It won’t be long before spring and summer are here, and the need to keep large commercial and residential facilities cool will be top of mind. The chillers we use to achieve comfortable temperatures during warm weather come at a substantial cost, though, as they are often the largest single energy-using component in facilities. This makes comprehensive chiller maintenance critical to making sure they perform efficiently and effectively.

The U.S. Department of Energy estimates that chillers use approximately 20 percent of the total electrical power generated in North America, and they expend up to 30 percent in additional energy due to inefficiencies and poor maintenance. As energy prices increase, finding ways to generate significant energy savings through better chiller efficiency will be integral to keeping costs down.

While chiller efficiencies have improved significantly in recent years, new high-tech chillers often have narrower tolerances, making constant maintenance more crucial than ever for keeping them operating at peak performance. Factor in fouled tubes, leaking refrigerant, changes in water temperature and several other variables, and operating costs can escalate quickly.

Maximizing Chiller Efficiency

While there are several factors that can affect chiller efficiency, cleanliness of heat transfer surfaces is often the largest single factor. Given the fact that a chiller typically can have several miles of tubing making up the condenser and evaporator, proper tube cleaning makes sense as way to keep chiller tubes running as efficiently as possible.

Chiller efficiency declines rapidly when tubes become fouled. Contaminants, such as minerals, scale, mud, algae and other impurities, increase thermal resistance and reduce overall performance. These contaminants accumulate on the water side of transfer surfaces in both closed- and open-loop systems. Fouling occurs gradually over time, depending on the quality and temperature of the water used. The more a chiller becomes fouled, the more energy (and cost) it will consume.

It’s fouling agents like these that make chiller tube cleaning so imperative to energy efficiency. Condenser tubes should be brush-cleaned at least annually to keep them free of contaminants. Tube cleaning kits for heat exchangers, condensers, and other small diameter vessels can help remove heavy deposits from all sizes and shapes of tubes.

Tube Cleaning Methods

The percentages of decreased thermal transfer drop quickly even with what seems like thin layers of contaminants. A coating as thin as .0045 can drop chiller tube efficiency by as much as 44%. The fact that the cleanliness of heat transfer tubes is the single biggest determining factor for chiller efficiency raises the question: What is the best way to keep chiller tubes clean? There are several methods to choose from when trying to optimize chiller efficiency, extend equipment life, and save on energy costs.

• Rod & Brush. The rod and brush method, while low-cost and not requiring much training, can be labor intensive and time-consuming. Brushing tubes manually using a rod of metal tipped with a wire or nylon brush is not only the most primitive way to clean chiller tubes, it might be the most ineffective. The brush bristles tend to swab the tube more than brush it, so the tubes will dry with debris still in them, making the final water flush ineffective.
• Rotary Tube Cleaners. One of the most effective and popular ways to clean chiller tubes, rotary tube cleaners utilize either an electric or air motor to rotate a flexible shaft. They are encased in a plastic casing that transports water to the cleaning tool. Using a variety of brushes and cleaning heads that range from several kinds of buffing tools, scrapers, cutter heads, and nylon, brass, bronze and steel brushes, these cleaning devices are capable of cleaning almost all types of deposits, including hard scale. To achieve the best cleaning results, it is important to choose the right brush and tool for the job.
• Tube Cleaning Guns. Utilizing compressed air and water to propel a cleaning projectile through tubes to remove deposits, tools for this chiller tube cleaning method can range from rubber bullets to brushes to plastic or metal scrapers of various kinds. Tube cleaning guns are also a popular method of cleaning deposits quickly, sometimes in a matter of seconds per tube. They can be used in condensers, chillers, absorbers, water heaters, coolers, and other small diameter pressure vessels. Their light weight makes transfer easy and minimizes user fatigue.
• Chemicals. Using chemicals to clean anything has become much more eco-prohibitive in recent years, and chiller tube cleaning is no exception. This method uses acid solutions to circulate through the tubes in order to break down scale deposits and requires significant training and expertise. While chemicals may (sometimes) be able to clean tubes to bare metal, or at least make brush cleaning that much easier, it is a costly way to clean chiller tubes that can jeopardize the health and safety of those working with it. Given the growing restrictions on hazardous waste disposal, getting rid of used chemicals is difficult, costly and can sometimes come with legal ramifications.
• Online Systems. Online cleaning systems are available for use while the chiller is active, helping to reduce the frequency of downtime. There are two main online tube cleaning types available today: One uses foam balls that circulate through the tubes in the chiller, and the other includes the use of plastic brushes that are installed into each of the tubes. The theory behind the foam balls is that they should work through each and every tube often enough to prevent the tubes from becoming dirty. The plastic brush system features plastic baskets which are permanently attached to both sides of the chiller. Periodically, the direction of the flow of water is reversed to cause the baskets and brushes to travel the length of each tube, removing debris.

Whether you’re removing soft, powdery deposits or cleaning heavily clogged tubes, we have a wide range of versatile, efficient tools—including parts and accessories—to help make your job easier. Our experts are available to answer questions about your specific wet or dry tube cleaning needs. Contact us or use the online chat for advice, including recommended tube cleaning methods and ways to achieve the most energy savings out of your chiller this summer.