{"id":511,"date":"2026-09-23T09:16:30","date_gmt":"2026-09-23T01:16:30","guid":{"rendered":"http:\/\/www.amanecerhealth.com\/blog\/?p=511"},"modified":"2026-09-23T09:16:30","modified_gmt":"2026-09-23T01:16:30","slug":"what-water-treatment-methods-are-suitable-for-water-cooled-screw-chillers-4721-e06f85","status":"publish","type":"post","link":"http:\/\/www.amanecerhealth.com\/blog\/2026\/09\/23\/what-water-treatment-methods-are-suitable-for-water-cooled-screw-chillers-4721-e06f85\/","title":{"rendered":"What water treatment methods are suitable for water – cooled screw chillers?"},"content":{"rendered":"

If you\u2019re reading this, chances are you either own, operate, or manage a facility that runs water-cooled screw chillers\u2014and if so, you know how key proper water treatment is to keeping those bad boys running right. I\u2019ve been in the chiller game for over a decade, supplying water-cooled screw chillers to everything from small manufacturing shops to massive data centers, and let me tell you: I\u2019ve seen firsthand what happens when a team skips basic water treatment. Scale builds up, corrosion sets in, efficiency tanks, and before you know it, you\u2019re looking at a $10,000 repair bill or a whole chiller replacement way sooner than you should be. Today, I\u2019m breaking down the water treatment methods that actually work for these chillers, not the generic fluff you\u2019ll find on random forums. Let\u2019s get into it. Water-cooled Screw Chiller<\/a><\/p>\n

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First, let\u2019s ground this in why water treatment for water-cooled screw chillers isn\u2019t optional. These chillers rely on a closed-loop system (most are, anyway) where water circulates between the condenser and a cooling tower to reject heat. That water\u2019s not pure, though\u2014it has minerals like calcium and magnesium, dissolved oxygen, and even bacteria or algae if you\u2019re not maintaining it. For screw chillers specifically, the screw rotors are precision-machined to within thousandths of an inch. Any gunk on those rotors, or corrosion in the pipes, makes them work harder, use more electricity, and wear out faster. I\u2019ve seen a chiller that was 3 years old run at 60% efficiency because of unaddressed scale\u2014cost the owner like $15k extra in energy bills in that first year alone. So yeah, this stuff matters.<\/p>\n

Let\u2019s start with the most common and most accessible method: chemical water treatment. This is what 80% of the facilities I work with use, and it\u2019s not rocket science, but you\u2019ve got to get the right chemicals for your setup. The main players here are three types of chemicals: corrosion inhibitors, scale inhibitors, and biocides.<\/p>\n

Corrosion inhibitors are non-negotiable. Your chiller\u2019s condenser tubes are usually copper or copper alloy, right? If you don\u2019t add inhibitors, the dissolved oxygen in the water will eat away at those tubes over time. I tell customers to go with either film-forming inhibitors or passivating inhibitors. Film-forming ones create a thin, invisible layer on metal surfaces that stops oxygen and minerals from touching the metal. Passivating ones work by making the metal surface chemically inert\u2014great for closed-loop systems that don\u2019t need much water top-up. For screw chillers, I recommend avoiding generic corrosion inhibitors; some cheap ones can leave residues that mess with the screw rotor clearances. Stick to ones formulated specifically for HVAC closed loops\u2014ask your chemical supplier for ones tested for screw compressor systems, not just regular chillers.<\/p>\n

Next up: scale inhibitors. That\u2019s for the hard water issue. If your makeup water (the water you add to the loop when some evaporates in the cooling tower) has high levels of calcium carbonate, it will precipitate out as scale on the condenser tubes. Scale is like insulation\u2014even 1mm of scale can drop chiller efficiency by 10%. Scale inhibitors work by sequestering those mineral ions, so they don\u2019t bind together and stick to tubes. I\u2019ve had customers try using acid to control scale, but that\u2019s a pain\u2014you have to monitor pH nonstop, and too much acid can eat away at the same metal you\u2019re trying to protect. Chemical scale inhibitors are way more reliable. For facilities with really hard water, I also suggest using a makeup water softener as a pre-step, paired with inhibitors. It cuts down how much chemical you need, so it\u2019s cheaper long-term.<\/p>\n

