Flow-Splitter for Legionella Control FAQ What does the Flow-Splitter do? The Flow-Splitter is installed on the main hot water riser or ceiling distribution piping and creates a secondary circulating loop serving fixtures within a room. It diverts a controlled portion of flow from the main distribution line into a parallel loop, reducing or eliminating non-circulating branch piping (dead legs). This configuration converts what would otherwise be terminal branch piping into active, circulating piping. Why is reducing dead legs important for Legionella control? Dead legs and low-flow sections are recognized risk factors for Legionella colonization. In stagnant or low-velocity sections of piping: Water age increases Disinfectant residuals dissipate Thermal conditions drift into the Legionella amplification range (25°C–45°C / 77°F–113°F) Biofilm develops along pipe walls Biofilm provides both nutrients and protection for Legionella bacteria. Once established, biofilm can shield organisms from thermal or chemical control measures. By minimizing non-circulating pipe lengths and maintaining hydraulic movement, the Flow-Splitter reduces these conditions. How does the Flow-Splitter operate hydraulically? The device incorporates a dynamic Venturi cartridge installed within the main distribution line. As water flows through the Venturi insert, a pressure differential is created. This differential induces a portion of the flow into the connected loop serving the room fixtures. The induced loop flow occurs: During downstream fixture demand During operation of the system recirculation pump The result is continuous or demand-driven circulation within branch piping that would otherwise remain stagnant. The Venturi principle is a well-established hydraulic mechanism, and the dynamic cartridge allows predictable diversion rates without external power or control systems. How does circulation reduce Legionella risk? Maintaining circulation within branch piping provides several protective engineering effects: Reduced Water Age Continuous movement limits stagnation time and decreases the opportunity for microbial amplification. Improved Thermal Stability Circulation helps maintain target hot water temperatures at fixture connections, limiting temperature drift into growth-supporting ranges. Reduced Temperature Stratification Moving water prevents localized cooling pockets common in static branch lines. Enhanced Disinfectant Distribution In systems utilizing supplemental disinfection (e.g., chlorine, monochloramine, chlorine dioxide, copper-silver ionization), circulation improves distribution and contact consistency. Reduced Biofilm Accumulation While biofilm can still form in any plumbing system, sustained velocity and temperature control reduce favorable colonization conditions. How close are fixtures to the circulating loop? Loop connections are typically made at the fixture stop and are commonly less than 12 inches from the fixture. This significantly shortens non-circulating piping compared to traditional branch layouts, which may allow up to 25 feet of dead leg under certain plumbing codes. From a Legionella risk mitigation perspective, minimizing non-circulating pipe length is considered a best practice beyond minimum code allowances. Does this support Water Management Programs? Yes. The reduction of stagnation and maintenance of controlled thermal conditions aligns with engineering controls recommended in: ASHRAE Guideline 12 ASHRAE Standard 188 Both emphasize control of water age, temperature management, and minimization of dead legs as foundational risk-reduction strategies in building water systems. The Flow-Splitter does not replace a comprehensive Water Management Plan but serves as a mechanical design strategy that supports it. Does the loop qualify as the hot water source under IECC 404.5.1? Yes. The circulating loop created from the Flow-Splitter is considered the hot water source piping to which public lavatory fixtures are connected. This assists designers in complying with IECC energy code provisions while simultaneously enhancing infection control considerations. Why design for less than 25 feet of non-circulating pipe? Although some plumbing codes permit up to 25 feet of branch piping without recirculation, infection control best practices increasingly recommend minimizing stagnant sections wherever feasible — particularly in: Healthcare facilities Long-term care facilities Hospitality environments Multi-occupancy commercial buildings Reducing dead legs improves both user performance (instant hot water) and public health resilience. Summary The Flow-Splitter converts terminal branch piping into actively circulating loop piping using a passive Venturi-based hydraulic mechanism. By reducing dead legs, lowering water age, stabilizing temperature, and improving disinfectant distribution, it functions as an engineering control that supports Legionella risk mitigation within hot water systems. It enhances hydraulic performance, improves user comfort (reduced time-to-tap), and strengthens building water safety infrastructure. Contact Legionella Control Systems at [email protected] or 888-416-8626 for rapid Legionella remediation response service in Indiana, Ohio, Michigan, Illinois, Kentucky, the rest of the Midwest, and throughout the U.S. Our experienced engineers are ready to help you evaluate if a copper-silver ionization system is the best Legionella control solution for your facility. Legionella Control Systems also provides services and equipment for commercial, healthcare, and industrial applications of water softening, deionization, reverse osmosis, and filtering, so contact us today about everything from industrial water equipment service and maintenance programs to leasing or purchasing. Learn more about Legionella Control Systems’ CDC Legionella risk assessment and Legionella testing. Request Proposal Contact Us
