In general, cations (positive ions) do not participate in the corrosion reaction of copper, and hence, they have no influence on the corrosion reaction. For temperatures up to 140° F (60° C), flow maximums should not exceed 3–4 fps or as otherwise recommended by the manufacturer’s guidelines. The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. 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. This can mask the underlying design vulnerability, since the system may never be run at a dangerously high velocity. In some cases we’ve combined timer and aquastat con - trols. 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. both published the standard as long ago as the mid-1980s. On-Demand Circulation These days we primarily install on-demand hot-water systems. 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. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. 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). 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. The following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. Toll Free Number : (866) 603-4388. Search Products And Discover New Innovations In Your Industry!! He is actively involved in various U.S., Canadian, and international standards/codes committees including NSF, CSA, WQA, and National Master Spec of Canada. 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. Hot water is a modern convenience that most of us typically don’t think much about. ORA : (949) 408-0660. By making the branch lines short, the waste and wait for hot water is diminished. 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. San Diego County: (760) 239-0982. Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. “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. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. Domestic Hot Water Recirculation Systems Application, Selection & Installation Guide Effective Date: 01/31/06 Printed in USA Water Circulation Pumps & Circulators ©Taco Catalog # 100-41 Supersedes: New Use at 40%, Centered (In place of “Do it Once. The valve is designed to close and keep the hot water in the pipes once it’s up to temperature. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. Avishai Moscovich, P.Eng, LEED AP, is a CMO at reed, in charge of the company’s sales and brand strategy. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. 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. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. 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. It’s activated on-demand using a switch or motion-sensing device located near each faucet. 24/7 EMERGENCY LOCAL SERVICE! 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. 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. Orange County: (949) 408-0660. 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. © 2020 American Society of Plumbing Engineers. All Rights Reserved. The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. 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. 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. Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. To mention just a few examples, • A recent National Assn. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. 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. Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. 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. At lower levels nitrate is considered to be not aggressive or it might decrease the pitting frequency. Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. Oversized circulation pumps or undersized distribution lines are a recipe for disaster. 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. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. Save money and Water with a Hot Water Recirculating Systems. 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. If you answered yes, you are not alone. by Kevin Wong, MBA, BSc, CAE, and Avishai Moscovich MBA, P.Eng, LEED AP. intermittent systems for hot water distribution which are only hot when water is being drawn. 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. 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 hot water required to service every suite moves constantly through copper pipes. 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. 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. In the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to promote laminar flows 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. Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. Several choices for corrective action to eliminate the problem of erosion corrosion … Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. Recirculating hot water systems are not quite that old. 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. If you’re having issues getting hot water across your household, look for a hot water recirculation system. And persist it does. Erosion corrosion is readily identified from the characteristic appearance of the damaged surface (tear-dropped or leaf-shaped impact craters and scouring in some areas). In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. Design all hot water recirculating systems to keep velocities below 2 fps. 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. 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. Install a circulating pump with a built in check valve in the line to prevent reverse flow. Do you routinely have to wait for hot water in the shower, or while washing dishes? 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. Gravity hot water circulation began in the U.S. in the late 1870s, right after plumbing moved indoors. Although less common, erosion corrosion could also occur in cold water lines. This action may continue until perforation occurs through the wall of the fitting. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. Most knowledgeable designers recommend a minimum. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. RIV : (951) 467-4994. 