Brand satisfaction score is based on how satisfied 2724 surveyed members are with their coffee machines from a scale of excellent to terrible (survey conducted in 2019). Not all brands have scores as we require a minimum of 50 responses per brand.
Brand reliability scores are based on responses from more than 2700 coffee machine owners in 2019. We ask whether they have run into a problem with their appliance in the last 12 months. Scores are based on brand, not model. Not all brands have scores as we require a minimum of 50 responses per brand.
Three experts test the espressos in a 'blind' tasting, checking the colour and thickness of the crema (the tan-coloured foam on the top of an espresso), aroma, flavour, mouth-feel (for example, creaminess or wateriness) and aftertaste.
We experiment with each machine to find how it best froths milk, looking for fine, pourable froth. We use what the manufacturer recommends (a milk frother, milk-based capsule or coffee capsule extracted over milk).
Thermoblock heats up only a very small quantity of water on demand as it flows through the system. The capacity of the water can be as little as 10mL; the larger ones can heat up to 50mL at a time.
Models with boilers heat a larger amount of water and keep it heated fairly consistently. For example, the Rancilio has a 300mL capacity, which is heated all at once and then maintained at that heat. A dual boiler includes two boilers; one for making coffee and one for steaming, which saves time as you don't have to switch modes.
Heat exchanger models are used a lot in commercial scenarios. They use a single boiler but are designed to produce coffee and steam at the same time. The boiler produces steam, while a pipe running water through the boiler is heated on the fly to the right temperature.
The pressure the pump exerts when pushing hot water through the ground beans; measurement given in 'bar'. Some trial and error with the pressure and grind is required. A high bar does not necessarily mean a superior machine. We optimise the machines before giving them a taste test to give them their best chance.