Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. 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. But simply controlling flow velocity would eliminate the problem in the great majority of cases. They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls 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. Grundfos Hot Water Recirculation With A Return Line - YouTube 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 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. 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. Several choices for corrective action to eliminate the problem of erosion corrosion … 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 UP 10-16 range sets a new standard for energy efficient hot water recirculation in residential homes. 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. 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. Usually these systems rely on a dedicated pump, either constantly running or running on a … Corrosion. 847.296.0002. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. 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. 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 the water has made a complete loop, the sensor shuts the pump off. 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. 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. When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. 1. Hot water is a modern convenience that most of us typically don’t think much about. A similar leak was reported soon after… then another … and another. 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. 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. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. This keeps hot water from the water heater hot until it reaches the tap. 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. both published the standard as long ago as the mid-1980s. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. PEX manufacturers recommend hot water recirculation velocity to be 2–3 fps. Several choices for corrective action to eliminate the problem of erosion corrosion are available. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Water temp above 140ºF and non water soluble solder paste cause corrosion. The attack is typically most severe just downstream of a joint or obstruction in the system. 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. 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. Toll Free Number : (866) 603-4388. 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. 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. 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. Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. Follow the manufacturer’s recommendations for the joining or assembly of the piping. 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. 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). Only products approved by the manufacturer for continuously operating systems should be used. By Jose L. Villalobos, P.E., Founder and CEOV&A Consulting Engineers, Oakland, Calif. Understanding the changes to NFPA 70-2020, Designing flexible, safe labs: Electrical, power and lighting, Designing flexible, safe labs: Fire and life safety, Circular economy ideas are leading to better real estate investments, Designing flexible, safe labs: HVAC and plumbing, Top 5 Consulting-Specifying Engineer articles: December 11-17, 2020. The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. Most are caused by using thin wall M over L and high velocity, IE too MUCH pump! Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. 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. Gravity hot water circulation began in the U.S. in the late 1870s, right after plumbing moved indoors. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. One reason is that many recirculating hot-water systems are installed without engineering guidance. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. Join the two 1/2" lines to a single 3/4" line back to your cold water input to the water heater. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. On ½-inch lines, consider a lower velocity due to potential burrs or imperfections from potential faulty workmanship. 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. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. 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 . You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. The professionals at EZ ensure an expert installation and service in San Diego, California. Erosion corrosion occurs at locations where turbulence develops in a system. All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. And persist it does. On the other hand, too much calcium carbonate can result in plugged pipes. 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. 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. 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. This is in addition to the cost of the water itself. The system can also … C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. 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. The Hot-LinkPlus-e® ECM High-Efficiency Instant Hot Water System provides hot water on demand while maximizing energy savings. To mention just a few examples, • A recent National Assn. In addition, all of the hot water lines, loops and branches included, are insulated. 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.). Sluggish hot water delivery is a problem that plagues owners and builders alike. “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. 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 … Avishai is an engineering graduate of Ryerson University and holds an Executive MBA from Kellogg School of Management at Northwestern University. Install a circulating pump with a built in check valve in the line to prevent reverse flow. Rosemont, IL  60018 Introduction. According to AWWA, every valve should be exercised on a regular basis, but it is never done. recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. RIV : (951) 467-4994. At the same time, the circulator pump is constantly running without any feedback on hot water demand. 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. B. Chlorides are one of the common culprits for the corrosion of copper pipes. 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). A clear understanding of the quality of the water to be used in a recirculating system is essential. 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.. Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. The hot water required to service every suite moves constantly through copper pipes. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. Thus, a brief description of hot water pitting is included here for completeness. Over the years, we have encountered over a dozen situations like the Lake Tahoe hotel. 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. So if the solution appears simple, why does the problem persist? Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. The Hot-Link Valve, installed at the building’s furthest water … the hot-water supply lines so that the pumps won’t op - erate when there’s already hot water in the pipes. The penalty for ignoring that can be painful and costly for building owners and occupants alike. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. [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.] Design all hot water recirculating systems to keep velocities below 2 fps. 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 bubbles in turn collapse when they flow into a normal pressure area. 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. Learn how to efficiently reduce your wait time for hot water. 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. Would review or supervision by a specifying engineer solve the problem? These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. 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. All Rights Reserved. He is actively involved in various U.S., Canadian, and international standards/codes committees including NSF, CSA, WQA, and National Master Spec of Canada. The system can also assist in determining if water and energy conservation measures are being met. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. In the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows in the system. ORA : (949) 408-0660. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. 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. 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. 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. 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. 24/7 EMERGENCY LOCAL SERVICE! 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. 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On a regular basis, but not Gary Klein if they are close to the cost the...