Then biocides. Bacteria and algae love cooling tower water\u2014warm, moist, lots of nutrients. The worst culprits are biofilms, which are slimy layers that form on surfaces. Biofilms don\u2019t just cause corrosion; they also trap scale and reduce heat transfer, same as actual scale. For water-cooled screw chillers, you can\u2019t use just any biocide. Some oxidizing biocides (like chlorine) can damage the rubber seals in your chiller, which are super important for keeping the refrigerant in the system. I recommend a mix: use a non-oxidizing biocide on a scheduled basis, every 1-2 weeks, plus a weekly shock treatment with a mild oxidizing one if your cooling tower is prone to algae. And don\u2019t overdo it\u2014too much biocide is expensive and can also cause residues that mess with the screw rotors. I once had a customer who used twice the recommended biocide dose, and it left a sticky film on the rotors that made the chiller seize up during peak summer. Oops.<\/p>\n

Now, if chemicals aren\u2019t your vibe (or if you\u2019re in a facility that can\u2019t handle regular chemical dosing), there are physical water treatment methods that work, especially for smaller to mid-sized screw chillers. I\u2019m not talking about the magic magnetic water treatment scams you see online\u2014those don\u2019t work, I\u2019ve tested them. The real physical methods are the ones that use filtration or electrolysis.<\/p>\n

First, side-stream filtration. This is where you take a small portion of the circulating water, filter it, and send it back to the loop. The most common type is multi-media filtration, which uses sand, anthracite, or activated carbon to trap sediment, biofilm particles, and small scale crystals. For water-cooled screw chillers, I usually recommend a 5-micron filter as a minimum. If your facility has issues with biofilm, you can add a bag filter that\u2019s easy to replace, or even a self-cleaning backwash filter so you don\u2019t have to change bags every week. Side-stream filtration works best when paired with chemical treatment, but it can reduce the amount of chemicals you need by up to 30% for most systems. For smaller chillers (under 50 tons), a simple cartridge filter might be all you need instead of a whole multi-media setup.<\/p>\n

Then there\u2019s electrolytic water treatment, also called electronic descaling or electrochemical treatment. This uses a small electrical current passed through the water to change the structure of mineral ions, so they don\u2019t form hard scale on surfaces. Some systems also generate small amounts of oxidizers (like hydrogen peroxide or chlorine) to kill bacteria, so it doubles as a biocide method. I\u2019ve had a few customers with sensitive processes (like food and beverage, where chemicals might contaminate their product) swear by this. No harsh chemicals, no storage, no dosing schedules. But it\u2019s not perfect\u2014it works best for systems with water hardness under 200 ppm, and you have to size the system correctly for your chiller\u2019s flow rate. I\u2019d say it\u2019s a good alternative if you can\u2019t use chemicals, but don\u2019t expect it to fix a chiller that\u2019s already got a ton of built-up scale. You still need to clean the system first, then use electrolysis to maintain it.<\/p>\n

Wait, let\u2019s not skip the most important part no one talks about: regular monitoring and maintenance. You can use all the fancy chemicals or physical methods in the world, but if you don\u2019t check your water quality every month, it\u2019s wasted. For water-cooled screw chillers, you need to test a few key parameters: pH (should be between 8.0 and 9.5 for closed loops), conductivity (to check for mineral buildup), total hardness, and biocide residual. Most of the chillers I supply have optional water quality sensors built in, so you can track this in real time on your phone or computer. That way, if pH drops a little, you can add a tiny amount of buffer before corrosion starts, instead of waiting until you see a problem.<\/p>\n

Also, don\u2019t forget annual condenser tube cleaning. Even if you\u2019re treating the water, some scale or biofilm will build up over time, so you need to get those tubes cleaned. There are two types of cleaning: mechanical (like brushing the inside of the tubes) and chemical cleaning (using a mild, chiller-safe chemical to dissolve built-up scale). I recommend mechanical cleaning every 2 years and chemical cleaning every 4-5 years, depending on your water quality. For screw chillers, don\u2019t use high-pressure water jetting to clean tubes\u2014it can damage the thin walls of the condenser tubes, leading to leaks. I\u2019ve seen that mistake more times than I can count, and it always ends up with a costly repair.<\/p>\n

