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Every espresso machine that steams milk has the same problem to solve. Brewing wants water a little under boiling, around 90 to 96°C (195 to 205°F). Steaming milk wants a lot more heat than that. How a machine handles the two jobs decides how fast you can make a milk drink, and a big part of what you pay.
There are four main designs. For someone who drinks cortados, the right one is often cheaper than you’d think, because a cortado uses so little milk.
Flow-Through Heaters
Thermoblocks, thermocoils and Breville’s ThermoJet heat water on demand as it runs through a heated block or pipe. They warm up in seconds, which is their big advantage, and they’re limited by how much power the element can put out. Most machines under about $700 work this way, including the Breville Bambino ($249.95 to $299.95), the Bambino Plus ($399.95 to $499.95) and the Barista Express, which uses a thermocoil ($499.95 on sale, $699.95 list).
Single Boiler
One boiler, one heating element and two thermostats, one for brewing and one for steam. You can’t do both at once. You pull the shot, flip a switch, wait for the boiler to reach steam temperature and then steam your milk. For one or two drinks that’s fine. For a queue of lattes it’s slow. The Gaggia Classic E24 ($499 to $549) and the Rancilio Silvia ($995, or about $1,199 with a PID controller) are the standard examples.
Heat Exchanger
A heat exchanger, or HX, machine keeps one large boiler at steam temperature and runs the brewing water through a tube inside it, so the water heats on its way to the group. You can brew and steam at the same time. The catch is temperature. A traditional HX drifts by 5 to 10°F at idle and needs a cooling flush before the shot, though newer HX machines with PID control hold within about 1°F. Around $2,000 buys a good one, such as the Lelit MaraX3 ($1,999.95, on sale in the US since July 2026) or the Profitec Pro 500 PID ($1,999).
Dual Boiler
Two boilers, one for brewing and one for steam, usually each with its own PID. You get steady brew temperature and full steam at the same time. It’s the most convenient design and usually the most expensive: the Gaggia Classic GT ($1,529 to $1,699), the Breville Dual Boiler ($1,599.95), the Rancilio Silvia Pro X ($2,195), the Profitec Pro 600 ($2,399) and the Lelit Bianca V3 ($2,999.95).
| Design | Brew and steam at once? | Typical US price, September 2026 | Best for |
|---|---|---|---|
| Flow-through | No, but most switch to steam quickly | About $250 to $700 | One or two small milk drinks |
| Single boiler | No | About $450 to $1,200 | A drink or two, and people who like to tinker |
| Heat exchanger | Yes | About $2,000 | Back-to-back milk drinks |
| Dual boiler | Yes | About $1,500 to $3,000 | Busy households who want control |
What a Cortado Drinker Needs
Here’s what the spec sheets skip. A cortado takes about 60 ml of milk, and a 12-ounce latte takes about five times as much. Steaming power matters most when you’re heating a lot of milk over and over, which is exactly what a cortado drinker doesn’t do. One person making a cortado or two a day will be happy with a flow-through machine or a single boiler. A household making four milk drinks at the same time every morning is where heat exchangers and dual boilers earn their price.
Spend what you save on a good grinder. It will do more for your cortado than a second boiler will. And whichever machine you end up with, our cortado recipe covers the milk technique.