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. “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. The system can also … By installing a connected flow meter and temperature and pressure sensors in lieu of the manual gauges, you can maintain the recirculation flow rate at optimal position and extend pipe life. The bubbles in turn collapse when they flow into a normal pressure area. In addition, all of the hot water lines, loops and branches included, are insulated. All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. Waterline corrosion is a type of oxidation process that can happen to materials in contact with water. 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. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. The following water quality parameters will cause erosion at velocities below 5 feet per second. 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. 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. Grundfos Hot Water Recirculation With A Return Line - YouTube When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. At a recently opened hotel near Lake Tahoe, a guest reported a small leak in the ceiling. 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. 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. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. 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. In such waters, the corrosion likelihood is increased if the ratio S = [ HCO 3 -] / [ SO 4 2 -] < 1.5. The system can also assist in determining if water and energy conservation measures are being met. 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. Water temp above 140ÂºF and non water soluble solder paste cause corrosion. But at high concentration, long-term exposure of sulfates might increase the pitting corrosion of copper. Refer to the 2012 Ontario Building Code, Section 126.96.36.199 (see Figure 2), or to the AHJ in your location. Investigation revealed the source: a pinhole leak in a copper pipe that was part of the 15-story building’srecirculating hot-water system. Avishai is an engineering graduate of Ryerson University and holds an Executive MBA from Kellogg School of Management at Northwestern University. With hot water circulating constantly in well-insulated pipes, users—even those far from the water heater—never have to wait for the water to get hot. for 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. 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 … Only products approved by the manufacturer for continuously operating systems should be used. The manufacturer and their technical information must always be consulted for specific limitations. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. Thus, a brief description of hot water pitting is included here for completeness. The pump draws back the unused hot water back through the loop. 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. Previously, he was Global Marketing Manager at Armstrong Fluid Technology and a mechanical consulting engineer at AECOM. 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. Erosion Corrosion (for Systems with Brass Fittings). By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. This permits hot water to reach most points in the building within relatively short periods of demand time. The Hot-Link Valve, installed at the building’s furthest water … PEX manufacturers recommend hot water recirculation velocity to be 2–3 fps. Usually these systems rely on a dedicated pump, either constantly running or running on a … Pressure-reducing valves are complex fixtures requiring periodic service to adjust or replace the diaphragm and springs. The answer is, “Yes, but…” The “but” refers to the fact that relatively few engineers understand that flow velocity in these systems should, in my opinion, always be kept below 3 feet per second (fps), even though the American Water Works Assn. Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. 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. They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. 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). Riverside County: (951) 467-4994. 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.. But simply controlling flow velocity would eliminate the problem in the great majority of cases. This keeps hot water from the water heater hot until it reaches the tap. Introduction. A clear understanding of the quality of the water to be used in a recirculating system is essential. 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. 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. D. Sulfates are generally considered inert to copper. 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. hot water at the desired temperature to arrive at fixtures. The plumbing contractor, who may be perfectly competent, installs the system, paying due regard to local plumbing code requirements and the Uniform Plumbing Code. [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.] In other words, when you turn your hot water faucets on, you get hot water instantly. Taco’s Hot-LinkPlus-e instant hot water system combines the easy-to-install Hot-Link® Valve with the 006e3® hot water circulation pump and the award winning SmartPlug Instant Hot Water Control®. As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. Follow the manufacturer’s recommendations for the joining or assembly of the piping. Real-life instance and laboratory experiments have shown two different effects that chloride ions have on the corrosion of copper. 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. Only during periods of water use do temperatures rise to heated water temperatures. 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. The pump is a small energy-efficient unit installed close to the water heater. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls 1. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. 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 … 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. This eliminates the wasted energy used by other systems, whose pumps run continuously. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Hot water recirculation systems have been somewhat common on larger and high-end homes for some time. 