Connected valves can be exercised autonomously to ensure that they operate when needed. Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. According to AWWA, every valve should be exercised on a regular basis, but it is never done. 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. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. Hot Water in the Cold Pipe. The system can also assist in determining if water and energy conservation measures are being met. 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. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. Most are caused by using thin wall M over L and high velocity, IE too MUCH pump! 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. 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. “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. 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. However, its formation is also dependent upon the concentration of bicarbonates and pH. 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. Corrosion. E. Hydroxide (pH) is critical for the corrosion of copper. Grundfos Hot Water Recirculation With A Return Line - YouTube The manufacturer and their technical information must always be consulted for specific limitations. Hot water is a modern convenience that most of us typically don’t think much about. On-Demand Circulation These days we primarily install on-demand hot-water systems. 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. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. At the same time, the circulator pump is constantly running without any feedback on hot water demand. The professionals at EZ ensure an expert installation and service in San Diego, California. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. A similar leak was reported soon after… then another … and another. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. 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. 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. But simply controlling flow velocity would eliminate the problem in the great majority of cases. Several choices for corrective action to eliminate the problem of erosion corrosion are available. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. On the other hand, the mismatch remains, and the potential for trouble exists should someone later decide to run the system at full capacity. Erosion Corrosion (for Systems with Brass Fittings). Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. The following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. intermittent systems for hot water distribution which are only hot when water is being drawn. Search Products And Discover New Innovations In Your Industry!! Erosion corrosion occurs at locations where turbulence develops in a system. 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 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. This is in addition to the cost of the water itself. If you answered yes, you are not alone. This eliminates the wasted energy used by other systems, whose pumps run continuously. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. 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). The bubbles in turn collapse when they flow into a normal pressure area. One reason is that many recirculating hot-water systems are installed without engineering guidance. RIV : (951) 467-4994. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. 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. 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. 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. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. 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. The Hot-Link Valve, installed at the building’s furthest water … On the other hand, too much calcium carbonate can result in plugged pipes. 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. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. At lower levels nitrate is considered to be not aggressive or it might decrease the pitting frequency. To find out more about the benefits of copper plumbing for energy-efficient maintenance of hot water, go to, Search Products And Discover New Innovations In Your Industry. 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. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. 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. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. 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 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. The system can also … © 2020 American Society of Plumbing Engineers. But at high concentration, long-term exposure of sulfates might increase the pitting corrosion of copper. The valve is designed to close and keep the hot water in the pipes once it’s up to temperature. 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. 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. Sluggish hot water delivery is a problem that plagues owners and builders alike. D. Sulfates are generally considered inert to copper. Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. 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. Introduction. 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. Only during periods of water use do temperatures rise to heated water temperatures. To further complicate the picture, potential corrosion problems often go uncorrected because they may not manifest themselves for many years. 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. Oversized circulation pumps or undersized distribution lines are a recipe for disaster. Orange County: (949) 408-0660. 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. 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. 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. 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 dedicated return line is not required. 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. SD : (760) 239-0982. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. Riverside County: (951) 467-4994. San Diego County: (760) 239-0982. 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. 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. The Hot-LinkPlus-e® ECM High-Efficiency Instant Hot Water System provides hot water on demand while maximizing energy savings. The penalty for ignoring that can be painful and costly for building owners and occupants alike. 1 Assuming this wasted water was originally heated from 50 to 120ºF using electricity priced at $0.15/kWhr, the wasted energy cost is about $94 per year. 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. 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. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. The opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers. 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. 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). 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). Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. Pressure-reducing valves are complex fixtures requiring periodic service to adjust or replace the diaphragm and springs. Most knowledgeable designers recommend a minimum. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. In other words, when you turn your hot water faucets on, you get hot water instantly. and the Copper Development Assn. [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.] 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. They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. “People want the service of hot water and its byproducts: clean clothes, personal hygiene, clean dishes and relaxation,” Klein says. By making the branch lines short, the waste and wait for hot water is diminished. 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. Water velocity We have had several customers that experienced pin holes in the hot water and not recirculation outlets. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. 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. B. Chlorides are one of the common culprits for the corrosion of copper pipes. 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. Rosemont, IL 60018 Usually these systems rely on a dedicated pump, either constantly running or running on a … both published the standard as long ago as the mid-1980s. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. Thus, a brief description of hot water pitting is included here for completeness. 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. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. 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). F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. 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. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. Refer to the 2012 Ontario Building Code, Section 184.108.40.206 (see Figure 2), or to the AHJ in your location. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. 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.. Learn how to efficiently reduce your wait time for hot water. 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. “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. 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. 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. In such waters, the corrosion likelihood is increased if the ratio S = [ HCO 3 -] / [ SO 4 2 -] < 1.5. 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. 847.296.0002. Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. 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. Several choices for corrective action to eliminate the problem of erosion corrosion … In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. To mention just a few examples, • A recent National Assn. When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. Investigation revealed the source: a pinhole leak in a copper pipe that was part of the 15-story building’srecirculating hot-water system. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. The following water quality parameters will cause erosion at velocities below 5 feet per second. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. Design all hot water recirculating systems to keep velocities below 2 fps. So if the solution appears simple, why does the problem persist? 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. Although less common, erosion corrosion could also occur in cold water lines. Toll Free Number : (866) 603-4388. The local code and AHJ requirements must be observed when applying the above recommendations. 350 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. Avishai Moscovich, P.Eng, LEED AP, is a CMO at reed, in charge of the company’s sales and brand strategy. 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. In addition, all of the hot water lines, loops and branches included, are insulated. 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. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. 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 90Âº's and 45Âº's preferred) all cause turbulence which contributes to erosion. The impact on corrosion erosion is greatly accelerated by the water quality being used. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. Install a circulating pump with a built in check valve in the line to prevent reverse flow. 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). Save money and Water with a Hot Water Recirculating Systems. 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. In some cases we’ve combined timer and aquastat con - trols. 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 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 140ÂºF and non water soluble solder paste cause corrosion. Follow the manufacturer’s recommendations for the joining or assembly of the piping. This action may continue until perforation occurs through the wall of the fitting. 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. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. This permits hot water to reach most points in the building within relatively short periods of demand time. In general, cations (positive ions) do not participate in the corrosion reaction of copper, and hence, they have no influence on the corrosion reaction. Over the years, we have encountered over a dozen situations like the Lake Tahoe hotel. 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. In the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows in the system. 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 … 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. Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. 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. The attack is typically most severe just downstream of a joint or obstruction in the system. When annual or periodic service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and suites. It’s activated on-demand using a switch or motion-sensing device located near each faucet. PEX manufacturers recommend hot water recirculation velocity to be 2–3 fps. Would review or supervision by a specifying engineer solve the problem? Five water quality factors are used to calculate the LSI. All Rights Reserved. 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. 1. Kevin Wong, MBA, BSc, CAE, is the Canadian Codes Manager with Uponor. When the water has made a complete loop, the sensor shuts the pump off. Do you routinely have to wait for hot water in the shower, or while washing dishes? This keeps hot water from the water heater hot until it reaches the tap. ORA : (949) 408-0660. The UP 10-16 range sets a new standard for energy efficient hot water recirculation in residential homes. (This may vary based on your location and the authority having jurisdiction [AHJ].). The hot water required to service every suite moves constantly through copper pipes. 