ModulAIR is a water chiller that brings robust serviceability and ASHRAE 90.1-2010 efficiency into a single compact package. Air-cooled chiller sizes are available in 5, 10, 15, 20, 30, and 40 tons. Each chiller can be used as a stand-alone unit or combined for installations up to 550 tons.

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Building on the same premise of serviceability from its water-cooled brother, the new air-cooled modules feature an interconnecting stainless-steel header system. All refrigeration components can be replaced and serviced while the header remains in place. Compressors are isolated in a weather-proof enclosure ensuring compressor and electrical longevity. Optional insulation can be added to this enclosure for sound critical applications.

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The air-cooled ModulAIR has many of the same features of the water-cooled version. For more information on the water-cooled model, click here. Air-cooled models are available with integral free-cooling coils. These coils work by bypassing the cooling water from the evaporator to a secondary coil located in the air-stream. The compressors are shut off and the condenser fans now cool this secondary coil. A built-in diverting valve automatically performs the switch-over. For cold climates, the chiller is available with low ambient controls which include; electronic head-pressure control valves, refrigerant liquid receivers, and heat tracing.

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These chillers are available with R134a refrigerant for standard comfort cooling situations. They are also available with R507A refrigerant which is optimized for food processing, manufacturing and other low temperature applications. ModulAIR is a compact water chiller manufactured by Advance Industrial Refrigeration (AIR). For more information, visit the ModulAIR page.


This apartment building located in Toronto, Canada had a reciprocating water-chiller original to the building – 1968! We conducted an energy audit to determine its performance and confirm the actual capacity of 80 tons.  In addition to saving electricity and securing incentives from the local electric utility, Toronto Hydro, this article will focus on how this unique chiller retrofit saved natural gas and secured incentives from the local gas company- Enbridge!



Most chiller retrofits are intended to improve efficiency and save electricity. How can this chiller installation save natural gas as well? While most chillers reject their condenser heat outdoors through a cooling tower, this chiller diverts waste heat and uses it for domestic hot water instead. That means the chiller can cool the building during summer months and deliver free hot water at the same time! As part of the energy audit, we measured the domestic hot water flow rate and temperatures. This gave an accurate depiction of the actual hot water use in the building. In most high-rise residential buildings, the chiller can develop more than enough heat for the domestic hot water load. In this case, it was determined that 2 ModulAIR chiller modules should be installed: one 25 ton heat recovery module and one 55 ton standard module. This meets the total required cooling capacity of 80 tons while the heat recovery module delivers 240,000 btu/hr of heat at 160 F.



Looking closer at the two modules, you can see the far chiller (25 ton) has an additional heat exchanger (condenser) and circulator pump. The chiller is piped to the boiler loop just like any other boiler. When there is a call for heat, the pump kicks on and moves boiler water through this secondary condenser. The cooling tower water that circulates through the primary condenser is cut off and the chiller begins rejecting heat to the boiler loop.

The new ModulAIR chiller records and sends data so anyone can view it remotely. Below is a graph showing the heat recovery operation for a given day. As you can see, the chiller cycles in and out of heat recovery mode to maintain the domestic hot water temperature at night. During the day, the chiller spends most of its time in full heat recovery mode.

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The chiller at this apartment building runs from June through mid September. During this 14 week time, the heat recovery module had an average demand of 82% and saved over $5,400 in natural gas! Enbridge offered an additional $1,500 incentive. The incremental cost of the heat recovery feature was more than paid for in the first summer of operation.

For more information about this system, visit the ModulAIR page or Contact AIR. We can conduct the audit to determine feasibility, help with the piping layout and confirm energy savings with actual data!


Considering a new chiller plant or chiller retrofit? Many modular water-chillers are focused on the lowest possible capital cost. This means cutting corners on parts that are critical to life span, maintenance, and long term energy efficiency of the chiller plant. In this example, an old modular chiller was replaced with a new ModulAIR chiller. This article focuses on long term energy efficiency using actual data to understand how the old chiller managed to consumed 300% more energy than the chiller that replaced it!

Figure 1: Comparison of energy consumption of old chiller vs. newly installed ModulAIR chiller.

Figure 1: Comparison of energy consumption of old chiller vs. newly installed ModulAIR chiller.










As you can see from Figure 1; the energy consumption of the existing chiller had become extremely poor, more than twice its original published kw / ton value. This graph is based on actual data recorded on site. Both chillers are operating at the same flow rates and temperatures for an equivalent comparison. The Figure also shows that the old chiller operates in distinct power consumption “steps” due to the on / off control nature of its scroll compressors.

Inside of a Brazed Plate condenser, passages are 1/8″ wide.

Inside of a Brazed Plate condenser, passages are 1/8″ wide.

