Variable Speed

With variable-speed compressors, Conair portable chillers adapt to varying loads, deliver big energy savings

The first available with variable-speed compressors, new 10-ton and 20-ton EP2 Series portable chillers from Conair combine dramatic power savings with the versatility to efficiently handle low, partial, and full chilling loads. In head-to-head tests against 10- and 20-ton chillers equipped with conventional fixed-speed compressors, EP2 Series Portable Chillers deliver energy savings of up to 50% in a range of realistic conditions. This option is available on both water-cooled and air-cooled models.

Chillers with conventional, fixed-speed compressors cannot reduce their cooling capacity by slowing down. To prevent overcooling, they introduce an artificial cooling load using a hot-gas bypass. So, at partial loads, energy savings are minimal. Chillers with newer digital scroll compressors do better, since these compressors can unload some capacity to reduce power consumption for partial loads, but they cannot match the efficiency of variable-speed compressors.

Variable-speed compressors make sense when you need one chiller to efficiently run a variety of loads at less than full chiller capacity. That’s why Conair has introduced optional variable-speed compressors for 10-ton and 20-ton EP2 Series Portable Chillers. Equipped with advanced PLC controls, these chillers constantly monitor load and adjust compressor speed for peak efficiency, essentially changing the size of your chiller as necessary.

Fixed-speed vs. variable-speed: 10 ton chiller

Compared to typical chillers with fixed-speed compressors, Conair’s EP2 Series 10-ton variable-speed chiller provides major power savings at partial loads. At a 30% load, for example, the variable-speed compressor consumes just 36% of full-load power, while the fixed-speed chiller consumes 88% of full-load power – a savings in excess of 50%!


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Fixed-speed vs. variable-speed: 20 ton chiller


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Conair’s 20-ton variable speed chiller generates savings over an even wider range, efficiently handling loads from 3 to 20 tons. This EP2 Series chiller combines a 10-ton variable-speed compressor with a 10-ton fixed-speed compressor to generate impressive savings, especially in the 3- to 8-ton range and the 13- to 16-ton range. Note that energy savings are not as significant in the middle load range, where either compressor -- fixed or variable -- would be running near its full capacity of 10 tons. The curve for the 20-ton fixed-speed chiller is a bit different too. It has two 10-ton compressors so that it can run on just one (half power, more or less) until the second compressor needs to kick in. Still, it is clear that there are significant energy savings to be realized.

What about digital scroll compressors?

Chillers equipped with newer digital scroll compressors show significant power savings over those with fixed-speed compressors because they can partially unload capacity to reduce power consumption for partial loads. But tests show that they cannot match the energy efficiency of variable-speed compressors at the same wide range of partial loads.

Digital-scroll vs. variable speed: 10-ton chiller

Even with a digital scroll compressor (middle line), a 10-ton chiller cannot match the efficiency of Conair’s EP2 Series chiller with a variable-speed compressor (lower line). While both of these options are more far more efficient than fixed-speed chillers, the chiller with the digital compressor uses 58% of full-load power at 30% load and 86% of full-load power at 70% load. The variable-speed compressor in the 10-ton EP2 Series chiller consumes just 36% of full-load power at a 30% load, and just 62% at a 70% load.

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Energy savings = Rapid payback

As shown by the tables below, the remarkable energy savings generated by variable-speed compressors in Conair’s EP2 Series chillers mean rapid payback on your investment, particularly under low and partial load conditions.

10-Ton Air-Cooled Variable-Speed Compressor Option Payback

(Years based on $0.10/kWHr power cost)
Hours/Year
Based on 50 Weeks/Year
Process Load as Percent of Available Chiller Capacity
50% 55% 60% 65% 70% 75% 80% 85% 90%
4,000 hours/year
(16 hours/day, 5 days/week)
1.1 1.1 1.2 1.4 1.5 1.8 2.2 2.9 4.4
6,000 hours/year
(24 hours/day, 5 days/week)
0.7 0.8 0.8 0.9 1.0 1.2 1.5 1.9 2.9
8,400 hours/year
(24 hours/day, 7 days/week)
0.5 0.5 0.6 0.6 0.7 0.8 1.0 1.4 2.1


20-Ton Air-Cooled Variable-Speed Compressor Option Payback

(Years based on $0.10/kWHr power cost)
Hours/Year
Based on 50 Weeks/Year
Process Load as Percent of Available Chiller Capacity
50% 55% 60% 65% 70% 75% 80% 85% 90%
4,000 hours/year
(16 hours/day, 5 days/week)
1.7 1.7 1.7 1.7 1.7 1.9 2.4 3.3 6.0
6,000 hours/year
(24 hours/day, 5 days/week)
1.2 1.2 1.1 1.1 1.1 1.3 1.6 2.2 4.0
8,400 hours/year
(24 hours/day, 7 days/week)
0.8 0.8 0.8 0.8 0.8 0.9 1.1 1.6 2.9


Advanced PLC Controls

The advanced PLC controls of the Conair EP2 Series are the perfect complement for their optional variable-speed compressors. Through a crisp, 7-inch color touch screen display, access to 150 parameters for chiller setup, monitoring, and control make operation a snap. And, behind the scenes, this powerful control system is continually monitoring chiller load and adjusting compressor speed as needed to deliver precise cooling capacity with astonishing energy efficiency.

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