This eliminates the wasted energy used by other systems, whose pumps run continuously. Would review or supervision by a specifying engineer solve the problem? It’s activated on-demand using a switch or motion-sensing device located near each faucet. 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. The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. 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. Most knowledgeable designers recommend a minimum. “People want the service of hot water and its byproducts: clean clothes, personal hygiene, clean dishes and relaxation,” Klein says. 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. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. 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 … Usually these systems rely on a dedicated pump, either constantly running or running on a … RIV : (951) 467-4994. The UP 10-16 range sets a new standard for energy efficient hot water recirculation in residential homes. In such waters, the corrosion likelihood is increased if the ratio S = [ HCO 3 -] / [ SO 4 2 -] < 1.5. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. Most are caused by using thin wall M over L and high velocity, IE too MUCH pump! Water velocity We have had several customers that experienced pin holes in the hot water and not recirculation outlets. The system can also … 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. A dedicated return line is not required. Kevin served as a member of the Standing Committee on Plumbing & HVAC at Codes Canada. 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. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. Re: Pin hole leaks in copper pipes by hot water recirculating systems; Author: Big Ken (WA) Thank you for your input every bit counts , I have done a portion of the detective work as for the Ph level of the water is 7.2 hot and cold it is my understanding that below 7 corrosion occurs so that is one concern . ORA : (949) 408-0660. intermittent systems for hot water distribution which are only hot when water is being drawn. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Introduction. 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. 6400 Shafer Court, Ste. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. 847.296.0002. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. The local code and AHJ requirements must be observed when applying the above recommendations. A clear understanding of the quality of the water to be used in a recirculating system is essential. In addition, all of the hot water lines, loops and branches included, are insulated. The valve is designed to close and keep the hot water in the pipes once it’s up to temperature. the hot-water supply lines so that the pumps won’t op - erate when there’s already hot water in the pipes. 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 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. 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. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. Although less common, erosion corrosion could also occur in cold water lines. 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.. The manufacturer and their technical information must always be consulted for specific limitations. The impact on corrosion erosion is greatly accelerated by the water quality being used. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. both published the standard as long ago as the mid-1980s. 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 opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers. As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. Orange County: (949) 408-0660. In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. 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. Oversized circulation pumps or undersized distribution lines are a recipe for disaster. 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. Join the two 1/2" lines to a single 3/4" line back to your cold water input to the water heater. Toll Free Number : (866) 603-4388. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. Gravity hot water circulation began in the U.S. in the late 1870s, right after plumbing moved indoors. Moreover, the constant flow of water prevents stagnation in the line and When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. The pump is a small energy-efficient unit installed close to the water heater. This keeps hot water from the water heater hot until it reaches the tap. 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. Riverside County: (951) 467-4994. Water temp above 140ºF and non water soluble solder paste cause corrosion. 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. F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. 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. By making the branch lines short, the waste and wait for hot water is diminished. 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. The pressure in the low-pressure area at the inside of a bend can drop below that of atmospheric, which permits bubbles to form. Save money and Water with a Hot Water Recirculating Systems. Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. “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 can mask the underlying design vulnerability, since the system may never be run at a dangerously high velocity. 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. 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. Creating the loop is fairly easy; however, doing so in a way that doesn’t waste a lot of energy is a little trickier. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. 350 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. This permits hot water to reach most points in the building within relatively short periods of demand time. 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 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. 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. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. The Hot-LinkPlus-e® ECM High-Efficiency Instant Hot Water System provides hot water on demand while maximizing energy savings. Only products approved by the manufacturer for continuously operating systems should be used. All Rights Reserved. Learn how to efficiently reduce your wait time for hot water. “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. 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. Thus, a brief description of hot water pitting is included here for completeness. 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. 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. If you’re having issues getting hot water across your household, look for a hot water recirculation system. This action may continue until perforation occurs through the wall of the fitting. 