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Redefining Modularity: Modern vs. Traditional Modular Chillers

Posted by Tom McDermott on 07/26/2017

 

Modular chillers have come a long way in the last six to eight years. What once was a viable solution only for retrofits, cooling and tight spaces, has become one of the industry’s most flexible and versatile HVAC systems. As traditional modular chillers give way to modern technologies, the industry is learning to expect the unexpected and rethink what’s possible. We no longer have to compromise for one benefit over another. Let’s take a look at some of the surprising, but key characteristics redefining modularity.

Changing the definition of redundancy: True redundancy means no downtime (even during maintenance)
Whether a mission critical, commercial building or a hospitality application any downtime is costly and stressful. Regardless of application, you need confidence that your system will perform all day, every day. It is inevitable, however, that at some point your chiller will require maintenance or you’ll experience an unexpected point of failure. With backup generators that aren’t always sized properly this elevates the need to look for a system that offers true redundancy. Traditional modular chillers, that retain their design from the 1990s, have a single power source, so if one unit needs to be serviced the whole bank would go offline. New modular chillers are designed with separate electrical feeds providing a built-in redundancy. If one module fails or needs to be shut down for maintenance, the other modules can continue to operate to keep your building running at full capacity.

Extreme design flexibility with the ability to heat, cool or simultaneously heat & cool
Chillers, as the name implies, have long been seen as a staple for their cooling capabilities. Unlike first generation modular chillers, today’s have the ability to provide heating, cooling, heat recovery and heat pump technology in each module. Some even harness both air and water to achieve simultaneous heating and cooling, without geothermal. This means, there’s no need to throw away the heat these chillers generate as today’s modular chiller technologies enable you to recover and harness it. Not only does this provide tremendous flexibility and multi-functional configurations, but it also offers energy efficiencies and cost savings unattainable by any other system. This ability, through individual modules, enables the system to recover heat from one of the cooling modules, allowing users to harness the heat already produced in another part of the building. This could mean cooling one room in your building while supplying recovered heat in another, customizing low temperature chilled water requirements for an operating room suite without compromising efficiency in the rest of the hospital for comfort cooling, or simply redistributing heat to make domestic hot water.

Harness only the energy you need and not a kilowatt-hour more: Increased efficiency, lower total cost of ownership
Sticker price is important but it doesn’t tell the full story. When selecting a modular chiller, consider the expected total cost of ownership throughout the lifespan of the equipment. This can save you money in the long-run. When it comes to controlling costs and boosting energy efficiency, modern modular chillers have the ability to outperform the rest because they use only the energy needed, and nothing more. While they function as one piece of equipment, the modules are enabled individually based upon leaving chilled water and hot water control temperature setpoints. This improves turndown capacity when a building is partially occupied, during off-peak hours or during the spring-summer start up period and fall-winter changeover days. They are powerful enough to cool or heat an entire building on peak days, but can also be turned down to power only one or two units, significantly reducing the total cost of ownership. And, when you consider modular chillers can eliminate the costs and maintenance of boilers or cooling towers, the cost savings really start to add up.

Easy expandability & component configuration speeds up installation and access time
Whether a renovation or a new construction, modern modular chillers make expanding your capacity easy with friendlier component configuration and streamlined water piping. First generation designs make modular chillers top heavy, but modern ones have moved the compressors from the top of the unit to the front and placed them lower for a low center of gravity to ease handling during installation. Additionally, modern modular chillers, especially those that have the ability to recover heat for simultaneous heating and cooling, are designed so that all water piping connections can be made on one end. Expansion onto the chiller bank occurs at the other end without the need to disconnect and weld new pipes together as is the case with traditional modular chillers. New modular chillers also make expandability easier, as they can complement conventional systems, allowing building owners to expand capacity and obtain all the cooling and heating benefits of truly tailored turndown and redundancy associated with them, while leveraging their existing cooling and heating systems.

Maintenance made even easier
Not only do modern modular chiller technologies offer the ability to service modules individually, eliminating downtime, but their design makes them inherently easier to maintain. With the compressors placed in front and lower, it is easier to access when servicing is required. Additionally, headers no longer block the heat exchangers as they’ve been relocated from the front and back of the unit to the top. Once connected, they don’t have to be taken apart for easy serviceability. Off the shelf components and simplicity of design, eliminates the need for factory technicians for servicing. However, equipment startup should always be performed by factory certified technicians. Modular chillers utilize brazed plate heat exchangers which need to be back flushed in order to clean them. Modern units are designed with individual flush ports for each heat exchanger, which make it easy to clean the individual module heat exchanger while the rest of the modular bank continues to operate. This not only maintains energy efficiency of the building but it eliminates the need to shut down the full bank of chillers, reduces the risk of damaging the heat exchanger and reduces costs from needing to hire outside service support that is frequently required with traditional modular chillers.

The refrigerant advantage: Ease of ASHRAE Standard 15 compliance
Inherent to all modular chillers – traditional and modern – but frequently overlooked, is the ease of compliance with ASHRAE Standard 15 mechanical ventilation standards. While refrigerant leaks are potentially dangerous, modern modular chiller systems are compliant with today’s standards because of their small charge in comparison to volume of the mechanical room. Considering that each module contains two refrigerant circuits, the largest circuit from a 250-ton modular chiller can contain only 25 tons of refrigerant, which is typically well within the acceptable range of concentration in the mechanical room space. This advantage eliminates the need for costly design and installation of ventilation, monitoring and safety equipment required with conventional chillers, further lowering the total cost of ownership.

 

About the Author: Tom McDermott is the director of sales at ClimaCool with 25 years of industry experience.