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Quick answer
For a tub you already own that only needs to get cold, the Penguin Cold Plunge Chiller and Filter Kit is the pick: 7,500 BTU/hr from a 3/4 HP unit that draws just 3.9 amps, with a built-in pump and filter, rated for outdoor use above 32°F. If you want one machine that also heats (up to 104°F) and runs from an app, the Coldture Water Chiller Pro does that, but Coldture doesn't publish a BTU/hr rating, so check capacity before pairing it with a big or sunny tub. Both are sold by Sauna Marketplace. Bigger, hotter setups should look at 10,000 BTU/hr and up.
Most chiller pages lead with horsepower and the lowest temperature on the box. Neither tells you whether a chiller will hold your tub at 45°F on a July afternoon. The numbers that do are the published cooling rate in BTU/hr, the electrical draw, where the pump needs to sit, and what the maker says about heat and freezing weather. That is what this comparison uses.
Cold plunge chillers compared by published specs
| Chiller | Published cooling | Water range | Power | Best for |
|---|---|---|---|---|
| Penguin Cold Plunge Chiller and Filter Kit | 7,500 BTU/hr (3/4 HP) | Cools only; high 30s to low 40s in good conditions | 110 to 120 V, 450 W, 3.9 A | Existing tubs, indoors or outdoors above 32°F |
| Coldture Water Chiller Pro | Not published | Heats and cools, 37 to 104°F | 120 V, 8 A | Hot and cold from one unit, app control |
| Penguin 1 HP High Efficiency | 11,500 BTU/hr | Set point 37 to 100°F | 110 to 120 V, 830 W, 7.2 A | Large or hot indoor setups with an external pump |
| Ice Barrel Chiller | Not published (sold as 1/2 HP) | Cools to 37°F | About 115 V, 15 A fuse rating | Ice Barrel 300 and 500 owners |
| The Pod Company Chiller Pro | Not published (0.5 HP) | Chills to 39°F | 500 W | Small tubs, shaded or indoors |
The two to start with.
Best for most existing tubs
Penguin Cold Plunge Chiller and Filter Kit
- Cooling: 7,500 BTU/hr, 3/4 HP, R-32 refrigerant
- Power: 110 to 120 V, 450 W, 3.9 A, 10 ft GFCI-protected cord
- Pump and filter: built in
- Size and noise: 17 x 15 x 13 inches, 49 lb, 56 dBA
- Outdoors: rainproof, rated above 32°F air
- Warranty: 1 year; Penguin offers 2- and 3-year extensions
The numbers that matter line up well. A published 7,500 BTU/hr covers the holding load of a covered, insulated 100-gallon plunge with plenty left for pull-down, and it does it on 3.9 amps, so it shares a standard 15 A household circuit more comfortably than higher-draw units. Sauna Marketplace's listing says it can hold the low 40s or high 30s when the tub, weather and plumbing are in its favor. Its pump has to gravity-prime: place it within 3 feet of the tub drain, with the bottom of the chiller at or below the bottom of the tub.
Skip it if: you want a heat mode (Penguin lists none), the chiller has to sit above the tub or far from the drain, or it lives outside all winter with nowhere to drain and store it. Penguin says to disconnect and drain it at freezing.
Penguin Cold Plunge Chiller and Filter Kit at Sauna Marketplace
Best for hot and cold from one unit
Coldture Water Chiller Pro
- Range: cools to 37°F, heats to 104°F
- Power: 120 V, 8 A, standard 15 A household outlet; built-in GFCI
- Water care: continuous circulation and filtration
- Control: on-unit display and app over 2.4 GHz Wi-Fi
- Size: 24.2 x 13.1 x 18.9 inches, 66.1 lb dry
The Coldture is the choice when you want the same tub for a cold plunge in the morning and a warm soak later, or you just like setting the temperature from your phone. It heats as well as cools, it filters on a regular cycle, and Coldture's manual includes a timer function in the app. Setup is plug-in: hoses to the tub, test the built-in GFCI, power on, and the manual says it takes 2 to 3 minutes to purge air before it starts cooling or heating.
Skip it if: you need a published BTU/hr rating to size a large, bare or sunny tub. Coldture lists temperature range and power draw but no cooling rate, so ask Sauna Marketplace for capacity data first. Its 8 A draw also makes a dedicated circuit worth considering.
If you need the tub too.
A matched tub and chiller avoids the fitting, priming and placement questions entirely. Sauna Marketplace's cold plunge selection separates tub-only options from complete systems. One example: the SaunaLife S1, a 124-gallon one-person tub, comes as a package with the FDC-1A chiller and heater, rated 2.81 kW cooling (about 9,590 BTU/hr) and 3.38 kW heating, with a 32.5 to 108°F range and Wi-Fi control.
Other chillers worth comparing.
These specs come straight from the makers' pages. Sauna Marketplace doesn't carry these models, and the links carry no tracking.
