Heat pumps for Washington
Across the 605 ZIP-code areas in Washington, the winter design temperature runs from 11°F to 30°F for most areas, with a median of 25°F.
The design temperature is the annual 99% value: only the coldest 88 hours of an average year fall below it. Each area takes it from the nearest weather station, 2015 to 2024.
Winter design temperatures across Washington
| Design temperature | Areas | Share |
|---|---|---|
| Below 5°FNo certified heating figure | 1 | 0.2% |
| 5 to 17°F | 207 | 34.2% |
| 17 to 47°F | 397 | 65.6% |
| 47°F and above | 0 | 0% |
| Place | ZIP code | Design temperature |
|---|---|---|
| Okanogan County | 98833 | −3°F |
| Adams County | 99105 | 8°F |
| Cheney | 99004 | 8°F |
| Place | ZIP code | Design temperature |
|---|---|---|
| Sequim | 98382 | 32°F |
| Aberdeen | 98520 | 31°F |
| Artondale | 98335 | 31°F |
Sizes certified to cover a typical house at 25°F
The size calculator uses 16 to 26 Btu/h per square foot for a typical house where the design temperature is 20°F or warmer. Sizes are compared on the 5°F full-speed test.
For each type: the smallest size class whose median model is certified to deliver the bottom of the range at 5°F, and the smallest that reaches the top. The medians count one value per model. Size classes are named by cooling capacity.
1,500 sq ft: 24,0007.03 to 39,000 Btu/h11.43 kW
- 36,000 Btu central models26,400 Btu/h7.74 kW at 5°F, the median of 451 models · covers the bottom of the range
- 54,000 Btu central models40,000 Btu/h11.72 kW at 5°F, the median of 343 models · covers the top of the range
- 30,000 Btu mini-split models25,000 Btu/h7.33 kW at 5°F, the median of 405 models · covers the bottom of the range
- 48,000 Btu mini-split models42,000 Btu/h12.31 kW at 5°F, the median of 321 models · covers the top of the range
2,500 sq ft: 40,00011.72 to 65,000 Btu/h19.05 kW
- 54,000 Btu central models40,000 Btu/h11.72 kW at 5°F, the median of 343 models · covers the bottom of the range
- No central size class reaches 65,000 Btu/h19.05 kW at 5°FThe top of this range takes more than one unit
- 48,000 Btu mini-split models42,000 Btu/h12.31 kW at 5°F, the median of 321 models · covers the bottom of the range
- No mini-split size class reaches 65,000 Btu/h19.05 kW at 5°FThe top of this range takes more than one unit
Your own house
6,618 of 8,420 certified units carry EPA's cold-climate designation. Cold-climate heat pumps by size
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