Commercial buildings
Offices, hotels, hospitals and malls with cooling loads in the hundreds of tons.
Ebara screw chillers
Screw chillers
Reliable, efficient water-cooled chillers for commercial buildings and industry. Ebara screw chillers from 100 – 600 RT, with dual independent circuits and chilled fluid down to −20 °C.
- 100 – 600 RT
- Dual independent circuits
- Chilled fluid −20 °C to 35 °C
- Ebara, Japan · since 1912
The basics
What is a screw chiller?
A screw chiller is an electric water chiller built around a rotary screw compressor: two meshing helical rotors that trap refrigerant vapour and squeeze it into a smaller and smaller space as they turn. It is a positive-displacement machine, like a piston compressor, but with smooth, continuous rotation and few moving parts.
Screw compressors cope well with high pressure lifts and low loads. That makes them a strong choice for small and medium chilled-water plants, process cooling and low-temperature duties such as glycol or brine cooling.
Ebara screw chillers have two compressors, two condensers, two evaporators and two drives, arranged as independent circuits. If one side needs service, the other keeps cooling.
How it works
Two rotors, continuous compression
A screw chiller uses the standard refrigeration cycle. The screw compressor is what makes it robust and flexible.
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01
Suction
Low-pressure refrigerant vapour from the evaporator enters the pockets between the two rotors.
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02
Compression
As the rotors turn, each pocket shrinks and moves along the rotors, squeezing the vapour to high pressure.
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03
Condensing
The hot vapour condenses in the water-cooled condenser, handing its heat to the cooling-tower water.
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04
Expansion and evaporation
The liquid expands to low pressure and boils in the flooded evaporator, chilling the water or glycol that serves your building or process.
Capacity control: an inverter drive changes compressor speed to follow the load. That keeps efficiency high at part load and gives a smooth start without a large current spike.
Applications
Where screw chillers work best
Robust compressors and redundant circuits make screw chillers a dependable choice across buildings and industry.
Process cooling
Plastics, pharmaceuticals, food and chemicals, where chilled water must be available around the clock.
Low-temperature duty
With glycol or brine, Ebara screw chillers deliver fluid as cold as −20 °C for cold storage and process applications.
Critical loads
Two independent circuits give built-in redundancy for hospitals, data rooms and continuous production.
Long running hours
Designed for plants that run day and night, with dual compressors sharing the duty.
Plant upgrades
Replacing older, less efficient chillers in existing plant rooms to cut energy use.
Screw vs centrifugal
Which compressor suits your plant?
Both are efficient water-cooled chillers. The deciding factors are size, load pattern and the water temperature you need.
| Property | Screw | Centrifugal |
|---|---|---|
| Compressor | Positive displacement: two meshing rotors | Dynamic: a high-speed impeller |
| Ebara capacity range | 100 – 600 RT | 150 – 3,200 RT |
| Best suited to | Small to medium plants, process cooling and high-lift duties | Large plants with high, steady loads |
| At low load | Handles low load and high lift comfortably | Needs good controls to avoid surge; variable speed helps |
| Lowest leaving fluid (Ebara) | −20 °C | −10 °C |
| US DOE (FEMP) full-load requirement, 300 tons and above | About 0.56–0.59 kW/ton | About 0.50–0.54 kW/ton |
Efficiency figures are the US Department of Energy FEMP purchasing requirements for water-cooled chillers (Path A, full-load optimised). Lower kW/ton is better; COP = 3.517 ÷ kW/ton.
Is it right for you?
When a screw chiller makes sense
A strong fit when…
- Your load is roughly 100 – 600 RT, or you are splitting a larger load across several chillers
- You need reliable cooling around the clock with built-in redundancy
- You need chilled glycol or brine below 0 °C for process cooling
- Your cooling load varies widely through the day or the year
Consider another type when…
- Each chiller must deliver well over 600 RT: centrifugal chillers are usually more efficient at that size
- There is no space or water for a cooling tower: air-cooled chillers avoid it
- You have waste heat or steam available: an absorption chiller can cut electricity use
Alternatives we supply:
Why Ebara
Built for continuous duty
Founded by Mr. Issey Hatakeyama in 1912, Ebara has manufactured fluid and HVAC machinery for more than 100 years to AHRI, JIS, ASME, ISO and CTI standards, with factories in Japan, China and Thailand under Japanese supervision.
- Asia's first centrifugal chiller
- 1929
- First absorption chiller
- 1962
- Installed in Pakistan
- 20,000+ TR
Built into Ebara screw chillers
- AHRI-certified models & selection software
- Dual compressors, condensers, evaporators & VFDs
- Inverter-driven compressors
- Flooded heat exchanger design
- ASME-approved evaporator & condenser
Planning a project
What to consider before you buy
Getting these right at design stage keeps the plant efficient and dependable for its whole life.
Size to the real load
Accurate load calculations, and splitting capacity between two or more chillers, keep machines in their efficient range and provide standby.
Glycol or brine systems
For fluid temperatures near or below 0 °C, water needs glycol or brine. Its concentration affects pump and heat-exchanger sizing, so fix the leaving temperature early.
Cooling tower and water treatment
Condenser water temperature and tube cleanliness drive efficiency. Size the tower correctly and keep its water treated.
Electrical supply
Inverter-driven compressors start smoothly, which reduces the starting current your transformer or generator must supply.
Compare part-load efficiency
If the chiller will run mostly at part load, compare IPLV as well as full-load kW/ton. US DOE guidance separates chillers optimised for full load from those optimised for part load.
Maintenance
Regular oil and refrigerant analysis, tube cleaning and control checks keep a screw chiller efficient. Dual circuits let you service one side while the other keeps running.
FAQ
Screw chillers: common questions
Can’t find your answer? Ask our engineers.
What is a screw chiller?
An electric water chiller that uses a rotary screw compressor, two meshing helical rotors, to compress refrigerant. It is robust, handles high pressure lifts and low loads well, and suits small to medium plants and process cooling.
What capacities are available?
Ebara water-cooled screw chillers range from 100 – 600 RT. Larger plants combine several chillers, which also provides standby capacity.
Screw or centrifugal chiller: which should I choose?
For large plants with steady loads, centrifugal chillers are usually the most efficient. For smaller plants, widely varying loads, high-lift conditions or low-temperature process cooling, screw chillers are often the better fit.
How cold can a screw chiller go?
Ebara screw chillers can deliver leaving fluid from −20 °C to 35 °C. Below about 0 °C the circuit must use glycol or brine instead of plain water.
What are dual independent circuits?
The chiller has two separate refrigerant circuits, each with its own compressor, condenser, evaporator and drive. If one circuit stops for a fault or service, the other keeps producing cooling.
Why is an inverter drive useful?
It varies compressor speed to match the load, which improves part-load efficiency, and it starts the motor gently, avoiding the high current of a direct start.
Does a water-cooled screw chiller need a cooling tower?
Yes. It rejects heat through condenser water, usually from a cooling tower. We size and supply the towers, pumps and piping together with the chillers.
What maintenance does a screw chiller need?
Periodic oil and refrigerant checks, condenser tube cleaning, inspection of electrical and control components, and cooling-tower water treatment. Our after-sales team provides this service.
Get a selection
Need reliable process or comfort cooling?
Tell us your cooling load, required water temperature and operating hours. Our engineers will select the right Ebara screw chillers and size the cooling towers and pumps to match.