The question is not whether a chiller costs more than ice to buy. It is what the tub costs to run for a year, including the labour nobody invoices.
Cooling water takes energy proportional to mass and temperature change: Q = m × c × ΔT, where c for water is about 4.186 kJ per kilogram per kelvin. Removing that heat with ice also means melting it, which absorbs about 334 kJ per kilogram at 0 °C.
| Step | Formula | Worked example: 500 L from 25 °C to 5 °C |
|---|---|---|
| Cooling energy | m × c × ΔT | 500 × 4.186 × 20 = 41,860 kJ |
| Convert to kWh | divide by 3,600 | 11.6 kWh of cooling |
| Ice needed | cooling energy ÷ (latent heat + sensible heat to target) | about 118 kg at 0 °C, before losses |
| Chiller electricity | cooling energy ÷ COP | about 4.6 kWh at COP 2.5 |
The numbers are illustrative: the ice figure assumes perfect mixing and no ambient gain, and the chiller figure assumes a coefficient of performance of 2.5, which varies with ambient temperature and model. The method is what matters.
Every bather adds heat. The room adds heat through the tub walls. An open tub loses cold to the air. Ice has to be replenished after each session; a chiller runs at part load to hold the setpoint.
That is why sizing by pull-down alone understates the job in a busy facility. The operating cost is driven by the continuous load, not by the first chill.
| Cost line | Ice | Chiller |
|---|---|---|
| Equipment | Ice machine or freezer, storage, tub | Chiller, plumbing, electrical connection |
| Energy | Ice production plus freezer standby | Compressor and pump |
| Labour | Buying, carrying, breaking and topping up ice | Periodic service |
| Water | Meltwater dilution and refills | Evaporation, backwash, filter cleaning |
| Floor | Wet floors, drainage, slip risk | Condensate drainage |
| Consistency | Temperature depends on how much ice went in | Setpoint holds automatically |
| Peak demand | Ice supply can run out on a busy day | Capacity is fixed and known |
Four inputs turn the comparison into a number: your electricity tariff per kWh, the chiller's COP or measured consumption, the local price of ice per kilogram, and the labour rate for the person handling it.
Then add sessions per week and the average bather load. A site with two sessions a day and a site with forty are not in the same argument.
Ice is the simpler answer for very low volume, one-off events, sites without a reliable power supply, or a temporary installation. A chiller is capital equipment; if the tub runs twice a month, the capital may never pay back.
The decision rule is volume. Below a few sessions a week, ice can be rational. Above that, the labour and the inconsistency usually decide it.
A supplier who can answer these four questions has a specification. A supplier who answers with horsepower alone has a headline.
Send us the tub volume, the target temperature, the ambient temperature and the sessions per week. We will return the capacity and the estimated running load, and you can put your own tariff against it.
The compressor control type decides how a chiller behaves once the tub is at temperature — how tightly it holds the setpoint and how often it starts. Here is what to put in a request for quotation, and which standards answer each question.
Read Article →Most of our chiller range can be ordered as cooling-only or as cooling-and-heating, and one model does both at once. Here is how to decide per market, and how to write the configuration into the purchase order so the right unit is built.
Read Article →
