--- title: "Closed-Loop System Treatment in Ohio | Hoffman Water" description: "Closed-loop water treatment for heating and chilled-water systems in Ohio: corrosion inhibitors, pH control for mixed metallurgy, glycol management, testing, and ongoing monitoring." canonical: https://www.hoffmanwater.com/closed-loop-treatment.html site: Hoffman Water LLC --- Industrial Water Treatment · Ohio & Surrounding States # Closed-Loop System Treatment. Corrosion protection and pH control for heating and chilled-water loops, including mixed-metallurgy systems. [Schedule Complimentary Plant Survey](https://www.hoffmanwater.com/contact.html) [Call 24/7: (937) 508-8739](tel:+19375088739) **Chemical Engineer-Led** · Since 1998 **Industrial & Commercial** clients across Ohio & surrounding states **AP Tech · Advantage Controls** partners **American-Owned & Operated** · Urbana, Ohio ![Hoffman Water-branded closed-loop control panel with Walchem controller and metering pumps](https://www.hoffmanwater.com/assets/cl-control-panel.jpg) Closed-Loop Treatment ## Closed Loops Corrode From the Inside Closed loops are easy to ignore. They run sealed, the makeup volume is small, and nothing seems to be happening, until corrosion products break loose and clog coils, control valves, and heat exchangers. Every gallon of makeup brings fresh oxygen and hardness into the loop. Without the right inhibitor and pH, that adds up to corrosion from the inside, even when the makeup volume is small. We build closed-loop programs around the metals in your system and check them on a regular schedule. > “If a closed loop needs makeup water often, something is leaking, and that leak feeds oxygen and corrosion straight into the system.” Doug Hoffman, Hoffman Water A Sealed Loop ## Inside a Closed Loop Sealed and recirculating, so the right inhibitor protects mixed metals for years with little makeup. What's Included ## What a Closed-Loop Program Covers One program for hot and chilled systems, matched to the metals in your loop and the way it runs. ### Corrosion Inhibitor Selection The right inhibitor depends on the metals in the loop. We select and dose nitrite, molybdate, or another chemistry to fit your system. ### Deposition & Scale Control Even sealed, a loop can drop scale and deposits from hardness in the makeup. We add deposition and scale control to the program so coils and heat exchangers stay clean. ### pH Adjustment for Mixed Metallurgy Copper, steel, and aluminum each have a different safe pH range. We adjust pH to protect the most sensitive metal in the loop. ### Glycol & Freeze Protection Concentration checks, inhibitor levels, and fluid replacement before degraded glycol turns acidic and starts attacking metal. ### Loop Cleaning & New-System Prep Cleaning, pre-treatment, and start-up of new or fouled loops, so the inhibitor protects clean metal instead of sitting on top of debris. ### Inhibitor & Contaminant Testing Regular testing for inhibitor level, pH, and contaminants, so you catch a problem before it reaches a coil. ### Ongoing Monitoring Scheduled service to keep inhibitor and pH in range as the loop ages and makeup comes and goes. ![Closed-loop skid with three Advantage controllers and six metering pumps installed by Hoffman Water](https://www.hoffmanwater.com/assets/closed-loop-skid.jpg) In the Field ## Clean Installs, Quiet Loops The Hoffman Water team keeps this closed-loop install clean and serviceable. Closed-loop install by Hoffman Water. [Schedule a complimentary plant survey →](https://www.hoffmanwater.com/contact.html) Not sure what's happening inside your loop? We'll test the loop, check inhibitor and pH, and tell you what it needs. [Schedule Complimentary Plant Survey](https://www.hoffmanwater.com/contact.html) [Call 24/7: (937) 508-8739](tel:+19375088739) FAQ ## Closed-Loop Questions Most closed loops need quarterly testing, but it depends on the system. We check loops with frequent makeup, recent repairs, or a history of corrosion more often. The point of testing is to catch a dropping inhibitor level or a pH swing before corrosion products start plugging coils and valves. Mixed metallurgy is the main reason closed loops need a real program instead of a one-time dose. Aluminum narrows the safe pH range, so the inhibitor and pH have to match the most sensitive metal in the loop. We test for it and adjust pH to protect every metal in the system, not the steel alone. Yes. Glycol adds its own requirements: the freeze point has to be verified, and glycol breaks down over time into acids that attack metal. We test glycol concentration and inhibitor levels together and top up or replace the fluid before it turns corrosive. Related reading: [Cooling Towers vs Closed-Loop Systems: Which Needs More Maintenance →](https://www.hoffmanwater.com/blog/cooling-towers-vs-closed-loop-systems-which-needs-more-maintenance) Protect the loop before it clogs. Request a site assessment and we'll build a closed-loop program around your system. [Schedule Complimentary Plant Survey](https://www.hoffmanwater.com/contact.html) [Call 24/7: (937) 508-8739](tel:+19375088739)