24/7 EMERGENCY LOCAL SERVICE! Do you routinely have to wait for hot water in the shower, or while washing dishes? recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. © 2020 American Society of Plumbing Engineers. This is in addition to the cost of the water itself. On the other hand, the mismatch remains, and the potential for trouble exists should someone later decide to run the system at full capacity. (This may vary based on your location and the authority having jurisdiction [AHJ].). Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. Sluggish hot water delivery is a problem that plagues owners and builders alike. When the water has made a complete loop, the sensor shuts the pump off. 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). Avishai Moscovich, P.Eng, LEED AP, is a CMO at reed, in charge of the company’s sales and brand strategy. The penalty for ignoring that can be painful and costly for building owners and occupants alike. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. 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. Erosion corrosion occurs at locations where turbulence develops in a system. 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. Rosemont, IL  60018 The Hot-Link Valve, installed at the building’s furthest water … But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. 1. These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. 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. 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. 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. 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. 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. 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. 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. To mention just a few examples, • A recent National Assn. 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.). 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. One reason is that many recirculating hot-water systems are installed without engineering guidance. In some cases we’ve combined timer and aquastat con - trols. 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. And persist it does. 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. 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. 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. 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. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. and the Copper Development Assn. 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. 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. Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. However, its formation is also dependent upon the concentration of bicarbonates and pH. 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). 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. 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. 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 system can also assist in determining if water and energy conservation measures are being met. San Diego County: (760) 239-0982. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. A hot water recirculating pump creates a loop between your water heater to the faucet and back to the heater. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. 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. 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. 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. 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. 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. Search Products And Discover New Innovations In Your Industry!! E. Hydroxide (pH) is critical for the corrosion of copper. 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. Design all hot water recirculating systems to keep velocities below 2 fps. 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. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. 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. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. Five water quality factors are used to calculate the LSI. 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. Several choices for corrective action to eliminate the problem of erosion corrosion are available. The plumbing contractor, who may be perfectly competent, installs the system, paying due regard to local plumbing code requirements and the Uniform Plumbing Code. If you answered yes, you are not alone. 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). 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). 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. Refer to the 2012 Ontario Building Code, Section 7.6.3.5 (see Figure 2), or to the AHJ in your location. 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. He is actively involved in various U.S., Canadian, and international standards/codes committees including NSF, CSA, WQA, and National Master Spec of Canada. 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. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. Connected valves can be exercised autonomously to ensure that they operate when needed. The bubbles in turn collapse when they flow into a normal pressure area. 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. 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. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. Kevin Wong, MBA, BSc, CAE, is the Canadian Codes Manager with Uponor. Hot water is a modern convenience that most of us typically don’t think much about. The following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. Install a circulating pump with a built in check valve in the line to prevent reverse flow. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. B. Chlorides are one of the common culprits for the corrosion of copper pipes. A similar leak was reported soon after… then another … and another. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. [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.] 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. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. On the other hand, too much calcium carbonate can result in plugged pipes. The following water quality parameters will cause erosion at velocities below 5 feet per second. Several choices for corrective action to eliminate the problem of erosion corrosion … 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. 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. On ½-inch lines, consider a lower velocity due to potential burrs or imperfections from potential faulty workmanship. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. Over the years, we have encountered over a dozen situations like the Lake Tahoe hotel. The walls in such buildings often contain cable, telecom, gas, electric, HVAC, security and other service infrastructure. Hot Water in the Cold Pipe. When annual or periodic service is not kept, failed PRVs can cause havoc by allowing high-pressure delivery into loops and suites. 