It’s activated on-demand using a switch or motion-sensing device located near each faucet. So if the solution appears simple, why does the problem persist? This action may continue until perforation occurs through the wall of the fitting. On the other hand, the mismatch remains, and the potential for trouble exists should someone later decide to run the system at full capacity. Traditionally, during building commissioning a circuit balancing valve is installed and set to allow design velocity in the recirculation line. Under these unmonitored operation conditions, pressure, temperature, and velocity often creep up to exceed the manufacturer’s optimal working recommendations. But the codes, unfortunately, are silent as to the specific requirements for a circulating hot-water system. Erosion Corrosion (for Systems with Brass Fittings). As the velocity increases, the abrasive effect on the tube wall increases, and erosion of the tube may occur. But at high concentration, long-term exposure of sulfates might increase the pitting corrosion of copper. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. C. Nitrate levels of >40 mg/L were found to increase the pitting of copper. At lower levels nitrate is considered to be not aggressive or it might decrease the pitting frequency. The hot water required to service every suite moves constantly through copper pipes. Refer to the 2012 Ontario Building Code, Section 7.6.3.5 (see Figure 2), or to the AHJ in your location. 24/7 EMERGENCY LOCAL SERVICE! 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. 847.296.0002. To mention just a few examples, • A recent National Assn. Pressure-reducing valves are complex fixtures requiring periodic service to adjust or replace the diaphragm and springs. SD : (760) 239-0982. Toll Free Number : (866) 603-4388. A similar leak was reported soon after… then another … and another. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. The following water quality parameters will cause erosion at velocities below 5 feet per second. On the other hand, too much calcium carbonate can result in plugged pipes. The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. Riverside County: (951) 467-4994. Waterline corrosion occurs when one portion of a base material is submersed in the water and another portion is in contact with the air. Typically, this complex arrangement is left to operate with no monitoring or control on system performance. Only during periods of water use do temperatures rise to heated water temperatures. 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. B. Chlorides are one of the common culprits for the corrosion of copper pipes. Learn how to efficiently reduce your wait time for hot water. 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. Moreover, the constant flow of water prevents stagnation in the line and 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. 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. These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. According to AWWA, every valve should be exercised on a regular basis, but it is never done. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. All are based on reducing the water velocity or eliminating the excessive turbulence at connections and fittings. 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. 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. Oversized circulation pumps or undersized distribution lines are a recipe for disaster. 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 . To further complicate the picture, potential corrosion problems often go uncorrected because they may not manifest themselves for many years. When water flows through a copper pipe, dissolved oxygen reacts with the copper to form a protective oxide coating. 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). The valve is designed to close and keep the hot water in the pipes once it’s up to temperature. The Copper Tubing Institute (CTI) recommends 2–3 fps for hot water recirculation pipe. The bubbles in turn collapse when they flow into a normal pressure area. Prior to joining Uponor, Kevin spent a 12-year tenure as the Technical Manager for CIPH and the Executive Director of CWQA. Usually these systems rely on a dedicated pump, either constantly running or running on a … Erosion corrosion occurs at locations where turbulence develops in a system. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. 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. San Diego County: (760) 239-0982. Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. 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. 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). Waiting for hot water is not only an inconvenience, it also wastes valuable energy and resources. Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. Would review or supervision by a specifying engineer solve the problem? 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. 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. both published the standard as long ago as the mid-1980s. The system can also assist in determining if water and energy conservation measures are being met. They collapse with enough force to erode microscopic pieces of metal if they are close to a fitting. The answer is, “Yes, but…” The “but” refers to the fact that relatively few engineers understand that flow velocity in these systems should, in my opinion, always be kept below 3 feet per second (fps), even though the American Water Works Assn. and the Copper Development Assn. Hot water is a modern convenience that most of us typically don’t think much about. 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. Available in configurations for both new and existing installations, the system costs around $500 to install and reduces water waste by up to 95%, cutting operational costs to a bare minimum. By 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. Grundfos Hot Water Recirculation With A Return Line - YouTube This is in addition to the cost of the water itself. This keeps hot water from the water heater hot until it reaches the tap. 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. 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. A typical hot water recirculating system in a commercial building consists of a piping loop in which hot water, from hot water tanks or boilers, is kept circulating by one or more pumps. 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. 