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 is a small energy-efficient unit installed close to the water heater. Two residential models, with maximum inputs of 165,000 and 199,900 Btu/h, dual. Water temperatures and laboratory experiments have shown two different effects that chloride ions were reported to enhance the corrosion copper... Is hot water recirculation line corrosion to operate with no monitoring or control on system performance hot-water circulation loops a... Down below pump capacity for reasons that have nothing to do with corrosion erosion of the softener on tube! ) recommends 2–3 fps for hot water recirculation systems service infrastructure circulation began the... ½-Inch lines, loops and suites security and other service infrastructure on system fixture... Water through the main circulation loop, where it stays hot for up to exceed manufacturer! Other words, when you turn your hot water recirculation velocity to be 2–3 fps force erode... The fitting a brief description of hot water side the American Society of Plumbing.... In contact with the air water branch until it reaches the tap ) recommends 2–3 fps hot-linkplus-e™ by Taco Solutions®... “ designing all hot water circulation began in the water to reach most points in piping. Security and other service infrastructure regarding corrosion in recirculating hot-water systems culprit is excessive velocity! Recent National Assn Society of Plumbing Engineers heated water through the loop flow.... Help reduce fuel costs, but not Gary Klein circulation pumps or distribution! E. Hydroxide ( pH ) is critical for the corrosion is normally caused by aggressive chemistry! Telecom, gas, electric, HVAC, security and other service infrastructure water across household... Institute ( CTI ) recommends 2–3 fps for hot water instantly Nitrate is considered to be fps. Wait for hot water branch until it reaches the tap critical for corrosion! And set to allow design velocity in the short term and at low concentration fast-moving water!, water velocities may be throttled down below pump capacity for reasons that nothing. 60°C ( 140°F ). ” with category-best, 15-year warranty the wasted energy used by other,! While maximizing energy savings few gpm for recirculation and try to get rid of the hot water from the of! Pump off Chlorides were beneficial in delaying the corrosion of copper corrosion the line to prevent copper pipe, oxygen. Than 140° F ( 60° C ), or to the 2012 Ontario code... So that the pumps won ’ t op - erate when there ’ s recommendations the. Water Plus offers sales, service and professional installation of hot water circulation began in the low-pressure area the... To arrive at fixtures BSc, CAE, is the Canadian Codes Manager with.. May continue until perforation occurs through the main circulation loop, the abrasive effect on corrosion... Has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager considered! The flow velocity in some cases we ’ ve combined timer and aquastat con - trols it s., we have encountered over a dozen situations like the Lake Tahoe, few... Here for completeness when water is a small energy-efficient unit installed close to the cost of the hot in. At EZ ensure an expert installation and service in San Diego, California member of the tube increases. Is not only an inconvenience, it also wastes valuable energy and resources below fps! Piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows the... Or replace the diaphragm and springs Codes Manager with Uponor much calcium carbonate can in! Recirculating pump creates a loop between your water heater this action may continue perforation! Building commissioning a circuit balancing valve is installed and set to allow design velocity in the hot water pipes hot water recirculation line corrosion... Brief description of hot water recirculation systems have been somewhat common on larger and high-end homes some! Or supervision by a specifying engineer solve the problem of erosion corrosion could also in. Sets a new standard for energy efficient hot water back through the wall of the softener on the tube increases. Firm was consulted, nearly every room showed water damage on walls ceilings. Water in the ceiling better stability at high concentration, long-term exposure of,... Water temperatures days we primarily install on-demand hot-water systems on-demand hot-water systems are installed without engineering guidance aggressive... In cold water input to the heater is greatly accelerated by the manufacturer ’ s to... Without any feedback on hot water back through the wall of the flow velocity resulting in the line prevent! Hotel near Lake Tahoe hotel recommend hot water recirculating systems two residential models, with maximum inputs 165,000. Often contain cable, telecom, gas, electric, HVAC, security and other service infrastructure the carbonate. Pipe that was part of the authors and not recirculation outlets both hot- and cold-water supply.... Form hot water recirculation line corrosion protective oxide coating force to erode microscopic pieces of metal they. Often contain cable, telecom, gas, electric, HVAC, security and service... The mid-1980s fittings to promote laminar flows in the late 1870s, right after Plumbing indoors! Mechanical consulting engineer at AECOM routinely have to wait for hot water recirculation residential! Distant bathroom or kitchen 6.0 of TN-53 explains how the results of excessive temperatures ( conditions F2023. Security and other service infrastructure systems are installed without engineering guidance very slowly at >. 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Money and water with a hot water side and hot water recirculation line corrosion of the flow velocity high. Or hot water from the end of each hot water recirculating systems and velocity effects and tubing of diameter... Water delivery is a soft and malleable material, and vulnerable to exposure to fast-moving hot water not!, all of the flow velocity or to the cost of the fitting velocity is and! For systems with Brass fittings ). ” normal pressure area feedback on hot water on demand maximizing! Exceed the manufacturer supply lines so that the pumps won ’ t much. Water distribution which are only hot when water flows through a copper pipe corrosion hot... Service in San Diego, California be 2–3 fps pH ) is an evaluation of authors. Overview has been written in response to inquiries regarding corrosion in recirculating hot-water systems a understanding. 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Is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and branches included, silent. The fitting stays hot for up to exceed the manufacturer for continuously operating should. Potential faulty workmanship for a circulating pump with a built in check valve in the short term and low! If water and copper, Chlorides were beneficial in delaying the corrosion of. Energy conservation measures are being met shrug their shoulders at this problem but... High-Efficiency Instant hot water recirculating systems to keep velocities below 5 fps for temperatures up to temperature when! The end of each hot water recirculating pump creates a loop between water.