- Penguin 1 HP and 1 HP High Efficiency. Rated 10,000 BTU/hr and 11,500 BTU/hr on the same 830 W and 7.2 A. Both need an external pump (Penguin recommends a Danner Mag Drive), and neither is outdoor rated. They suit a large indoor tub or a hot garage where the 3/4 HP unit would run all afternoon.
- Ice Barrel Chiller. Ice Barrel's page lists cooling to 37°F, operation in air up to 120°F, Wi-Fi app control, IP67-rated components and 65 lb. It names the Ice Barrel 300 and 500 (the 400 with a conversion kit) and other tubs with a compatible 3/4-inch hose connection. It publishes no BTU/hr rating, and its page lists both a 1-year manufacturer's warranty and a limited lifetime warranty.
- The Pod Company Chiller and Chiller Pro. Pod's specs list a 1/3 HP, 280 W standard model that chills to 41°F and a 0.5 HP, 500 W Pro that chills to 39°F, both with 20-micron filtration. Pod recommends a covered or shaded spot outdoors. No BTU/hr rating is published, so treat these as small-tub chillers.
How to choose.
Cooling rate, then everything else.
Your chiller has to beat the heat leaking into your tub on the hottest week, with room left for cooling a fresh fill. A foam-insulated, covered, shaded 100-gallon tub may leak only a few hundred BTU/hr; a bare tub in full sun can leak 5,000 or more. Work out yours with the chiller sizing guide and its calculator before you compare features.
Heat or cold only.
A heat mode lets one tub cover a warm soak, and on some systems it is also the way to keep water from freezing in winter. The Coldture heats to 104°F and the SaunaLife FDC-1A to 108°F. The Penguin Cold Therapy chiller cools only.
Winter.
Penguin's chiller is rated outdoors only above 32°F and must be drained and stored below that, and Penguin's manual says freeze damage to a chiller left outside isn't covered under warranty. Read how to keep a cold plunge from freezing before you buy for an outdoor setup in a cold climate.
Placement and the pump.
Chillers move heat into the air around them. Penguin asks for at least 12 inches of open space on all sides and says that if hot exhaust air gets pulled back into the intake, capacity is greatly reduced. Built-in pumps differ: Penguin's must gravity-prime from below the tub, while Coldture's manual describes the unit purging air on startup.
Electrical.
Check the amps. Penguin's 3/4 HP kit draws 3.9 A, the Coldture 8 A and Penguin's 1 HP units 7.2 A. Penguin recommends plugging directly into the receptacle, avoiding power strips, and using only a 12-gauge single-outlet cord if an extension is unavoidable. Coldture's manual says to test its built-in GFCI before each use.
Noise.
Penguin publishes 56 dBA for its Cold Therapy chiller. Coldture describes the Pro as low-noise without a number. If the chiller sits under a bedroom window, ask for the figure.
Water care.
A filter catches debris; it doesn't sanitize. Every chiller here still needs water treatment and changes. Use the treatment your chiller's manual specifies; Coldture's manual, for one, gives exact oxidizer and sanitizer doses. See how to keep ice bath water clean.
Check it with a real thermometer.
Penguin's troubleshooting guide says to check the water with an external thermometer, not an infrared gun, before deciding a chiller isn't keeping up. A floating wireless unit such as the GoveeLife Wireless Pool Thermometer P2 (plus or minus 0.9°F, with app alerts) also tells you when the water drifts.
FAQ
What is the best chiller for a cold plunge?
For most existing tubs, the Penguin Cold Plunge Chiller and Filter Kit: 7,500 BTU/hr on 3.9 A with a built-in pump. If you want heating and app control in the same unit, the Coldture Water Chiller Pro.
What is the best chiller for a DIY cold plunge?
One with a built-in pump and a published BTU/hr rating, placed where its pump can prime. The Penguin kit fits that, as long as it sits within 3 feet of the drain and no higher than the tub bottom.
Is a 1/2 HP chiller enough?
For an insulated, covered tub around 100 gallons out of the sun, usually. Penguin's 1/2 HP models are rated 5,000 to 5,750 BTU/hr. A bare tub in summer sun can outrun them.
Do cold plunge chillers heat as well?
Some do. The Coldture Water Chiller Pro heats to 104°F and the SaunaLife FDC-1A to 108°F; the Penguin Cold Therapy chiller cools only.
Can I leave a chiller outside in winter?
Only if its manual allows it. Penguin says to disconnect and drain its chiller when air temperatures reach freezing.
How much electricity does a cold plunge chiller use?
Multiply its watts by the hours the compressor runs. The Penguin draws 450 W, so each hour of running is 0.45 kWh; a covered, insulated tub keeps those hours short.
Can I use an aquarium or hydroponic chiller?
Only if its BTU/hr rating covers your tub's heat load and it is rated for where it will sit. Many general-purpose water chillers need a separate pump and aren't outdoor rated; Penguin's 1 HP water chillers, for example, need an external pump and are not rated for outdoor use.