The existing chiller featured brazed plate condensers. Over time, debris from the condenser (cooling tower) system builds up in the small passages of the condenser. Despite multiple attempts to clean the condensers with specialized equipment and chemicals, the efficiency of the chiller continued to deteriorate. There is simply no proper way to clean the inside of a brazed plate condenser! To get this photo of the inside of a brazed plate condenser, we literally had to cut it open. Yes, this chiller had water-strainers too!

Image of a Shell & Tube condenser, passages are 3/4″ wide.

Image of a Shell & Tube condenser, passages are 3/4″ wide.

Shell & tube condensers on the other hand, can be opened and cleaned on a regular basis. This helps maintain heat exchanger performance and prevent situations as shown in Figure 1. To learn more about different types of heat exchangers, see our other blog post.  The end-caps of the condenser can be removed and conventional cleaning equipment can be used to clean the tubes. All ModulAIR chillers feature shell & tube condensers as a standard offering. There is no need to add strainers which can become plugged up causing low flow issues and other maintenance headaches.


As discussed, the new chiller has significant improvements in terms of energy efficiency. This is party due to advancements in compressor technology and party due to having cleanable condensers that will not foul over time. Using measured data, the new chiller saves $22,000 in electricity every summer for this customer and was given incentives from the local government.

New ModulAIR chiller installation shown.

New ModulAIR chiller installation shown.

To learn more about the energy efficiency characteristics of the ModulAIR chiller manufactured by Advance Industrial Refrigeration, click here.


ModulAIR is a water cooled chiller that brings robust serviceability and ASHRAE 90.1-2010 efficiency into a single compact package. Chiller sizes are available in 8, 10, 12, 15, 21, 25, 41, 48 and 55 tons. Each chiller can be used as a stand-alone unit or combined for installations up to 550 tons. Chiller modules of any size can be mix and matched without limitation!

Unparalleled serviceability

Some users try to avoid modular chillers because traditionally they haven’t been as reliable as conventional chillers. ModulAIR brings all the robust features of a full size chiller into a compact foot-print. Fully cleanable shell & tube condensers and replaceable filter driers mean that customers no longer need to sacrifice reliability when a compact design is needed. Standard features such as compressor oil level and flow monitors show that this chiller takes reliability more seriously than the rest.


Unlike other modular chillers, ModulAIR is designed such that the condensers and evaporators can be serviced while the rest of the unit remains in operation. Unions on factory installed water piping can easily be removed to gain access to the front of the condensers for cleaning. The electrical control panels are hinged and rotate outwards allowing for easy access to the compressors. This means that service clearance is required from the front side of the chiller only, resulting in a smaller overall installation.

Smart control features

Smart controls are where this chiller differentiates itself from the rest. Each chiller module can run autonomously. The unique control algorithms are duplicated in each chiller module eliminating the need for any “master” controller. This removes a significant point of failure and improves redundancy for critical applications.

All ModulAIR chillers feature compressors with capacity control from 100% to 10% with advanced unloader technology. Operators no longer need to wonder at which point their chiller is the most efficient. The built in control sequence automatically determines how many compressors should be operational to deliver the lowest energy consumption possible. It doesn’t matter what the conditions might be, ModulAIR will automatically try different operational scenarios to determine which is the most efficient.



For applications where down-time is not acceptable, ModulAIR features a unique high head pressure avoidance sequence. This means the chiller will anticipate a high head pressure lockout situation and make every attempt to remain online during the most harsh conditions. If a cooling tower fan motor fails, or condenser water flow is restricted, the chiller will unload its compressors to take advantage of whatever heat rejection capacity remains available. Conventional chillers will simply continue to control to their chilled water set-point and end up tripping on high head pressure, remaining offline until the facility operator hits the re-set button.

Energy saving options

A wide variety of feature are available on the ModulAIR chiller for users who are concerned with energy efficiency. For systems that require variable primary flow, chillers are available with 2-way motorized valves. This allows the chiller to control to a constant return temperature while saving on chilled water pump energy. The condenser features a water regulating valve to properly control head pressure while reducing the amount of condenser water required in winter months.

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Because of its modular design, other specialized accessory modules can be added to any system. A pre-engineered skid with pumps and tanks is available for a simplified installation. For water cooled systems, a free-cooling module is available which can take advantage of energy savings during winter months. This feature allows the chiller to save on compressor energy by using cold condenser water to cool the chilled water supply, rather than using mechanical cooling all year round.

ModulAIR can also help save energy in applications where cooling and heating is required at the same time. Condenser heat is wasted when it’s rejected outdoors. This can be used to satisfy heating requirements for domestic hot water, space heating, or other process heat loads. Unlike other small chillers that use high pressure refrigerants, ModulAIR uses a medium pressure refrigerant, allowing it to operate at higher discharge pressures more efficiently. This means that users can generate 175 F hot water from this chiller for all their hot water heating requirements!

For more information

ModulAIR is a compact water chiller manufactured by Advance Industrial Refrigeration (AIR). For more information, visit the ModulAIR page.