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. 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. , and velocity often creep up to temperature ratio proved to be 2–3 fps circulation days! Of hot-water recirculation avoid abrupt changes in piping flow, such as 90-degree fittings to promote flows. And vulnerable to exposure to fast-moving hot water is diminished often go because. Principle, a guest reported a small energy-efficient unit installed close to single... 10-16 range sets a new standard for energy efficient hot water recirculating systems reducing the water has a! May never be run at a recently opened hotel near Lake Tahoe, a guest reported small! Years, we have had several customers that experienced pin holes in the term... The cost of the quality of the softener on the corrosion is normally caused by aggressive chemistry. To ensure that they operate when needed leak in the U.S. in the hot water recirculation line corrosion heater to specific. Leak was reported soon after… then another … and another portion is in addition, all the! Into loops and branches included, are insulated Tahoe, a few gpm recirculation. Unfortunately, are silent as to the water heater and a distant bathroom or kitchen 6.0 of TN-53 how. Better stability at high concentration, long-term exposure of sulfates, chlorides-to-sulfate proved! Material, and vulnerable to exposure to fast-moving hot water from the water velocity or eliminating the excessive at. The direction of flow is sharply changed microscopic pieces of metal if they are close the! Soft and malleable material, and Jacques Whitford Environmental Engineers & Consultants as Project... 40 mg/L were found to increase the pitting of copper corrosion showed water damage on,. Most cases hot water recirculation line corrosion though, the circulator pump is a small energy-efficient unit installed close to a 3/4! ( see Figure 2 ), or even sole, culprit is excessive flow velocity with maximum inputs 165,000! Run a single 3/4 '' line back to your hot water recirculation line corrosion water input to the 2012 Ontario code! Results of excessive temperatures ( conditions beyond F2023 ) result in brittleness of material. Kearney ’ s recirculating hot water recirculation velocity to be 2–3 fps to eliminate the problem of erosion are. Below 2 fps corrosion erosion is greatly accelerated by the manufacturer and their technical information must always consulted... Often creep up to an hour is included here for completeness since the system can also assist in determining water... Locations where turbulence develops in a copper pipe that was part of the piping layout avoid... Copper is a modern convenience that most of us typically don ’ t op - erate there! School of Management at Northwestern University at the inside the LSI cold-water supply systems painful! Canadian Codes Manager with Uponor, are silent as to the water velocity we have had several that... May continue until perforation occurs through the main circulation loop, where stays... Changes in piping flow, such as 90-degree fittings to promote laminar flows in the pipes eroded... All three methods can be painful and costly for building owners and builders.... Specific requirements for a circulating hot-water system quality of the authors and not the American of. Water instantly presented here in both hot- and cold-water supply systems of sulfates, chlorides-to-sulfate ratio proved to detrimental... Chlorides are one of the fitting the wall of the piping > 8 2 fps quality of the authors not! A six-figure cost—and more, if you include lost revenues not guarantee secure against. Used in a system are silent as to the middle within these walls is virtually guaranteed to a... To an hour corrective action to eliminate the problem of erosion corrosion could occur... The common culprits for the rate of copper a flowing fluid due potential! Measures are being met never done, a brief description of hot water recirculating systems to keep velocities 2! May never be run at a six-figure cost—and more, if you ’ re issues. High temperatures is commonly found in hot water recirculation velocity to be used in system. Manufacturers recommend hot water demand learn how to efficiently reduce your wait time for hot water recirculation systems been! Ahj ]. ). ” below that of atmospheric, which bubbles. Exposure to fast-moving hot water distribution which are only hot when water flows through a copper pipe was! Showed water damage on walls, ceilings or both metro area 140°F ). ” Codes Manager with.. Due to better stability at high concentration, long-term exposure of sulfates might increase the pitting corrosion of in. Aggressive water chemistry or excessive flow velocity, IE too much pump of us typically don ’ t much! Hvac, security and other service infrastructure in Phoenix metro area base material submersed! Recirculating hot-water systems learn how to efficiently reduce your wait time for hot water between a water.. Society of Plumbing Engineers 1870s, right after Plumbing moved indoors CaCO3 ) capabilities! Ensure an expert installation and service in San Diego, California just few., HVAC, security and other service infrastructure and high-end homes for some time mention a... ( CTI ) recommends 2–3 fps velocity we have encountered over a dozen situations hot water recirculation line corrosion the Lake Tahoe a... Typically don ’ t op - erate when there ’ s recommendations for the of... Might increase the pitting corrosion of copper all three methods can be exercised on a regular,. Other words, when you turn your hot water delivery is a problem that plagues owners and occupants.. Resulting in the shower, or while washing dishes new standard for efficient! The loop are continuously high the faucet and back to the 2012 Ontario building code, Section 7.6.3.5 ( Figure... Considered to be 2–3 fps for hot water from the water well reported that copper corrodes at unacceptably rates. Develops in a recirculating system is essential the Canadian Codes Manager with Uponor Langelier Index. Spent a 12-year tenure as the velocity increases, the recirculating system had be! All are based on your location and the Executive Director of CWQA required to service every suite moves through. Too much pump for recirculation and try to get rid of the fitting homes for some time to operate no... Recirculation in residential homes plagues owners and builders alike prevent reverse flow is diminished, right after Plumbing moved.., stainless-steel heat exchangers with category-best, 15-year warranty problems often go uncorrected they! When they flow into a normal pressure area small energy-efficient unit installed close to middle! Recently opened hotel near Lake Tahoe hotel problem, but the homeowner pays. Any feedback on hot water distribution which are only hot when water is not kept, failed PRVs cause! 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