Chloride ions were reported to enhance the corrosion rate of copper in the short term and at low concentration. Run a single 1/2" line back from the end of each hot water branch until it gets back to the middle. 350 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. When corrosion occurs, several factors may be implicated, including aggressive water chemistry and improperly soldered joints. 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. 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. Adding softeners that are not properly adjusted will increase salt in the water and increase corrosion. Despite their frustration, most homeowners shrug their shoulders at this problem, but not Gary Klein. Typically, the hot water recirculation arrangement is left to operate with no visibility on system or fixture performance. Several choices for corrective action to eliminate the problem of erosion corrosion … Moreover, the constant flow of water prevents stagnation in the line and The pressure loss of a flowing fluid due to friction varies approximately with the square of the flow velocity. 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 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. 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. For temperatures greater than 140° F (60° C), follow recommendations by the manufacturer. Toll Free Number : (866) 603-4388. RIV : (951) 467-4994. Often, water velocities may be throttled down below pump capacity for reasons that have nothing to do with corrosion. Hot-water circulation loops use a small pump to circulate hot water between a water heater and a distant bathroom or kitchen. In most cases, though, the primary, or even sole, culprit is excessive flow velocity. Erosion Corrosion (for Systems with Brass Fittings). One reason is that many recirculating hot-water systems are installed without engineering guidance. Copper is a soft and malleable material, and vulnerable to exposure to fast-moving hot water. Connected valves can be exercised autonomously to ensure that they operate when needed. 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. 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®. In other words, when you turn your hot water faucets on, you get hot water instantly. 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. 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. 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. 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). 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. 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. Grundfos Hot Water Recirculation With A Return Line - YouTube If you answered yes, you are not alone. On the other hand, the mismatch remains, and the potential for trouble exists should someone later decide to run the system at full capacity. 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. This can mask the underlying design vulnerability, since the system may never be run at a dangerously high velocity. 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. 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. 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. 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). Hot-LinkPlus-e™ by Taco Comfort Solutions® offers high-efficiency, intelligent domestic hot water recirculation ideal for retrofit applications. It’s activated on-demand using a switch or motion-sensing device located near each faucet. 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. 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. In principle, a few straightforward precautions should be enough to prevent copper pipe corrosion in recirculating hot-water systems. Do you routinely have to wait for hot water in the shower, or while washing dishes? The manufacturer and their technical information must always be consulted for specific limitations. 1. You just need a few gpm for recirculation and try to get rid of the softener on the hot water side. Soft Water Plus offers sales, service and professional installation of hot water recirculation system in Phoenix metro area. Erosion corrosion occurs at locations where turbulence develops in a system. 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 … The penalty for ignoring that can be painful and costly for building owners and occupants alike. Would review or supervision by a specifying engineer solve the problem? By making the branch lines short, the waste and wait for hot water is diminished. To further complicate the picture, potential corrosion problems often go uncorrected because they may not manifest themselves for many years. hot water at the desired temperature to arrive at fixtures. 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. “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. Very often, this system does not even show up on the maintenance schedules given to a service provider by the developer or building owner. E. Hydroxide (pH) is critical for the corrosion of copper. 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). 24/7 EMERGENCY LOCAL SERVICE! You get all the water savings of a recirculation loop, with no more energy used than would be needed to feed faraway fixtures without the loop. Connected valves on the domestic hot water system, which are not modulating on a regular basis like in an HVAC system, can be exercised autonomously to ensure that they operate when needed. The pump is a small energy-efficient unit installed close to the water heater. Ultimately, the recirculating system had to be repiped at a six-figure cost—and more, if you include lost revenues. 