Compare industrial chiller quotations at the same leaving-fluid temperature, ambient condition, fluid composition and flow requirement. Then compare electrical demand and the equipment included in the price. Two machines described with the same nominal tonnage can deliver different usable cooling at your process conditions.
The practical starting point is a duty schedule sent to every supplier. It turns a collection of catalogue ratings into comparable selections and exposes differences before pumps, pipework and electrical services are ordered.
Why the nominal capacity is only a starting point
A chiller's nominal tonnage is a size description rather than a promise of the same output at every temperature. Lower fluid temperatures or more demanding heat-rejection conditions can change the available capacity. Daikin Applied explains the distinction between nominal and actual chiller tonnage. The useful quotation states the selected capacity at the conditions of your installation.
For example, a quotation based on chilled water and one based on a glycol mixture are not yet comparable, even if both show the same headline capacity. Ask both suppliers to select against the same fluid type and concentration. Do not apply a correction factor copied from a different machine.
Put these conditions on the comparison sheet
| Item | Use the same basis | What to compare in the reply |
|---|---|---|
| Process load | Required heat removal and expected load range | Available cooling at the specified duty, plus the basis for any reserve |
| Fluid temperatures | Required supply and expected return temperatures, with measurement locations | Selection temperatures and achievable control range |
| Ambient or condenser conditions | Design entering air for an air-cooled unit, or condenser-water conditions for a water-cooled unit | Capacity and operating limits at those conditions |
| Fluid | Water or specified glycol mixture and concentration | Compatible wetted materials and selection corrections |
| Hydraulic duty | Required process flow and external circuit resistance | Pump duty and available pressure at the stated flow |
| Electrical supply | Site voltage, phase and frequency | Selected input power and electrical installation requirements |
| Supply boundary | Required pump, tank, controls, accessories and documentation | Included items, exclusions and site responsibilities |
Flow and pressure deserve the same attention as cooling capacity. A unit that removes enough heat still needs to circulate fluid through the process at the required duty. PolyScience's chiller selection guidance identifies coolant temperature, heat load, flow/pressure and heat rejection as separate selection factors. Its guidance also distinguishes the temperature required at the process from conditions at the chiller.
Keep cooling output and electricity on separate lines
Cooling capacity in kW describes heat removal. Electrical input in kW describes power consumed. They use the same unit but measure different things. An offer that lists only one kW value leaves an important ambiguity.
For a running-cost comparison, ask each supplier to identify what its input figure includes: the refrigeration unit, condenser fans, integral pump or other auxiliaries. Compare the same boundary at the same load and conditions. A full-load point is useful for that point; it is not by itself an annual energy forecast.
If a supplier presents a seasonal or part-load efficiency metric, retain its test basis alongside it. Do not rank it against a single operating-point ratio as though they describe the same duty. For a process with long periods at a low load, request selected performance at representative loads as well as the design maximum.
Check the quiet part of the production cycle
The largest load may occur during a short production step, while the chiller spends much of the day serving a smaller load. Include that pattern in the enquiry. Ask about the minimum controllable load, required system water volume and the proposed control sequence, rather than adding capacity without a reason.
A buffer vessel can increase the thermal inertia of a short water circuit and reduce compressor cycling. Trane's explanation of its CGAM buffer-tank option illustrates that function. It does not establish a universal tank size for other chillers. Tank volume, connections and the space it occupies must follow the selected equipment and circuit.
A lower equipment price can leave a larger site package
Read the inclusions against the installation drawing. A pump may be offered, yet the quoted duty may not include the resistance of your external pipework. A cabinet dimension may be shown, yet the required service and ventilation spaces still need allocation. Remote controls may be available, yet the specific interface and responsibility for connecting it may remain outside the offer.
A useful commercial comparison therefore has two totals: the quoted supply and the remaining work needed to make that supply usable. Record the evidence still required before ordering, such as the selected performance sheet, connection drawing and electrical schedule. This is more actionable than a long list of optional features without a defined supply scope.
For equipment options, see air-cooled chillers; for the connections around the unit, see air-cooled chiller systems. shengtongJH coordinates equipment and materials sourcing against the agreed requirement. Send the operating conditions, load pattern and supply scope to discuss a configuration suited to your installation.