A standard American washer is 27 inches wide and a standard dryer is 27 to 29. A Beacon Hill pantry, a North End galley kitchen, a South End parlour-floor closet and a Back Bay bathroom alcove are frequently not 27 inches of anything. So the laundry that got installed in these buildings is compact: 24-inch European-format machines, or a stacked pair, or an all-in-one washer-dryer combination.
They are good machines. They also fail differently from the 27-inch equipment most repair advice is written about, and they are much harder to get at.
The three formats and what they actually are
24-inch front-loaders. Bosch, Miele, Asko, Blomberg, and compact lines from LG and others. Smaller drum, longer cycles, generally excellent build. Many have a built-in water softener with a salt reservoir — turn that setting to its lowest value on MWRA water, which is already very soft.