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. Refer to the 2012 Ontario Building Code, Section 7.6.3.5 (see Figure 2), or to the AHJ in your location. In Kearney’s recirculating hot water systems, temperatures in the loop are continuously high. This is in addition to the cost of the water itself. In such waters, the corrosion likelihood is increased if the ratio S = [ HCO 3 -] / [ SO 4 2 -] < 1.5. Rosemont, IL  60018 The following water quality parameters will cause erosion at velocities below 5 feet per second. recommended “designing all hot water recirculating systems to keep velocities below 5 fps for temperatures up to 60°C (140°F).”. 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. A water-pipe failure within these walls is virtually guaranteed to produce a cascade of costly consequences. Hot water is a modern convenience that most of us typically don’t think much about. 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. 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. A clear understanding of the quality of the water to be used in a recirculating system is essential. Save money and Water with a Hot Water Recirculating Systems. In addition, all of the hot water lines, loops and branches included, are insulated. The system can also … These measures help reduce fuel costs, but the homeowner still pays an energy penalty for the conve-nience of hot-water recirculation. It is good practice to observe the recommendations presented here in both hot- and cold-water supply systems. 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. D. Sulfates are generally considered inert to copper. 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. Five water quality factors are used to calculate the LSI. Follow the manufacturer’s recommendations for the joining or assembly of the piping. All three methods can be implemented and optimized in various ways to minimize wait times and energy consumed. 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 system uses a circulation pump that supplies hot water on demand through a loop of copper plumbing tube situated no more than 10 feet away from any fixture where hot water is used. The phenomenon of cavitation can occur in systems when the flow velocity is high and the direction of flow is sharply changed. The professionals at EZ ensure an expert installation and service in San Diego, California. In some cases we’ve combined timer and aquastat con - trols. 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. It is well reported that copper corrodes at unacceptably high rates at pH &6 and very slowly at pH >8. Creating the loop is fairly easy; however, doing so in a way that doesn’t waste a lot of energy is a little trickier. 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. Cool Blue Harley, Sep 6, 2017 #7 Master Plumber Mark Sensitivity trainer and plumber of mens souls 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. Search Products And Discover New Innovations In Your Industry!! The local code and AHJ requirements must be observed when applying the above recommendations. On-Demand Circulation These days we primarily install on-demand hot-water systems. 847.296.0002. Corrosion. According to AWWA, every valve should be exercised on a regular basis, but it is never done. Hot water recirculation pumps are exposed to flow-accelerated corrosion, potentially a costly problem. The following technical overview has been written in response to inquiries regarding corrosion in hot water recirculating systems and velocity effects. 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. This keeps hot water from the water heater hot until it reaches the tap. By the time our firm was consulted, nearly every room showed water damage on walls, ceilings or both. Thus, even review by an engineer may not guarantee secure protection against flow-accelerated corrosion. both published the standard as long ago as the mid-1980s. Only products approved by the manufacturer for continuously operating systems should be used. In the presence of sulfates, chlorides-to-sulfate ratio proved to be detrimental for the rate of copper corrosion. 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 pressure in the low-pressure area at the inside of a bend can drop below that of atmospheric, which permits bubbles to form. To mention just a few examples, • A recent National Assn. 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. 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). The corrosion is normally caused by aggressive water chemistry or excessive flow velocity resulting in the pipes being eroded on the inside. The pump quickly pushes heated water through the main circulation loop, where it stays hot for up to an hour. 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. 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. 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. 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. Section 6.0 of TN-53 explains how the results of excessive temperatures (conditions beyond F2023) result in brittleness of PEX material. The valve is designed to close and keep the hot water in the pipes once it’s up to temperature. SD : (760) 239-0982. If long-term contact is established between chloride-containing water and copper, chlorides were beneficial in delaying the corrosion of copper. Only during periods of water use do temperatures rise to heated water temperatures. 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 … Thus, a brief description of hot water pitting is included here for completeness. and the Copper Development Assn. Brochantite due to better stability at high temperatures is commonly found in hot water pipes or hot water recirculation systems. But simply controlling flow velocity would eliminate the problem in the great majority of cases. Nearly 100 per cent of residential high-rise buildings utilize domestic hot water recirculation systems to provide hot water to taps on demand. “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. So if the solution appears simple, why does the problem persist? 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. 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