How to Choose the Right Chiller for Your Building: A Decision Guide
Every chiller decision comes down to the same handful of questions, asked in the right order. This guide walks through that decision process and links out to the detailed guide for whichever path fits your project.
Step 1: How Much Cooling Capacity Do You Need?
Start with a proper heat load calculation, not a floor-area rule of thumb. Our Chiller Tonnage & Sizing Guide walks through how to calculate this and how it maps to chiller type.
Step 2: Air-Cooled or Water-Cooled?
If water access, cooling tower space, and water treatment aren’t a constraint, water-cooled generally wins on efficiency for continuous operation. If the site can’t support a cooling tower, air-cooled keeps installation simpler. Full comparison in our Air-Cooled vs Water-Cooled Chiller guide.
Step 3: Match Compressor Type to Capacity
| Capacity range | Compressor type | Guide |
|---|---|---|
| Under ~100 TR | Scroll | Scroll Chillers Explained |
| ~100–500 TR | Screw | Screw Chillers |
| 150 TR to 1000+ TR | Centrifugal | Centrifugal Chiller |
| Medium–large, efficiency-focused | Magnetic bearing (oil-free) | Magnetic Bearing Chillers |
Screw and centrifugal overlap in the 150–500 TR range — see our direct Screw vs Centrifugal Chillers comparison if the project sits in that middle ground.
Step 4: Is the Load Constant or Highly Variable?
Buildings with fluctuating occupancy or seasonal swings benefit from variable speed drive chillers, which stay efficient across a wide load range instead of just at full load. See our Variable Speed Drive Chillers guide.
Step 5: Does the Project Need Heating as Well as Cooling?
If so, a water-to-water heat pump chiller or a compound centrifugal chiller heat pump can cover both from one plant instead of a chiller plus a separate boiler. See our Water-to-Water Heat Pump Chillers guide and Dual & Compound Centrifugal Chillers guide.
Step 6: What Redundancy Does the Facility Require?
Hospitals, data centers, and other critical facilities typically need N+1 redundancy — either multiple smaller chillers or a dual-compressor unit like the York YD, so cooling continues if one unit needs service. Hotels are a common case where several of these factors — redundancy, simultaneous heating/cooling, and variable load — combine at once; see our Chillers for Hotels guide for how that plays out.
Step 7: What’s the Facility’s Maintenance Capability?
Magnetic bearing and other oil-free technologies reduce maintenance burden significantly. If in-house maintenance capacity is limited, that’s worth weighing alongside upfront cost.
Putting It Together
Most projects land on their answer by working through these seven questions in order: capacity, cooling method, compressor type, load variability, heating requirement, redundancy, and maintenance capability. For the full picture of every chiller type before you decide, see our Types of Chillers guide.
Frequently Asked Questions
What is the first step in choosing a chiller?
The first step is calculating the building’s actual cooling load through a proper heat load calculation, which determines the tonnage the chiller needs to provide.
How do I know if I need a redundant chiller setup?
Critical facilities such as hospitals and data centers typically need N plus 1 redundancy, meaning cooling must continue even if one chiller or compressor needs servicing.
Does chiller selection depend on maintenance capability?
Yes. Facilities with limited in-house maintenance capacity often benefit from oil-free technologies like magnetic bearing chillers, which reduce ongoing servicing requirements.