Hot side: compressor → condenser → drier, high pressure (about 5.3 bar)Cold side: capillary → cold plate → suction line, low pressure (about 0.6 bar)Thermometer needle: the air the food sits inA 130-litre under-counter fridge running on isobutane (R600a). The compressor squeezes the vapour to about 5.3 bar, where isobutane condenses at around 40 °C, well above the kitchen's 22 °C, so the coil on the back sheds heat into the room and the hot gas turns to liquid. The capillary tube is the fridge's expansion valve: a 0.7 mm bore, metres long, that lets the liquid through but holds back the pressure, so it leaves at about 0.6 bar, where isobutane boils at −24 °C. Boiling in the cold plate, it soaks heat out of the air and the food, and the suction line carries the vapour back to start again. The thermostat starts the compressor when the cabinet warms 1 °C above the dial's setting and stops it 1 °C below; with about 22 W leaking in through the foam it runs roughly a third of the time. Time here runs 150 times faster than life.