DoesTheMath

What size heat pump water heater do I need?

Heat pump water heaters are sized on the same First Hour Rating scale as any storage tank — here is the real FHR spread this registry's own heat-pump models file, by DOE's own household-demand box.


"Heat pump water heater" is not this registry's own record type — it is a model filed as Electric Storage Water Heater whose Uniform Energy Factor clears 2. Sized the same way any storage tank is: First Hour Rating (FHR) must be >= peak hour demand. DOE Energy Saver -- Sizing a New Water Heater (peak hour demand worksheet) publishes gallons per use for six fixtures:

Use Gallons
One shower 20
Shaving 2
Hand dishwashing / food prep 3
Automatic dishwasher 7
Clothes washer (top-loader) 25
Clothes washer (front-loader) 15

What this registry's heat-pump models actually file, by DOE's own box

Household-demand box FHR range (DOE) Heat-pump models on file Real FHR spread
Very small 0–18 gal 0 --
Low 18–51 gal 10 41–46 gal
Medium 51–75 gal 128 51–73 gal
High 75–+ gal 171 75–133 gal

Heat-pump models on file, largest first hour rating first

  • Chiltrix Inc. DHW105 : 133 gal FHR — 1,002 kWh/yr
  • Reclaim Energy MP120F-RC : 121 gal FHR — 1,323 kWh/yr
  • VAUGHN THERMAL MP120F-RC : 121 gal FHR — 1,323 kWh/yr
  • VAUGHN THERMAL MP120FHPT : 115 gal FHR — 1,417 kWh/yr
  • HUBBELL ME120HPT : 105 gal FHR — 1,468 kWh/yr
  • Noritz ME120HPT : 105 gal FHR — 1,468 kWh/yr
  • VAUGHN THERMAL ME120HPT : 105 gal FHR — 1,468 kWh/yr
  • GE Profile PH80S10BNY01 : 101 gal FHR — 1,102 kWh/yr
  • GE Profile PH80S10BPY01 : 101 gal FHR — 1,127 kWh/yr
  • GREE GRS-3.0Pd/TD70GANhA-D : 100 gal FHR — 1,231 kWh/yr
  • Reclaim Energy MP80F-RC : 98 gal FHR — 1,306 kWh/yr
  • VAUGHN THERMAL MP80F-RC : 98 gal FHR — 1,306 kWh/yr

Add up your own household's busiest hour, plus fuel and physical fit, on the water heater selector to narrow this list further.

What it would cost installed in your state

Enter your ZIP to see an installed-cost estimate scaled to your state's cost of living.

Limits

This box comes from a household's peak-hour demand, not from a room's physical space or ambient temperature — a model in the right box here can still fail those separately (see the closet and room-size questions). Estimating your own household's busiest hour is your own job; DOE's worksheet does not do it for you.