Technical guide

Ice bath with chiller: the right-HP math in 5 minutes

An undersized chiller is the no. 1 reason ice baths get abandoned: 'cold-ish' 12 °C water doesn't deliver the effect and the owner gives up. The ruler is simple and it's right here - litres, HP, climate and usage - with the math worked for the three most common cases.

Technical guide · 7 min · 2026-09-28

The ruler of our line (and of physics): 1 HP ≈ 0.9 kW of cooling holds up to 260 litres at 3-5 °C in a hot climate; 2 HP up to 570 L; 4 HP up to 1,200 L. That math already bakes in tropical sun, honest insulation and daily use - it's an engineering ruler, not a shop-window one.

The three factors that move the math

Real volume: a couple's oval tub = 420 L; a barrel = 520 L; a double = 800 L. The maker's nominal volume is sometimes 'to the brim' - measure at the waterline.
Exposure: direct afternoon sun adds serious heat load; a thermal lid gives half the margin back. Shade plus a lid are worth half an HP.
Frequency of use: every body that enters is ~37 °C across 70-90 displaced litres. Back-to-back use (family, box) needs the next step up so the water returns to 5 °C between sessions.

Three solved cases

Case	Water	Usage	Verdict
Solo, compact tub on the balcony	250 L	2 sessions/day, lid on	1 HP with room to spare
Couple & friends, double tub	800 L	intense weekends	4 HP - the double needs real headroom
Crossfit box, 3 barrels	1,560 L	post-WOD queue	4 HP with a manifold - and the lid is law

What else to check on the machine

A titanium exchanger - chlorine, salt, well water: all the same, titanium takes it.
A filter in the circuit - water that circulates clean is half the maintenance.
±0.3 °C control - 'between 3 and 8 °C' on the label means 8 °C in practice.
Declared noise - an apartment balcony calls for night mode and dampers.
Spare parts in Brazil - a compressor from a known line, not a catalogue exotic.

Our chiller is built off this list - and the configurator applies the ruler for you as you build the kit.

Can I connect a chiller to a tub I already own?

Usually yes: we need the volume and two hose pass-throughs. An adapter kit solves third-party tubs - send a photo on WhatsApp.

Does a chiller burn a lot of power?

It works like a refrigerator: the compressor cycles to offset incoming heat. A lid + shade cut consumption in half; the kWh estimate for your case goes into the design.

Isn't 4 HP overkill 'just to be safe'?

It costs more standing idle and short-cycles in a small tub - wear with no benefit. Right isn't biggest: it's sized. That's what the ruler above is for.

Keep reading