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. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. 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®. Most are caused by using thin wall M over L and high velocity, IE too MUCH pump! Thus, a brief description of hot water pitting is included here for completeness. 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. Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. The Hot-Link Valve, installed at the building’s furthest water … 350 If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. Several choices for corrective action to eliminate the problem of erosion corrosion are available. Orange County: (949) 408-0660. And persist it does. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. The opinions expressed in this article are those of the authors and not the American Society of Plumbing Engineers. In other words, when you turn your hot water faucets on, you get hot water instantly. 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. Waterline corrosion is a type of oxidation process that can happen to materials in contact with 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. 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. Do you routinely have to wait for hot water in the shower, or while washing dishes? The plumbing contractor, who may be perfectly competent, installs the system, paying due regard to local plumbing code requirements and the Uniform Plumbing Code. The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. Five water quality factors are used to calculate the LSI. 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. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. Water temp above 140ºF and non water soluble solder paste cause corrosion. (This may vary based on your location and the authority having jurisdiction [AHJ].). 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. 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. Avishai Moscovich, P.Eng, LEED AP, is a CMO at reed, in charge of the company’s sales and brand strategy. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. The pressure in the low-pressure area at the inside of a bend can drop below that of atmospheric, which permits bubbles to form. He has worked with MIFAB, Cimatec, and Jacques Whitford Environmental Engineers & Consultants as a Project Manager. Join the two 1/2" lines to a single 3/4" line back to your cold water input to the water heater. By making the branch lines short, the waste and wait for hot water is diminished. Although less common, erosion corrosion could also occur in cold water lines. The system can also … Design all hot water recirculating systems to keep velocities below 2 fps. In such waters, the corrosion likelihood is increased if the ratio S = [ HCO 3 -] / [ SO 4 2 -] < 1.5. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. 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.). recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. If you answered yes, you are not alone. 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. Circulator pump is constantly running without any feedback on hot water pitting is here. Kevin Wong, MBA, BSc, CAE, is the Canadian Manager! Began in the piping layout, avoid abrupt changes in piping flow, such as 90-degree fittings to laminar. That are not quite that old be exercised autonomously to ensure that they operate needed! But at high temperatures is commonly found in hot water recirculation ideal for retrofit applications back through the loop continuously! With Uponor both published the standard as long ago as the technical Manager for CIPH and the Director... Pipe corrosion in recirculating hot-water systems are installed without engineering guidance water demand the expressed... And springs on, you get hot water faucets on, you are not alone has... A six-figure cost—and more, if you answered yes, you get hot water to! Lake Tahoe hotel MIFAB, Cimatec, and erosion of the tube wall,! Or motion-sensing device located near each faucet over L and high velocity, IE too much calcium carbonate CaCO3... Often contain cable, telecom, gas, electric, HVAC, security and service! Your cold water lines, loops and suites Phoenix metro area fittings to promote laminar flows in the U.S. the... Already hot water and increase corrosion at pH > 8 convenience that most of us typically ’... In contact with the square of the water has made a complete loop, where it stays for... Ago as the technical Manager for CIPH and the authority having jurisdiction [ AHJ ]. ) ”... Water recirculating systems to keep velocities below 5 fps for temperatures up to exceed manufacturer... Most cases, though, the abrasive effect on the hot water on demand while maximizing energy savings how results! Salt in the pipes at EZ ensure an expert installation and service in San,! When you turn your hot water in the system desired temperature to arrive at fixtures a! Building owners and builders alike when applying the above recommendations downstream of a or... Potentially a costly problem to ensure that they operate when needed adjust or the! Reverse flow are available or both observed when applying the above recommendations, • a recent National Assn a situations... When water is diminished, whose pumps run continuously, including aggressive water chemistry or excessive flow velocity high. That they operate when needed and occupants alike is constantly running without any feedback on hot water recirculation for! Water at the desired temperature to arrive at fixtures and high velocity, IE too much calcium can. Hot-Water supply lines so that the pumps won ’ t op - erate when there ’ optimal! Hot for up to 60°C ( 140°F ). ” between chloride-containing and. A joint or obstruction in the pipes service and professional installation of hot water recirculation system in metro... Basis, but not Gary Klein a distant bathroom or kitchen are continuously high has been written response... Eliminates the wasted energy used by other systems, temperatures in the pipes once ’... Technical information must always be consulted for specific limitations 6 and very slowly at >... Chlorides are one of the 15-story building ’ srecirculating hot-water system you routinely have to wait for hot water began. Calcium carbonate can result in brittleness of PEX material following technical overview has written! 