Efficient Hot Water That Costs Less to Run: Rinnai REHP50 50-Gallon Hybrid Heat Pump Water Heater

The Rinnai REHP50 is a residential hybrid electric water heater that pulls heat from the surrounding air instead of generating it all with resistance elements, which is why it earns a 3.75 Uniform Energy Factor and NEEA Tier 4 rating. It holds 50 gallons nominal (46 gallons rated) and delivers a 73-gallon First-Hour Rating, so it's sized to keep up with a busy household's mornings without the standby losses of an oversized tank. A 4,500W electric element backs up the heat pump for high-demand stretches, and five operating modes let you dial in the balance between efficiency and recovery speed. It's ENERGY STAR certified and CTA-2045 demand-response capable, which opens the door to utility rebates in many areas, and it installs indoors with a duct-ready design for tight mechanical spaces.

Key Features

Heat Pump Efficiency That Cuts Electric Bills

Rather than relying solely on resistance heat, the REHP50 moves warmth from the surrounding air into the tank, which is how it reaches a 3.75 UEF, well above a standard electric water heater. The 500W compressor does most of the work day to day, and the 4,500W element only kicks in when recovery needs to speed up.

Enough Hot Water for a Full Household

A 73-gallon First-Hour Rating and 27.5 GPH recovery at a 90°F rise mean back-to-back showers, laundry, and dishes don't run the tank dry. That capacity comes from a 50-gallon nominal tank, so you're not paying to heat and store more water than the household actually needs.

Five Modes and a Quiet Variable-Speed Fan

Heat Pump, Hybrid, E-Heater, Economy, and Vacation modes let you prioritize maximum efficiency, fastest recovery, or a balanced setting depending on the season or how many people are home. The variable-speed fan keeps operation quiet enough for a laundry room or hallway closet, and it can be ducted with an optional kit if the space needs the airflow managed.

Built for Straightforward Installation

Standard 3/4" MNPT hot, cold, and condensate connections mean it installs much like a conventional electric tank, and it ships with the T&P valve, drain valve, and drainage pipe already accounted for. The heat pump operates down to 37°F ambient, and Rinnai designed the unit for zero clearance along the sides and back, though you'll still want to plan for top access for service.

Product Details

• 50 gallon nominal capacity with 73 gallon First-Hour Rating
• 3.75 Uniform Energy Factor
• NEEA Tier 4 efficiency rating
• 27.5 GPH recovery at a 90°F rise
• Five operating modes including Vacation mode
• Variable-speed fan for quiet operation
• 4,500W electric backup element for high-demand recovery
• Duct-ready design for tight or enclosed spaces
• CTA-2045 demand-response capable for utility programs
• Recirculation capable
• ENERGY STAR certified
• 10-year tank and parts warranty

Rinnai has been innovating home and water heating since 1920, offering high-efficiency tankless water heaters, boilers, and HVAC systems. 

Additional Information

• Brand: Rinnai
• MPN: REHP50
• Series: REHP
• Product Type: Residential electric hybrid heat pump water heater
• Nominal Capacity: 50 gallons
• Rated Capacity: 46 gallons
• Tank Material: Glass-lined steel with anode rod
• Dimensions: Approx. 66.8" H x 22" diameter
• Unit Weight: Approx. 212 lb
• Shipping Weight: Approx. 264.5 lb
• Connections: 3/4" MNPT hot, cold, and condensate
• Electrical: 208/240V, single phase, 30A dedicated circuit

Learn more about the Rinnai REHP Series Residential Hybrid Water Heater in our article, Pros and Cons of Tankless Water Heaters.

Rinnai REHP50 FAQ

Will the REHP50 provide enough hot water for my household?

With a 73-gallon First-Hour Rating and 27.5 GPH recovery at a 90°F rise, the REHP50 is built to handle a full household's morning demand, including back-to-back showers along with laundry or dishwashing. If your household regularly runs several fixtures at once or you have five or more people at home, the larger REHP80 may be worth comparing before you decide.

How much can the Rinnai REHP50 actually save compared to a standard electric water heater?

The REHP50's 3.75 Uniform Energy Factor comes from moving heat out of the surrounding air rather than generating nearly all of it with resistance elements, which is the main reason hybrid heat pump water heaters use significantly less electricity than conventional electric tanks over a year of typical use. Because it's ENERGY STAR certified and NEEA Tier 4 rated, it also tends to qualify for utility rebates that a standard electric tank won't.

Where can I install the REHP50, and does the space need to meet any requirements?

The REHP50 is designed for indoor installation only, and the heat pump needs a reasonable volume of surrounding air to draw heat from, so a small, sealed closet may need the optional ducting kit to bring in enough air and vent exhaust properly. The compressor operates efficiently down to 37°F ambient, and while Rinnai designed the unit for zero clearance along the sides and back, you'll still want to leave room above it for service access.

What's the difference between the REHP50 and the REHP80?

The REHP50 holds 50 gallons nominal with a 73-gallon First-Hour Rating and a 3.75 UEF, while the REHP80 steps up to 80 gallons nominal, an 88-gallon First-Hour Rating, and a slightly higher 4.0 UEF. Both share the same 208/240V, 30A electrical requirements and 10-year warranty, so the choice usually comes down to household size and how much simultaneous hot water demand you need to cover.

What size dedicated circuit does the REHP50 need, and can it share a circuit with anything else?

The REHP50 requires its own dedicated 208/240V, 30A circuit, and it shouldn't be shared with other appliances or outlets. Most homes already running a standard electric water heater will need an electrician to confirm the panel has room for a 30A breaker, since electric heat pump models draw more than a typical resistance-only tank on startup.

If you have questions or need assistance sizing your pump, then the Plumbing Deals team can help! Use the live chat feature, email at contact@plumbingdeals.com, or give us a call at 888-682-5956!

Weight	265.0 lb
Certifications	AHRI, Energy Star, UL
Collection	REHP Series
Connection Size	3/4 in.
Connection Type	Threaded
Height	66.40 in.
Horse Power	1/3
Inlet Size	3/4 in.
Installation Type	Free Standing
Length	21.70 in.
Room	Utility
Vent Type	Atmospheric
Voltage	240 V / 60 Hz
Width	21.70 in.
Inventory Number	RINREHP50
MPN	REHP50
Amps	21.5

• Owner's Manual
• Energy Guide