Closed Loop Treatment
A Closed Loop Doesn’t Tell You It’s Failing.
The same water recirculates for years. Nothing evaporates, nothing looks wrong, and the system runs exactly as it always has. That is what makes closed loops easy to neglect and expensive to ignore.
Get Your Loop Tested →The Short Version
Chill Loops and Hot Loops, Treated for Corrosion Instead of Scale.
A closed loop is a sealed circuit. A chill loop moves cold water to your air handlers, a hot loop moves heated water for space heating, and in both cases the water is supposed to stay in the system.
Because nothing evaporates, closed loops do not build scale the way a cooling tower does. Scale is an open-system problem. What a closed loop faces instead is corrosion and biological growth, and both of those work on a timeline that has nothing to do with how hard you run the building.
That is the part most facilities get wrong. A cooling tower announces its problems. A closed loop simply degrades until something downstream stops performing.
How Closed Loops Actually Fail
The inhibitor drops below the protection threshold.
Closed loops need a minimum of 600 ppm sodium nitrite to protect mild steel from corrosion. If you are also expecting freeze protection, you need north of 800 ppm. Below those numbers the loop is not partially protected. It is running unprotected, and nothing about its behavior will tell you so.
Corroding steel coats your heat exchange surfaces in iron.
Once mild steel starts corroding, the iron does not stay put. It plates out across the heat exchange surfaces, and iron is a poor conductor of heat. Less heat moves. Your chillers work harder to hit the same setpoint, run longer, and fail sooner. The energy penalty starts before anything breaks.
Leaks dilute the treatment faster than the calendar does.
Leaks are the primary failure mode in a closed loop, and losing more than roughly 1% of system volume per month is a problem. Every gallon of makeup water arrives with no inhibitor package in it, diluting what is left. Without a meter on the loop this is effectively invisible, and most facilities do not have one.
Makeup water costs you twice.
The treated water you lost is the obvious cost. The second one is quieter: makeup water enters at 85 to 90 degrees and has to be chilled back down to 40. On a loop with a steady leak, that is a permanent load on the chiller that nobody has attributed to a leak nobody has found.
Biological growth builds in the dark.
Closed does not mean sterile. Biological growth develops in a loop and biofilm insulates heat exchange surfaces the same way iron does. A sulfur smell when a loop is opened usually means it has gone untreated for a long time. A non-oxidizing biocide once a year handles it.
The chemistry degrades on its own schedule, not yours.
Sodium nitrite and similar treatments break down on a roughly one-year cycle whether the building ran full or sat empty. A light run schedule does not extend that clock. This is the trap that catches churches and schools hardest, because low utilization feels like low wear.
What the Program Covers
Quarterly Visits, Because That Is What a Closed Loop Needs.
Inhibitor Concentration, Every Visit
Sodium nitrite tested against the threshold for your system and documented in writing. If it has drifted, you find out from a report rather than from a failure.
Corrosion Indicators
pH, along with the copper and mild steel interactions that decide how fast a loop degrades. Azole treatment where copper protection is called for.
Leak Detection and Metering
Volume loss tracked month over month against the 1% threshold. Where there is no meter on the loop, Doug installs one, because a loop you cannot measure is a loop you cannot protect.
Biological Control
Non-oxidizing biocide on an annual cycle, with biofilm and growth assessed at each visit rather than assumed absent because the system is sealed.
Glycol Where It Applies
Loops running glycol need concentration and freeze point verified, and the inhibitor package checked for breakdown. Covered in more depth on the glycol page.
A Written Report, Every Time
Readings, what they mean, and what needs attention, in plain language. Yours to keep and to hand to a board or a finance committee.
A Common Assumption
Your HVAC Contractor Is Probably Not Testing Your Water.
Most facilities assume water treatment is folded into their HVAC service, if they have a contractor at all. In our experience that is rarely true past initial system startup.
HVAC contractors are not equipped to test water. They fix pumps, seals, and fan coils after something fails. Catching the chemistry problem behind the failure is a different trade with different tools.
By the time an inspection reveals what has been happening inside the loop, the damage is already paid for. Retubing a failed chiller starts around $30,000. Full replacement runs $150,000 to $250,000, sometimes more.
Find Out What Your Loop Is Actually Running At.
Doug Moore comes to your facility, tests your closed loops, and gives you a written report in plain language. There is no invoice for the visit. You keep the report either way.
Schedule a Site Assessment →Or call Doug directly: 281-309-2351. He answers on the second ring.
Commercial Water Treatment — Houston Metro and Gulf Coast
1105 Jerry Street, Richmond, TX 77469
281-309-2351
Serving Harris County | Fort Bend County | Montgomery County | Brazoria County
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