Heat Pump Sizing Calculator
Capacity check at the winter design point using the capacity-derate curve.
Cold-climate (EVI) units hold capacity far better (~1%/ยฐC). The 'balance point' where the curves cross sets your backup-heat hours.
Formula
Heat Pump Sizing Calculator is a free heat pump sizing for HVAC designers, technicians and energy auditors โ instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Heat Pump Sizing Calculator
Capacity check at the winter design point using the capacity-derate curve. The calculation implements cap(T) โ rated ร (1 + 0.022ยท(T โ 8.3)) for standard-tech units (AHRI 210/240 ratings; NEEP ccASHP spec). Cold-climate (EVI) units hold capacity far better (~1%/ยฐC). The 'balance point' where the curves cross sets your backup-heat hours.
How to use Heat Pump Sizing Calculator
- 1Enter Heat loss at design temp in kW.
- 2Enter HP rated capacity (at 8.3 ยฐC/47 ยฐF) in kW.
- 3Enter Winter design temperature in ยฐC.
- 4Read Capacity at design temp, Of load covered instantly โ no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Heat Pump Sizing Calculator?
- โImplements the standard formula โ cap(T) โ rated ร (1 + 0.022ยท(T โ 8.3)) for standard-tech units
- โReference cited on-page: AHRI 210/240 ratings; NEEP ccASHP spec
- โOne-click SI โ Imperial toggle โ values convert in place, physics stays in SI
- โBuilt-in engineering verdict flags out-of-range results instantly
- โRuns entirely in your browser โ nothing uploaded, free forever
Frequently asked questions
What formula does the Heat Pump Sizing Calculator use?+
It computes cap(T) โ rated ร (1 + 0.022ยท(T โ 8.3)) for standard-tech units, per AHRI 210/240 ratings; NEEP ccASHP spec. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Cold-climate (EVI) units hold capacity far better (~1%/ยฐC). The 'balance point' where the curves cross sets your backup-heat hours.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Heat Pump Sizing Calculator free to use?+
Yes โ completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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