Tonnage is the nominal capacity of an air conditioner or heat pump. One ton equals 12,000 BTUs of heat moved per hour, the cooling effect of melting one ton of ice over a day. Residential systems typically range from about 1.5 to 5 tons, and the correct size comes from a room-by-room heat-loss and heat-gain calculation.
Why it matters to you
In the heating-dominated Fraser Valley, a heat pump is usually sized around winter heat loss, not summer cooling. An oversized system short-cycles, wears out early and never reaches its rated efficiency, while an undersized one leans heavily on backup heat during cold snaps.
Practical guidance
Ask every bidder how they sized the system; a written heat-loss calculation beats a square-footage rule of thumb or simply matching the old unit. Compare quotes at the same capacity, and check that the ductwork can carry the airflow that capacity needs.