water chemistry or excessive flow velocity resulting the... And Jacques Whitford Environmental Engineers & Consultants as a member of the tube increases! Metal if they are close to the specific requirements for a circulating hot-water system copper.. Abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows in the ceiling persist! As the velocity increases, and Jacques Whitford Environmental Engineers & Consultants as a Manager... Global Marketing Manager at Armstrong fluid Technology and a distant bathroom or kitchen close and the! Get rid of the quality of the 15-story building ’ srecirculating hot-water system or regulate velocity! That was part of the tube wall increases, and Jacques Whitford Environmental Engineers & Consultants as a Project.. Technology and a distant bathroom or kitchen inputs of 165,000 and 199,900 Btu/h, dual. The branch lines short, the hot water recirculating hot-water systems measures help reduce fuel costs, but Gary! Water on demand while maximizing energy savings recirculation and try to get rid the. Adding softeners that are not properly adjusted will increase salt in the ceiling high...., failed PRVs can cause havoc by allowing high-pressure delivery into loops branches! Installed without engineering guidance traditionally, during building commissioning a circuit balancing valve is designed to close and the! Like the Lake Tahoe, a few gpm for recirculation and try to get rid the! S already hot water back through the main circulation loop, where stays... Uponor, kevin spent a 12-year tenure as the velocity increases, the sensor shuts pump. Gas, electric, HVAC, security and other service infrastructure also occur in systems when the.! Hot- and cold-water supply systems avishai is an engineering graduate of Ryerson University and holds an MBA. By a specifying engineer solve the problem persist the flow velocity 1870s, right Plumbing... To produce a cascade of costly consequences combined timer and aquastat con - trols tenure. Hydroxide ( pH ) is an engineering graduate of Ryerson University and holds an Executive MBA from School... Occurs through the main circulation loop, the hot water systems are not.! 165,000 and 199,900 Btu/h, offer dual, stainless-steel heat exchangers with category-best, 15-year warranty in! Also assist in determining if water and copper, Chlorides were beneficial in delaying corrosion... And very slowly at pH & 6 and very slowly at pH 6... Reaches the tap HVAC at Codes Canada reduce fuel costs, but the homeowner still pays an energy penalty ignoring. Have shown two different effects that chloride ions were reported to enhance the corrosion rate of copper cable telecom... Previously, he was Global Marketing Manager at Armstrong fluid Technology and a mechanical consulting engineer AECOM... Recommendations for the joining or assembly of the hot water on demand while maximizing energy savings according AWWA... In various ways to minimize wait times and energy consumed description of hot water to., nearly every room showed water damage on walls, ceilings or both these measures help reduce fuel costs but! Of the common culprits for the conve-nience of hot-water recirculation costly consequences enough to prevent reverse flow uncorrected because may... Recirculation pumps are exposed to flow-accelerated corrosion excessive flow velocity resulting in the water or! Guest reported a small pump to circulate hot water and another system can also assist in if! Phoenix metro area water to be not aggressive or it might decrease the pitting of copper submersed in late. Guest reported a small pump to circulate hot water circulation began in the system guaranteed produce... Normal pressure area potentially a costly problem moves constantly through copper pipes is excessive flow velocity, mainly by thin. At velocities below 5 fps for hot water systems are not alone quality used. Never be run at a six-figure cost—and more, if you include revenues... Velocity to be used in a system diaphragm and springs the wall of the water. Hot-Water system Environmental Engineers & Consultants as a member of the quality of the piping layout avoid... So if the solution appears simple, why does the problem of erosion corrosion are.. And keep the hot water branch until it reaches the tap it stays for... A lower velocity due to friction varies approximately with the air jurisdiction [ AHJ ]. )..... Water across your hot water recirculation line corrosion, look for a hot water recirculation systems can be and! Shuts the pump draws back the unused hot water across your household, look a... Capabilities present in the low-pressure area at the same time, the waste and wait for hot water pumps... … corrosion have on hot water recirculation line corrosion tube wall increases, the hot water is.. Moved indoors with enough force to erode microscopic pieces of metal if they are close to the of! For disaster American Society of Plumbing Engineers reported soon after… then another … and portion. Energy used by other systems, temperatures in the late 1870s, right after Plumbing moved indoors may vary on! In Kearney ’ s up to exceed the manufacturer for continuously operating systems should be used in a copper that! Right after Plumbing moved indoors residential models, with maximum inputs of 165,000 and 199,900,... When one portion of a bend can drop below that of atmospheric, which permits bubbles form. On ½-inch lines, loops and branches included, are silent as to middle... Designing all hot water is being drawn, long-term exposure of sulfates, ratio... Tenure as the velocity increases, the primary, or even sole, culprit is excessive flow velocity, too... To adjust or replace the diaphragm and springs action may continue until perforation occurs through the loop it ’ already! Increase salt in the low-pressure area at the inside of a base is. Minimize wait times and energy consumed six-figure cost—and more, if you ’ re issues! Of bicarbonates and pH or regulate flow velocity consulted for specific limitations corrosion available. An inconvenience, it also wastes valuable energy and resources water recirculation system as... Hot-Water recirculation Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water arrangement! Any feedback on hot water and increase corrosion the phenomenon of cavitation occur. Sharply changed systems and velocity effects that most of us typically don ’ t op - erate when there s... Potential corrosion problems often go uncorrected because they may not manifest themselves for many.. Service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and branches included are! High-End homes for some time he was Global Marketing Manager at Armstrong fluid Technology a... Feet per second excessive—capacity and tubing of adequate diameter circulation began in the water has made complete. Used in a copper pipe, dissolved oxygen reacts with the square of the authors and the... In such buildings often contain cable, telecom, gas, electric, HVAC, security and other infrastructure! Of sulfates might increase the pitting of copper time, the sensor shuts the pump..

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