WattCost

Data through April 2026

Running cost · Water Heaters (Electric) · ENERGY STAR certified

Rinnai REHP50

For a standard household draw pattern, the Rinnai REHP50 uses a certified 844 kWh per year: roughly $159 annually at the national average rate. That puts it in the most efficient tenth of every certified electric water heater — 22% less electricity than the median, ranked 36 of 566. The same unit costs $104 a year in North Dakota but $393 in Hawaii — electricity rates, not the appliance, make the difference.

Estimated annual running cost · U.S. average rate 18.8¢/kWh

$159/yr

$121 · cheapest certified water heaters (electric)$328 · priciest
Per month
$13.24
Per day
44¢
Certified use
844 kWh/yr
Type
Hybrid/Electric Heat Pump
Heat pump type
240 Volt Integrated HPWH
Storage volume
46 gal
First-hour rating
73 gal
UEF
3.75
643 kWh1,741 kWh
Where the Rinnai REHP50 (▮) sits among all 566 certified water heaters (electric), by annual kWh

What it costs in every state

Rinnai REHP50: 844 kWh/yr × each state's average residential rate (EIA)
StateRate ¢/kWhThis model $/yrRelative cost
Alabama17.4¢$147
Alaska27.4¢$231
Arizona15.5¢$131
Arkansas14.2¢$120
California35.3¢$298
Colorado16.5¢$140
Connecticut32.2¢$272
Delaware18.8¢$159
District of Columbia25.4¢$214
Florida15.4¢$130
Georgia15.4¢$130
Hawaiipriciest46.6¢$393
Idaho12.7¢$107
Illinois20.5¢$173
Indiana17.9¢$151
Iowa13.9¢$117
Kansas15.8¢$133
Kentucky15.0¢$127
Louisiana14.4¢$122
Maine28.4¢$240
Maryland22.1¢$186
Massachusetts29.4¢$249
Michigan21.4¢$181
Minnesota16.4¢$138
Mississippi16.8¢$141
Missouri14.0¢$118
Montana13.9¢$117
Nebraska13.3¢$112
Nevada14.3¢$121
New Hampshire27.2¢$230
New Jersey23.5¢$199
New Mexico15.2¢$128
New York29.4¢$249
North Carolina16.3¢$137
North Dakotacheapest12.3¢$104
Ohio19.5¢$164
Oklahoma13.3¢$112
Oregon15.8¢$133
Pennsylvania21.5¢$181
Rhode Island28.3¢$239
South Carolina17.1¢$144
South Dakota14.5¢$123
Tennessee14.9¢$126
Texas17.0¢$143
Utah13.3¢$112
Vermont24.6¢$207
Virginia17.4¢$147
Washington14.4¢$121
West Virginia16.1¢$136
Wisconsin19.2¢$162
Wyoming14.7¢$124

Certified models closest in efficiency

electric water heaters within reach of 844 kWh/yr
ModelkWh/yr$/yr (US avg)
Rinnai REHP50BM844$159
Rinnai REHP50C844$159
Friedrich PROH50 T2 FD400-15846$159
Friedrich PROH50 T2 FD400-30846$159
Friedrich PROH50 T2 FD400-SO846$159
Rheem PROPH50 T2 RH375-15846$159

Run your own numbers

Your rate, your numbers

Per day
44¢
Per month
$13.24
Per year
$159

844 kWh/yr × 18.8¢/kWh = $159/yr

Prefilled with this model's certified 844 kWh/yr — adjust if your usage differs from the DOE test basis. The certified annual kWh comes from the DOE Uniform Energy Factor test, which simulates a typical household's daily hot-water draw pattern. Only electric models (including heat-pump units) are listed — gas models burn gas, not kWh.

Questions, answered with the data

How much electricity does the Rinnai REHP50 use?
ENERGY STAR certifies the Rinnai REHP50 at 844 kWh per year. The certified annual kWh comes from the DOE Uniform Energy Factor test, which simulates a typical household's daily hot-water draw pattern. Only electric models (including heat-pump units) are listed — gas models burn gas, not kWh.
How much does the Rinnai REHP50 cost to run per month?
About $13.24 a month at the U.S. average residential rate (18.8¢/kWh) — 44¢ a day, or $159 a year. Your state's rate moves this up or down; see the table above.
Is the Rinnai REHP50 energy efficient?
It uses 22% less electricity than the median certified electric water heater, placing it in the top 10% of certified models.
What does the Rinnai REHP50 cost to run in the cheapest vs. priciest state?
At current residential rates it costs about $104 a year in North Dakota (12.3¢/kWh) and $393 in Hawaii (46.6¢/kWh).

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