⚡ Estimated Full-Load Demand
💰 Est. Annual Energy Cost
Sizing Breakdown
Full Calculation Table
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How to Use the Chiller Plant Calculator
Choose centrifugal, screw, scroll, or air-cooled, or select Other / Custom to enter your own efficiency and condenser flow values from a manufacturer submittal.
Enter the peak building cooling load from your load calculation, then add a distribution loss margin for pump heat gain and piping losses. Use the commercial load calculator if you have not sized this yet.
Enter your design supply and return chilled water temperatures. A 6C temperature difference is standard for most Canadian commercial systems.
Click Calculate Chiller Sizing to see total tonnage, chilled and condenser water flow, per-chiller sizing, and estimated electrical demand and annual energy cost.
Understanding Chiller Plant Sizing
A chiller plant converts building cooling load into a chilled water supply that AHUs and fan coils use to condition zones. Sizing the plant correctly starts with an accurate building cooling load, then works through tonnage, water flow rates, and equipment count before the mechanical designer selects specific chiller models from manufacturer submittals.
From Building Load to Tons of Refrigeration
One ton of refrigeration equals 3.517 kW, a unit that traces back to the cooling effect of melting one ton of ice over 24 hours. Once you have the building peak cooling load in kW, add a distribution loss margin for pump heat gain and piping losses, then divide by 3.517 to get total plant tonnage. A well-insulated distribution system typically adds 2 to 5 percent, while longer runs or poorly insulated piping can push that closer to 8 to 10 percent.
Chilled Water Flow and Temperature Difference
Chilled water flow rate depends on both the cooling load and the temperature difference between supply and return water. A wider temperature difference reduces flow rate and pump energy but can affect coil selection and dehumidification performance downstream. Most Canadian commercial systems use a 5.5 to 6.5C temperature difference, commonly rounded to a 6C delta T for preliminary sizing, and that flow figure is what feeds directly into the hydronic pipe sizing calculator for the distribution side.
Condenser Water and Air-Cooled Alternatives
Water-cooled chillers reject heat through a condenser water loop connected to a cooling tower, which is generally more efficient than air-cooled rejection but requires tower maintenance, water treatment, and compliance with CSA B52 for the refrigeration system. Air-cooled chillers reject heat directly to outdoor air through integral condenser coils, trading some efficiency for a simpler mechanical room and no cooling tower. The cooling tower calculator sizes the tower side of a water-cooled plant once you know condenser water flow from this tool.
Why Most Plants Use More Than One Chiller
Chillers spend the vast majority of the year running well below their peak design tonnage, since Canadian buildings rarely see extreme summer design conditions for more than a handful of days annually. Splitting total tonnage across two or more smaller chillers lets the plant run one unit efficiently at partial load instead of cycling a single oversized chiller on and off. It also provides redundancy, since a single-chiller plant loses all cooling capacity if that unit needs service. Most Canadian commercial plants above roughly 200 tons use two or more chillers for this reason.
IPLV, Full-Load Efficiency, and Real Operating Cost
Full-load efficiency, measured in kW per ton, describes performance only at the single hottest design condition. IPLV weights efficiency across a standardized set of part-load conditions that better reflect how the chiller actually runs across a Canadian cooling season. Two chillers with similar full-load kW per ton ratings can have meaningfully different IPLV numbers and different real annual operating costs, a gap worth running through the annual energy cost calculator before treating two quotes as equivalent. This calculator's estimate uses full-load efficiency by chiller type as a starting point; confirm IPLV against the manufacturer's selection software for final energy modeling.
Halocarbon Regulations and Refrigerant Selection
Canadian chiller plants fall under SOR/2016-137, the federal Ozone-depleting Substances and Halocarbon Alternatives Regulations, and provincial mechanical codes that reference CSA B52. The Kigali Amendment phase-down schedule is steadily reducing high-GWP HFC refrigerant availability, which is pushing new chiller selections toward lower-GWP options. Confirm current refrigerant availability and any provincial reporting requirements with your mechanical contractor before finalizing a chiller order.
Frequently Asked Questions
One ton of refrigeration equals 3.517 kW of cooling capacity. Divide the total building cooling load in kW by 3.517 to get the required tonnage, then add a safety margin for pump heat gain and piping losses between the plant and the zones it serves, typically 2 to 5 percent for a well-insulated distribution system. Get your building load from the commercial load calculator if you have not already sized it.
Chilled water flow rate in litres per second equals the cooling load in kW divided by 4.186 times the chilled water temperature difference in degrees Celsius. A standard Canadian commercial design uses a 5.5 to 6.5 degree Celsius temperature difference between supply and return chilled water, commonly written as a 6C delta T.
Integrated Part Load Value (IPLV) is a weighted average efficiency rating that reflects how a chiller performs across a range of part-load conditions rather than only at full design load, since chillers spend most of the year running below peak capacity. A chiller with a strong IPLV rating typically uses less annual energy than one selected purely on full-load efficiency, even if the full-load numbers look similar on paper.
Most Canadian commercial plants above roughly 200 tons use two or more chillers rather than one large unit, which allows the plant to run efficiently at partial building load and provides redundancy if one chiller needs service. A common approach splits total tonnage across two equally sized chillers, or uses one larger lead chiller with a smaller lag chiller for shoulder-season loads. See the district cooling calculator if your building connects to a shared plant instead of operating its own chillers.
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