What size heat pump?
A rough bracket for a coastal BC home, so you can sanity-check a quote before you sign it. No email required — and read the part about oversizing, because it is the mistake that costs people the most.
Four questions about the home
Typical heating loads at a standard ceiling height
Nominal capacity in tons, for whole-home heating on the BC coast. One ton is 12,000 BTU per hour. On the coast heating governs the sizing; cooling needs are usually lower.
| Floor area | Before 1960 | 1960–1990 | After 1990 | High performance |
|---|---|---|---|---|
| 800 sq ft | 2.0 – 2.3 | 1.7 – 2.0 | 1.3 – 1.7 | 1.3 – 1.7 |
| 1,200 sq ft | 3.0 – 3.5 | 2.5 – 3.0 | 2.0 – 2.5 | 2.0 – 2.5 |
| 1,600 sq ft | 4.0 – 4.7 | 3.3 – 4.0 | 2.7 – 3.3 | 2.7 – 3.3 |
| 2,000 sq ft | 5.0 – 5.8 | 4.2 – 5.0 | 3.3 – 4.2 | 3.3 – 4.2 |
| 2,500 sq ft | 6.3 – 7.3 | 5.2 – 6.3 | 4.2 – 5.2 | 4.2 – 5.2 |
| 3,000 sq ft | 7.5 – 8.8 | 6.3 – 7.5 | 5.0 – 6.3 | 5.0 – 6.3 |
Bigger is not safer
The instinct is to round up. With a heat pump that is the wrong instinct, and it is the most common sizing mistake we are called out to.
An oversized system reaches the thermostat setpoint quickly and shuts off, then starts again a few minutes later. That short cycling means:
- Rooms that feel draughty and uneven, never settled
- Poor humidity control in summer, because it never runs long enough to dry the air
- More wear on the compressor, from constant starts
- Worse efficiency than the smaller unit would have delivered
- A higher bill for the privilege of buying more equipment
A correctly sized heat pump runs longer and gentler. That is what you want.
Want it done properly?
Tell us about the property and what you are heating with now. We will do the calculation and tell you what the work takes.