Motivair Free Cooling chillers are designed for completely automatic operation in a single, self-contained chiller package.  They are ideally applied to any year-round cooling application in central & northern states and Canada.   Data Centers, Hospitals, industrial process cooling and comfort HVAC can all benefit from a Motivair Free Cooling Chiller. Higher chilled water temperature equals greater free cooling savings in any location.  Motivair offers a free analysis of Free Cooling savings in any location, and usually the payback on the initial investment is recovered within the first year of operation.

Motivair Free Cooling Chillers are packaged air-cooled chillers with integrated free cooling components, including free cooling coils, 3-way motorized valve, VFD fan operation and custom PLC controller.  No operator intervention is required to initiate the change from mechanical cooling to Free Cooling, and back again.  The change is seamless, so there are no chilled water temperature fluctuations at any stage of the operation.

MLC-FC Free Cooling chillers cover a capacity range from 70 through 300 tons at standard ARI rating conditions.  They feature two independent screw compressor circuits with automatic unloading or stepless capacity control. In warmer climates, the chillers functions as standard air-cooled chillers. Compressors are sequenced & controlled by the PLC, based on return chilled glycol temperature, sensed at the inlet to the evaporator.  When the outside ambient temperature falls below the return glycol temperature, the sensor at the inlet to the chiller signals the PLC to power the actuator of the Free Cooling valve (VFC) and the return glycol is diverted through the Free Cooling coils, which are located in front of the condenser coils.  This allows the condenser fans to draw ambient air over the free cooling coils before the condenser coils, saving considerable fan power over separate dry coolers.

As the outside ambient temperature falls further, the PLC controller sequentially unloads the two screw compressors, based on a signal from the sensor at the inlet to the evaporator.  This allows proportional control of the chiller glycol temperature without any temperature steps or spikes.  At 10°F below the leaving glycol temperature set point Motivair Free Cooling Chillers achieve 50% Free Cooling.  Whenever a compressor is operating at any load percentage the fans for that compressor circuit are controlled by the head pressure transducer in that circuit.  At 20°F below the leaving glycol set point both compressors are switched off and the chiller achieves 100% Free Cooling.  When either compressor is switched off, VFD control of the fans for that circuit is transferred to the leaving chilled glycol sensor, to maximize the Free Cooling effect in that circuit. At very low ambient temperatures during the Free Cooling operation, fan speed may be automatically reduced to maintain control of the glycol temperature.  At extremely low temperatures the 3-way valve at the inlet to the chiller automatically by-passes a portion of the glycol around the Free cooling coils to further insure glycol temperature control.

Motivair Free Cooling Chillers are especially well suited to Mission Critical applications (Data Centers) when they are used in conjunction with computer room AC units.  Data centers are the largest commercial users of electrical power, and therefore present the largest possible savings for any commercial HVAC applications.  Motivair Free Cooling chillers are available with environmentally friendly R-407C or R-134a refrigerants.  They are also available with acoustical treatment when lower sound levels are required.  With these options, Motivair Free Cooling Chillers are ideal for LEED points, saving the maximum energy and leave the smallest carbon footprint.

   Motivair Free Cooling Chillers – The Bottom Line $aving

                  How a 280-ton Free Cooling Chiller

                    Saves Over $114,000 per annum

This pie chart demonstrates the very significant energy savings available by using a Motivair Free Cooling Chiller for any year-round cooling application –process cooling or year-round HVAC in data centers, schools, hospitals & commercial buildings.

The temperature bin data in the chart is derived from ASHRAE 30-year historical weather data, and this data is available from Motivair for any major metropolitan area in the USA or Canada for calculating Free Cooling chiller savings.

Chicago is used here as a typical example, to demonstrate Motivair Free Cooling savings in a typical mid-western location.  The Free Cooling hours are based on assumed chilled water/glycol temperatures at ARI conditions of 54F/44F.  In this case (Chicago) the chiller will achieve partial Free Cooling (<100% Free Cooling) for approximately 881 hours which represents over 10% of the year.  However, the chiller will achieve 100% Free Cooling for 2,740 hours, which is over 31% of the year.  Therefore partial or total Free Cooling is available for over 41% of the year, which represents major potential energy and cost savings for the user.

The installed compressor power in a Motivair MLC-FC 930 (280-ton Free Cooling chiller) is 300 kW (2 x 150 kW compressors).
The average power cost in Chicago is around 12c/kWh, so a Motivair 280-ton Free Cooling chiller can save approximately: 
300 kW x 2,740 hours x $0.12 = $98,640 on full Free Cooling plus an estimated
300 kW x 881hours x 0.12 x 0.5 (conservatively assumes an average of 50% partial Free Cooling savings) = $15,858

Bottom line saving at these operating conditions will be approximately $98,640 + $15,858 = $114,498 per annum.

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