Cold Plunge Chillers Explained: How They Work and What to Compare

This guide explains how a chiller works, what to compare, and what each chiller we sell does, using the manufacturers' specifications and our prices as of October 15, 2026. Sources are listed at the end. For the tubs themselves, see our guide to the best cold plunge tubs.

How a chiller works

A chiller works like a small air conditioner for water. A pump draws water from the tub through hoses, a refrigeration circuit inside the unit takes the heat out, and a fan blows that heat into the air around it. The cold water flows back into the tub, and the chiller switches on and off to hold your set temperature.

The chillers we sell also run in reverse as a heater, so the same tub can be a warm soak. Most also pass the water through a filter and a sanitizer every time it circulates.

Chiller or ice?

Ice works, but it adds up. Melting ice soaks up about 144 BTU per pound, plus a little more as the meltwater warms. By that math, cooling a full tub from 65°F hose water to 50°F takes about:

That is before the sun and air warm the water back up, and the melted ice raises the water level each time. Ice makes sense for an occasional plunge. If you plunge most days, a chiller does the same job at the touch of a button.

Every chiller we sell, compared

We don't sell chillers on their own. Each one comes with a tub, either built in or as part of a package:

Cooling power is how much heat a chiller can pull out of the water each hour. One kilowatt of cooling is about 3,412 BTU per hour. Only Icetubs gives a horsepower figure.

How cold do you need it?

Less cold than the spec sheets suggest. Cleveland Clinic advises against going below 40°F and suggests 50 to 59°F for beginners. Every chiller above reaches that range, so a lower bottom number shouldn't decide your purchase on its own. Cooling power and tub size matter more, because they decide how quickly the water gets cold and how well it holds there on a hot day.

How long it takes to get cold

Icetubs is the only maker we carry that publishes a cooling rate: about 3°C (about 5°F) an hour, depending on conditions. At that rate, water from a 68°F hose takes five to six hours to reach the high 30s. The other brands don't publish a figure.

Plan on the first cool-down taking most of a day. After that the chiller only has to hold the temperature, which is much easier. Three things help it:

• Keep the cover on. Kohler says to put the cover back after every use to keep the water clean and help efficiency.
• Find shade. Sun on the tub and the chiller makes it work harder.
• Keep the vents clear. The chiller has to get rid of the heat it removes. Kohler warns that blocked vents affect performance, and Icetubs says the area should be well ventilated.

Power and wiring

Every chiller we sell runs on 120V. None needs 240V. What differs is the circuit:

• Kohler Ice Bath: its own 120V, 20-amp circuit with Class A GFCI protection.
• Icetubs: draws up to 14.5 amps, almost all of a 15-amp circuit, so keep other big loads off it. The power cable and breaker are water-resistant, not waterproof, so protect them from rain outdoors.
• SaunaLife: GFCI protection is built into the power cord.

The National Electrical Code requires GFCI protection on outlets that feed a spa or hot tub, and your local inspector decides how that applies to a cold plunge. Have a licensed electrician check the outlet and where it sits.

Outdoor temperatures

A chiller is rated for a range of outdoor air temperatures, and it matters most if you live somewhere hot or plan to plunge through the winter:

• SaunaLife FDC-1A (S1 packages): 59 to 109°F for cooling, 59 to 95°F for heating.
• SaunaLife AP-1 (S2 packages): 32 to 113°F.
• Icetubs: drain the engine if it is running below 23°F or above 104°F, and bring it indoors if it is switched off below 33.8°F or above 104°F.
• Kohler: when the air drops below 40°F, the Ice Bath heats the water on its own to keep it from freezing.

If you want to plunge outside through a cold winter, the AP-1, Icetubs and Kohler are rated for colder air than the FDC-1A.

Keeping the water clean

The chiller's filter and sanitizer let you keep the same water for weeks instead of refilling after every few plunges:

• Sanitizing: SaunaLife, Finnmark and Icetubs use ozone. Kohler uses UV light.
• Filters: SoulCold uses a 20-micron filter, Kohler a 30-micron filter, and Icetubs says its filters catch particles as small as 5 microns.
• How often: Kohler says to replace the filter every month and the water every 1 to 2 months. Icetubs says to change the filters monthly and, with one person plunging daily, the water every 1 to 2 months.

We stock Icetubs replacement filters ($275 for six), Finnmark carbon filters for the SoulCold ($37.50 for four) and Finnmark 5-inch pleated chiller filters ($18.75 for four).

What it costs to run

Only Icetubs publishes the power a chiller uses: 1.35 kW. At the U.S. average residential rate of 18.31 cents per kWh (EIA, July 2026), that is about 25 cents for every hour the engine runs. A chiller doesn't run all day once the water is cold, so your bill depends on how hot it is outside, how often the cover comes off, and how cold you keep it.

Which setup should you buy?

• Lowest price with a chiller: the SaunaLife S1NC package at $5,340, with the FDC-1A, which shares the widest temperature range we carry (32.5 to 108°F) with the SoulCold. Add the $390 cover and $695 delivery.
• Everything included: the Finnmark SoulCold at $6,990, with its chiller, cover and free delivery.
• Room for two: the SaunaLife S2NC package at $7,120, with the more powerful AP-1, which is also rated for colder air.
• Indoors and compact: the Icetubs IceBarrel at $9,995, with the engine, cover and filters included.

Already own a tub? We don't list chillers on their own, but the SaunaLife tub-only models have 3/4-inch chiller connections built in. Call us and we'll check with the manufacturer what fits. Or browse every cold plunge tub and the covers and filters that go with them.