Estimate the nominal heat pump capacity needed from a building design load, desired load coverage, sizing allowance, and available unit size. The calculator rounds the target into whole equipment units and identifies nominal installed capacity and any uncovered design load.
Target capacity is a planning value, while nominal installed capacity reflects whole selected units. Final selection must use manufacturer performance at the actual design temperatures and distribution conditions.
Oversizing can increase cost and cycling; undersizing can increase backup-energy use. Final sizing requires a code-compliant load calculation and equipment selection data.
A 30 kW design load at 90% coverage plus a 5% allowance requires 28.35 kW. Using 10 kW units requires 3 whole units.
No. Use a recognized building load calculation and site-specific equipment performance data for final design.
Bivalent systems may intentionally use backup heat during the coldest design conditions.
It adds a selected margin after applying the target load-coverage percentage.
The calculator rounds up because partial equipment units cannot be installed.
No. Verify delivered capacity at the outdoor and supply temperatures used for design.
| Variable | Use |
|---|---|
| Design load | Building demand at design conditions |
| Coverage | Share assigned to heat pumps |
| Allowance | Explicit additional sizing margin |
| Unit size | Delivered capacity basis for unit count |