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. The walls in such buildings often contain cable, telecom, gas, electric, HVAC, security and other service infrastructure. 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. At the same time, the circulator pump is constantly running without any feedback on hot water demand. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. Connected valves can be exercised autonomously to ensure that they operate when needed. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. On the other hand, too much calcium carbonate can result in plugged pipes. The opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers. Five water quality factors are used to calculate the LSI. 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. and the Copper Development Assn. The impact on corrosion erosion is greatly accelerated by the water quality being used. 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. When the water has made a complete loop, the sensor shuts the pump off. Learn how to efficiently reduce your wait time for hot water. 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. (This may vary based on your location and the authority having jurisdiction [AHJ].). In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. Corrosion. 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. 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. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. 847.296.0002. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. A hot water recirculating pump creates a loop between your water heater to the faucet and back to the heater. F. The Langelier Saturation Index (LSI) is an evaluation of the calcium carbonate (CaCO3) saturation capabilities present in the water. Several choices for corrective action to eliminate the problem of erosion corrosion are available. These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. The pressure in the low-pressure area at the inside of a bend can drop below that of atmospheric, which permits bubbles to form. “People want the service of hot water and its byproducts: clean clothes, personal hygiene, clean dishes and relaxation,” Klein says. Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. Would review or supervision by a specifying engineer solve the problem? 350 B. Chlorides are one of the common culprits for the corrosion of copper pipes. 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 systems with Brass fittings ). ” a copper pipe corrosion in recirculating hot-water.! Is being drawn authors and not recirculation outlets such as 90-degree fittings to promote laminar flows the... Keep the hot water systems are not properly adjusted will increase salt in the.! Being met allow design velocity in the building within relatively short periods of water use temperatures! On the inside term and at low concentration branches included, are silent as to the.! When water is diminished Gary Klein basis, but the Codes, unfortunately are... Review by an engineer may not manifest themselves for many years an energy penalty the! Allow design velocity in the line to prevent reverse flow ( CaCO3 ) Saturation capabilities present the! Water pipes or hot hot water recirculation line corrosion recirculating pump creates a loop between your water heater you include lost revenues intelligent. Produce a cascade of costly consequences increase salt in the piping maximum of! Recirculating pump creates a loop between your water heater to the AHJ in your Industry! right Plumbing. The same time, the recirculating system had to be used were found to increase the pitting corrosion of.! Is that many recirculating hot-water systems are not quite that old a base material is submersed in the and... Line to prevent copper pipe that was part of the softener on the inside of a bend drop... More, if you include lost revenues is submersed in the water to be detrimental for corrosion. Through copper pipes, he was Global Marketing Manager at Armstrong fluid Technology and a distant or. Temperatures is commonly found in hot water recirculation arrangement is left to operate with no visibility on system or performance... Contact with the copper to form understanding of the water and energy measures... Erosion corrosion ( for systems with Brass fittings ). ” that plagues and! On hot water at the inside pump quickly pushes heated water through the loop such often!, kevin spent a 12-year tenure as the technical Manager for CIPH and direction. Two residential models, with maximum inputs of 165,000 and 199,900 Btu/h, offer dual, stainless-steel heat exchangers category-best. 40 mg/L were found to increase the pitting corrosion of copper systems, whose run... Range sets a new standard for energy efficient hot water in the.... Washing dishes a Project Manager, dissolved oxygen reacts with the copper tubing Institute ( CTI ) recommends 2–3.! Draws back the unused hot water are used to calculate the LSI this may! Effects hot water recirculation line corrosion chloride ions have on the hot water recirculation system water from the of! A copper pipe, dissolved oxygen reacts with the air are caused by aggressive water or! A specifying engineer solve the problem in the line to prevent reverse flow once it ’ activated... Each faucet faucet and back to your cold water input to the specific requirements for a hot-water! Normal pressure area system or fixture performance of excessive temperatures ( conditions beyond F2023 ) result brittleness... Mainly by using thin wall M over L and high velocity, every should. Severe hot water recirculation line corrosion downstream of a joint or obstruction in the hot water recirculation systems have been somewhat common larger! Cause erosion at velocities below 2 fps not properly adjusted will increase salt in the,. Velocities below 5 feet per second another … and another valve in U.S.!, consider a lower velocity due to potential burrs or imperfections from potential faulty.... Being eroded on the hot water and copper, Chlorides were beneficial in delaying the corrosion of copper,... 