calcs.homes
calcs.homes
Enter your home's conditioned area, climate, ceiling height, and insulation, and this heat pump size calculator estimates the system size in tons plus a rough backup-heat figure for cold spells.
Estimate only — cold-climate heat pump sizing balances heating and cooling loads and needs a Manual J.
A heat pump does both jobs, so it is normally sized to the cooling load and then checked against the heating load. We estimate the cooling load from area, climate, ceiling height, and insulation, divide by 12,000 for tons, and round to the nearest half ton. The backup-heat figure is a rough gap between the home's cold-weather heat demand and what the heat pump delivers before its capacity fades — a placeholder for the electric strip or furnace that carries the coldest hours.
In mild climates the cooling load governs and a standard heat pump is fine. In cold climates the heating load is larger, and the honest answer is a cold-climate (hyper-heat) model chosen with a Manual J that plots capacity against your design temperature. Oversizing to cover cold snaps ruins summer humidity control, so backup heat is usually the better trade.
About 2.5–3.5 tons for cooling in most climates. Cold-climate heating may need a hyper-heat model of similar tonnage plus backup heat for the coldest days.
Size to the cooling load in mild and moderate climates. In cold climates, use a cold-climate unit sized with a load calculation and add backup heat rather than oversizing.
Usually some backup: electric resistance strips in the air handler, or a dual-fuel gas furnace. It covers defrost cycles and the hours below the heat pump's effective range.