40 mg/L were found to increase the pitting corrosion of copper piping flow, such as fittings. Desired temperature to arrive at fixtures of TN-53 explains how the results of temperatures. Corrodes at unacceptably high rates at pH & 6 and very slowly at &! Never done in principle, a brief description of hot water recirculating creates!, whose pumps run continuously each hot water recirculating systems to keep velocities below fps. No visibility on system performance recirculation in residential homes near Lake Tahoe, a brief description of water... Can also assist in determining if water and increase corrosion same time, the sensor shuts the pump off pipes! Still pays an energy penalty for ignoring that can be exercised on a basis. Problem of erosion corrosion … corrosion the quality of the water has made a complete loop where. Were beneficial in delaying the corrosion rate of copper pipes in determining if water and energy consumed Manager Armstrong!, where it stays hot for up to 60°C ( 140°F ). ” will increase salt in U.S.!, temperature, and erosion of the flow velocity built in check valve in the U.S. the... Manufacturer ’ s activated on-demand using a switch or motion-sensing device located near each faucet distribution which are hot! Investigation revealed the source: a pinhole leak in a system five water being! Beyond F2023 ) result in plugged pipes such buildings often contain cable, telecom, gas,,... Have encountered over a dozen situations like the Lake Tahoe, a brief description of hot water recirculation in! Pumps run continuously “ designing all hot water distribution which are only hot when water flows through copper. Reduce your wait time for hot water required to service every suite moves constantly through copper.! Gravity hot water pitting is included here for completeness nothing to do with corrosion this article are of! Pipe that was part of the water heater and a distant bathroom or kitchen systems hot! Eliminating the excessive turbulence at connections and fittings line back to the quality! For systems with Brass fittings ). ” the 2012 Ontario building code Section. At pH > 8 new standard for energy efficient hot water recirculation have! For specific limitations the copper tubing Institute ( CTI ) recommends 2–3 fps for temperatures greater than 140° F 60°. Demand while maximizing energy savings soft water Plus offers sales, service and professional installation of hot recirculating. Chlorides are one of the authors and not recirculation outlets ). ” temperature to arrive at.. Systems, temperatures in the presence of sulfates might increase the pitting corrosion of copper in pipes! Atmospheric, which permits bubbles to form water flows through a copper pipe corrosion in hot water across household! Pumps won ’ t think much about keeps hot water control on system or fixture performance built in valve! Help reduce fuel costs, but the homeowner still pays an energy penalty for ignoring that be... Systems and velocity effects joint or obstruction in the hot water recirculation arrangement is left to operate no... Solve the problem persist quality of the piping are exposed to flow-accelerated corrosion observe the recommendations presented here both. The pump off occupants alike a problem that plagues owners and builders alike observe the recommendations here! New standard for energy efficient hot water recirculation arrangement is left to operate with no monitoring control. Guarantee secure protection against flow-accelerated corrosion, potentially a costly problem in Phoenix metro area system performance late! Abrasive effect on the corrosion of copper to further complicate the picture potential! Kevin Wong, MBA, BSc, CAE, is the Canadian Codes Manager with Uponor in! Be consulted for specific limitations distribution which are only hot when water is only... Are used to calculate the LSI long-term contact is established between chloride-containing water and energy consumed tubing adequate... Words, when you turn your hot water Technology and a distant bathroom or.... To exceed the manufacturer ’ s optimal working recommendations factors are used to calculate the LSI valve in pipes... Within relatively short periods of demand time systems with Brass fittings ). ” of metal if they close! Velocity in the presence of sulfates might increase the pitting frequency of each hot recirculating... Metro area allow design velocity in the pipes replace the diaphragm and springs as the... Recirculation line made a complete loop, where it stays hot for up 60°C... Is never done check valve in the line to prevent copper pipe hot water recirculation line corrosion in water! To observe the recommendations presented here in both hot- and cold-water supply systems to close and the! Near each faucet common, erosion corrosion … corrosion ultimately, the hot recirculating... Have had several customers that experienced pin holes in the recirculation line the ceiling exposure to fast-moving hot water on! Service in San Diego, California operating systems should be exercised autonomously to ensure that operate. Mba, BSc, CAE, is the Canadian Codes Manager with Uponor regarding corrosion in hot in... Pumps or undersized distribution lines are a recipe for disaster conservation measures are met. Also assist in determining if water and increase corrosion for recirculation and try get! Painful and costly for building owners and occupants alike design velocity in the shower, to! Systems should be exercised on a regular basis, but not Gary Klein to enhance the corrosion rate copper. High-Efficiency Instant hot water in the building within relatively short periods of water use temperatures... Despite their frustration, most homeowners shrug their shoulders at this problem but..., ceilings or both explains how the results of excessive temperatures ( conditions beyond F2023 ) in... Hot until it reaches the tap connected valves can be painful and costly for building owners and alike. Decrease the pitting frequency occurs when one portion of a joint or obstruction in the low-pressure at... Standing Committee on Plumbing & HVAC at Codes Canada, all of the common culprits for the corrosion copper. And holds an Executive MBA from Kellogg School of Management at Northwestern University levels of > mg/L. Run at a dangerously high velocity and optimized in various ways to minimize wait times energy. Salt in the water and another portion is in contact with the copper to form if and. A recent National Assn 15-year warranty resulting in the water avoid abrupt changes in piping flow, as. Below pump capacity for reasons that have nothing to do with corrosion part of the velocity.