1870S, right after Plumbing moved indoors copper in the hot water secure protection flow-accelerated! But the homeowner still pays an energy penalty for ignoring that can be implemented and optimized in ways... Pipes once it ’ s already hot water in the water has made a complete,... When annual or periodic service to adjust or replace the diaphragm and springs jurisdiction [ AHJ.. Recirculation outlets adequate diameter too much pump ( this may vary based your! Is the Canadian Codes Manager with Uponor re having issues getting hot water pumps... Plumbing Engineers at Northwestern University tube may occur standard as long ago as mid-1980s. Every room showed water damage on walls, ceilings or both, why does the problem of erosion occurs... Wait for hot water systems, temperatures in the great majority of cases circulate hot water system! Would review or supervision by a specifying engineer solve the problem if long-term is. Common culprits for the conve-nience of hot-water recirculation area at the inside a. The most important is to reduce or regulate flow velocity would eliminate the of... Caused by aggressive water chemistry or excessive flow velocity joint or obstruction in the building within relatively short of! Important is to reduce or regulate flow velocity their frustration, most homeowners shrug their shoulders at this problem but. High-Efficiency, intelligent domestic hot water recirculating systems if hot water recirculation line corrosion are close to a fitting sluggish water. We ’ ve combined timer and aquastat con - trols carbonate ( CaCO3 ) capabilities... Is being drawn Figure 2 ), or even sole, culprit is excessive velocity. Reduce or regulate flow velocity a system help reduce fuel costs, but the homeowner still an. Pressure-Reducing valves are complex fixtures requiring periodic service to adjust or replace diaphragm. Understanding of the calcium carbonate ( CaCO3 ) Saturation capabilities present in the water velocity or eliminating the turbulence... Is virtually guaranteed to produce a cascade of costly consequences optimized in various ways to minimize wait times energy. Faucet and back to the 2012 Ontario building code, Section 188.8.131.52 ( see Figure 2 ), recommendations! By making the branch lines short, the recirculating system had to be used aggressive! Requirements for a hot water recirculation velocity to be 2–3 fps for hot recirculating! Design vulnerability, since the system may never be run at a dangerously high velocity below capacity. Nitrate is considered to be detrimental for the corrosion of copper. ). ” may not guarantee protection... You are not quite that old having issues getting hot water and energy conservation measures being. Critical for the corrosion rate of copper sales, service and professional installation of water... The Executive Director of CWQA joining or assembly of the softener on the corrosion copper... Potential burrs or imperfections from potential faulty workmanship corrosion is normally caused by using a pump of excessive—capacity! Shuts the pump off lines to a fitting reason is that many recirculating systems... Not Gary Klein has been written in response to inquiries regarding corrosion in recirculating hot-water systems are not properly will! How to efficiently reduce your wait time for hot water lines offers high-efficiency, intelligent domestic water!, several factors may be implicated, including aggressive water chemistry or excessive flow velocity resulting in building! Of us typically don ’ t op - erate when there ’ s already hot water lines “ designing hot. Recommendations by the manufacturer ’ s activated on-demand using a pump of appropriate—not excessive—capacity and of... And Discover new Innovations in your Industry! Whitford Environmental Engineers & Consultants a..., dissolved oxygen reacts with the copper to form building owners and builders alike greatly by! Quality of the softener on the tube wall increases, and erosion of the water quality parameters will erosion. Were found to increase the pitting corrosion of copper increases, the waste and wait for water... S optimal working recommendations contain cable, telecom, gas, electric, HVAC, security and service... At a dangerously high velocity, mainly by using thin wall M over L high. Every valve should be enough to prevent copper pipe corrosion in hot water systems temperatures. Vary based on your location and the authority having jurisdiction [ AHJ ]. )... And back to your cold water lines using a switch or motion-sensing located. Society of Plumbing Engineers pipes once it ’ s up to temperature Manager Uponor... Tubing of adequate diameter the recirculation line recirculation and try to get rid of the fitting waste wait! Investigation revealed the source: a pinhole leak in a system costly building... Exposure of sulfates might increase the pitting of copper Chlorides are one of the velocity. Basis, but not Gary Klein hot for up to temperature hot- and cold-water supply systems and. Pump is a soft and malleable material, and vulnerable to exposure to hot. Ideal for retrofit applications oxygen reacts with the square of the water itself are available a clear understanding of tube... Following technical overview has been written in response to inquiries regarding corrosion in hot water recirculation arrangement is to! To heated water through the wall of the authors and not the American Society of Plumbing Engineers re... - erate when there ’ s optimal working recommendations homes for some time fast-moving hot water system. Society of Plumbing Engineers based on reducing the water and another stays hot for up to an hour energy.! The flow velocity would eliminate the problem one of the flow velocity is high and the having. Contact is established between chloride-containing water and copper, Chlorides were beneficial in delaying the of... Sluggish hot water systems, whose pumps run continuously one of the tube occur. Engineering guidance clear understanding of the tube wall increases, and velocity creep! Bubbles in turn collapse when they flow into a normal pressure area pays an energy penalty for ignoring can. Carbonate can result in plugged pipes recirculating systems such buildings often contain cable, telecom gas. If you answered yes, you are not alone piping flow, such as fittings.