The best cold plunge chiller for the money

How we judged value here

Three criteria, applied in this order:

1. Three-year electricity, computed from the published wattage. Same rate, same assumed hours, for every unit. No estimates.
2. Whether it publishes enough to be judged at all. A chiller with no published draw cannot be costed, and we will not guess one.
3. What the money also buys. Gallon rating, cooling floor, filtration type and warranty - because the cheapest running cost is a bad deal if the unit is too small for your tub.

The three-year electricity table

Computed at 18.34 cents per kWh, at six hours a day for three years. Six hours is an illustration, not a measurement - it is the same illustration for every row, which is what makes the column comparable.

Read the first and third rows together. The difference between a 190 W chiller and a 600 W chiller is about $494 over three years. The difference between a 280 W unit and a 1,200 W unit is about $1,109. Now look at the live prices in the table above: in this category those electricity gaps are usually larger than the price gaps they sit behind, which is the whole argument of this page. We do not print prices in copy - they move, and the figures beside each pick are the live ones - so do that comparison with the numbers on screen rather than a number we typed months ago.

Why the cheapest sticker is usually the worst deal

The 600 W and 1,200 W units in this roundup tend to carry the lower purchase prices, and the 190 W and 280 W units the higher ones. That is not a coincidence: a more efficient compressor and a better heat exchanger cost more to build. What the listing never does is put the two numbers next to each other, so the buyer compares prices and ignores a running cost that is several hundred dollars over the life of the unit.

This is the same argument we make for tubs in best cold plunge for the money, except that with a chiller the ongoing cost is far larger, because a chiller runs for hours rather than minutes. The full category table is on what a chiller costs to run.

The two you cannot judge at all

Two chillers on this site publish no rated wattage. One of them is in the list above, and it is there deliberately rather than quietly omitted: it is a perfectly normal-looking listing at a normal-looking price, and there is no way to work out what owning it costs. Both computed cost components score zero for it, which is why it ranks last here.

That is not a claim the unit is inefficient. It might be excellent. It is a statement that the seller has not given you the one number that decides the largest ongoing cost of the purchase, and that on a page about value, an unknown is a mark against.

Value is not only electricity

Two things can undo a good running cost:

• Undersizing. A cheap-to-run chiller matched to a tub larger than its published gallon rating will run continuously and never reach setpoint, which costs more than the right unit would have. How to size a chiller has the bands.
• Consumables. A cartridge filter is a recurring purchase; a rinsable metal mesh is not. Over three years that difference is real money that never appears in a price comparison - which chillers publish their filtration sets out who uses which.

Duty cycle: the uncertainty that does not change the answer

A chiller does not draw its rated power continuously. It runs until the water reaches setpoint, then cycles to hold it, and how much of each hour that takes depends on four things no listing publishes: how well the tub is insulated, whether the lid is on, how warm the room is, and how far below ambient you are asking the water to sit. A well-insulated, covered tub in a cool garage might hold at a fraction of full draw; an uncovered tub on a hot patio might run almost continuously.

That is a real limit on what anyone can tell you about absolute cost, and it is why the table above is labelled as a ceiling. What it does not do is disturb the ranking. Duty cycle is a multiplier that applies to every unit in the same conditions, so if a 190 W chiller and a 600 W chiller are both cycling at forty percent in your garage, the 600 W unit still costs roughly three times as much to hold the same water. The ratio is the durable finding; the dollar figure is the illustration.

The one case where that breaks down is undersizing. A chiller too small for its tub never reaches setpoint, so it never gets to cycle - it runs at full draw indefinitely, which is the one way a cheap-to-run unit becomes the expensive one. That is the practical reason sizing and value are the same question.

Buying more chiller than the tub needs

The opposite error is quieter and more common. Published gallon ratings across the chillers on this site run from about 79 to 230 gallons, and the instinct when in doubt is to buy up. On a tub well inside a unit’s rating the compressor reaches setpoint sooner and then cycles, so the penalty is not as large as the wattage difference suggests - but you have still paid for capacity you are not using, and on a 1,200 W unit you are paying the higher rated draw every hour it does run.

The honest rule is to match the published rating to your measured volume with modest headroom, and to add a band only if the tub lives somewhere unconditioned. A chiller sized two bands up is not insurance; it is a higher purchase price and a higher ceiling on the running cost.

Check the arithmetic yourself

Nothing on this page needs to be taken on trust. The formula is:

kWh  = watts / 1000 x hours
cost = kWh x your rate per kWh

So a 600 W chiller running six hours is 3.6 kWh, and at 18.34 cents per kWh that is about 66 cents a day, or roughly $241 a year. Substitute your own tariff from your own bill and the ranking will not move, because every unit is multiplied by the same number. Our full method, including the source and date of the rate we use, is on the methodology page.

One more line item belongs in a value judgment and never appears in a price comparison: what happens when the unit fails. Three of the five picks here publish a warranty term and the other two publish nothing at all, and on a sealed refrigeration system a failure outside warranty is usually a replacement rather than a repair. A published term is not a guarantee of quality, but an unpublished one tells you the seller was not willing to commit to a number, which on a purchase you expect to run for years is part of the price.

What we would buy

If your tub is at or under the published rating of a low-wattage unit, buy the low-wattage unit and accept the higher sticker: over three years it is the cheaper object, and the arithmetic above is the reason. If your tub is large enough to need a half-horsepower or full-horsepower chiller, then the running cost is simply the price of cooling that much water - but buy the one that publishes its draw, so you know what you have agreed to.

And if you are still deciding between a chiller and bags of ice, the break-even is worked through here with the formula rather than a headline figure.