Let\u2019s talk about what works best for different setups, because one size doesn\u2019t fit all. If you\u2019re a small business with a 100-ton screw chiller for a small office or retail space: go with a basic chemical treatment package, plus a 5-micron side-stream filter, and monthly water testing. It\u2019s low cost, easy to maintain, and will keep your chiller running for 15+ years. If you\u2019re a manufacturing facility with a 500-ton chiller running 24\/7, use a combination: corrosion and scale inhibitors with scheduled biocide doses, plus a multi-media side-stream filter, and weekly water testing. You\u2019ll avoid downtime during production runs, which is way more expensive than the water treatment cost. If you\u2019re a data center or a food processing plant where chemical contamination is a risk: go with electrolytic treatment, side-stream filtration, and regular tube cleaning. No chemicals, meets your safety standards, and keeps the chiller efficient.<\/p>\n

I want to call out a few mistakes I see all the time, just to save you the headache. First: waiting until you have a problem to treat water. A lot of owners only deal with water treatment when their chiller\u2019s efficiency drops or it starts leaking. By then, you\u2019ve already wasted money on extra energy bills and small repairs. Second: using the wrong chemicals. I once had a customer use a cheap generic corrosion inhibitor that left a gummy residue on the screw rotors\u2014they had to take the chiller apart, clean the rotors, and replace a seal, which cost $8k. Third: sizing physical treatment systems wrong. A lot of people buy a magnetic filter off Amazon that\u2019s way too small for their chiller\u2019s flow rate, so it does nothing. Do your research, or ask your chiller supplier (that\u2019s me!) to help you size it.<\/p>\n

At the end of the day, water treatment for water-cooled screw chillers is all about balance. You don\u2019t need to overcomplicate it, but you can\u2019t skip it either. It\u2019s the easiest way to extend your chiller\u2019s lifespan by 5-10 years, cut energy use by 15-25%, and avoid costly downtime. If you\u2019re not sure what method is right for your chiller, or if you want to upgrade your current water treatment setup, reach out to us to talk through your needs. We\u2019ve worked with hundreds of facilities to customize water treatment plans that fit their budget and their equipment, no one-size-fits-all junk.<\/p>\n

Before I wrap up, a quick note: I always tell customers that the best water treatment plan starts with using properly treated makeup water in the first place. If you\u2019re using raw tap water straight from the ground, you\u2019re adding extra minerals that make your treatment job harder. A little pre-treatment for makeup water (like a softener or reverse osmosis) goes a long way.<\/p>\n

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Don\u2019t wait until your chiller is in trouble. Even if your chiller is running fine, a quick water test and a review of your treatment plan can save you thousands down the line. We\u2019re here to help you figure out what works for you, no sales pitch\u2014just honest advice from someone who\u2019s been in this game long enough to know what actually works. If you\u2019re ready to chat about your water-cooled screw chiller and the right water treatment for your needs, reach out to our team to connect for a no-obligation consultation. We can help you assess your current setup, recommend the right chemicals or systems, and make sure your chiller stays running efficiently for years to come.<\/p>\n

HVAC Terminal Unit<\/a> References:<\/p>\n

    \n
  1. ASHRAE. HVAC Applications Handbook, 2023.<\/li>\n
  2. Carrier Corporation. Water Treatment Guidelines for Water-Cooled Chillers, 2022.<\/li>\n
  3. Hydraulic Institute. Water Treatment for Closed-Loop HVAC Systems, 2021.<\/li>\n
  4. EPA. Best Management Practices for Cooling Water Systems, 2020.<\/li>\n<\/ol>\n
    \n

    Hangzhou Dayu HVAC Engineering Co., Ltd.<\/a>
    As one of the most professional water-cooled screw chiller manufacturers and suppliers in China, we have world-leading production equipment and strong manufacturing capabilities. If you’re going to buy customized water-cooled screw chiller made in China, welcome to get quotation from our factory. For price consultation, contact us.
    Address: Room 1004, Building 1, Xicheng Business Tower, Xihu District, Hangzhou City, Zhejiang Province, China
    E-mail: info@hi-hvac.com
    WebSite:     https:\/\/www.hi-hvac.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

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