Is the REHP50 right for your home?
The Rinnai REHP50 is a 50-gallon nominal hybrid electric water heater with 46 gallons of rated storage. It combines a heat pump with resistance elements and carries a 73-gallon first-hour rating. For a replacement, we compare that delivery rating with your busiest period of hot-water use, rather than assigning a fixed number of people to the tank.
The narrower body can be useful when floor space is limited, but this is a tall heater. Before choosing it, WHE checks the access route, overhead space, room airflow and condensate drainage. A conventional 50-gallon electric tank fitting in the space does not establish that the REHP50 will fit.
Verified Rinnai REHP50 specifications
| Nominal capacity / rated storage | 50 gallons / 46 gallons |
|---|---|
| Type / energy source | Hybrid heat pump with electric resistance elements / electric |
| Uniform Energy Factor | 3.75 UEF |
| First-hour rating | 73 gallons |
| Listed recovery at a 90°F rise | 27.5 gallons per hour |
| Power supply / breaker | 208–240V, 60Hz, single phase / 30 amps |
| Electrical ratings | 4,500W element rating; 500W compressor; 5,000W total input; 21.5A maximum current |
| Drawing A: height / B: diameter | 66.4 / 21.7 inches |
| Water connections | ¾-inch MNPT hot and cold side connections |
| Condensate connection | ¾-inch male barb / hose connection in the manual |
| Approximate unit weight in specification sheet | 218 lb |
| Limited warranty | 10 years tank and other parts; 1 year reasonable labor, subject to the applicable warranty terms |
First-hour rating measures delivery under standardized conditions; it is not the amount of water stored. UEF is an efficiency comparison, not a prediction of your bill. Room temperature, inlet water temperature, operating mode and usage affect performance. The listed recovery figure should not be treated as a heat-pump-only recovery rate.
Dimensions, service access and document differences
The REHP50 drawing lists A = 66.4 inches high and B = 21.7 inches in diameter. These are unit dimensions, not a complete installation envelope. Side plumbing, a drain pan, filter removal, anode access and service space must be allowed for separately.
Rinnai’s product-page summary instead gives 66.8125 inches high × 22 inches wide and 212 pounds. This guide uses the labeled A and B dimensions and weight in specification sheet 800000224(03), December 2025, linked from that model page. Because those published figures differ, WHE confirms the exact supplied unit and drawing before a tight-space installation.
Airflow, electrical supply and condensate
This is an indoor electric heater. It draws heat from the air and releases cooler air, so WHE evaluates usable room volume, air movement and operating sound. A garage may work well; a small enclosed closet needs a suitable ventilation or ducting arrangement. Air ducts are not a combustion flue.
Rinnai’s manual shows an unducted arrangement with more than 700 cubic feet of free room volume and separate options for smaller spaces. Its clearance table lists 6 inches on the left and 2 inches on the right, while recommending 12 inches at the sides and 20 inches above for service and performance. These examples must be checked against the complete installation instructions and actual air path.
WHE verifies the 208–240V supply, 30A circuit and equipment nameplate. This is not a 120V plug-in model. The manual describes the heat-pump air-temperature operating range as 3–42°C, approximately 37–108°F; Rinnai’s sheet rounds it to 37–107°F. Avoid choosing a location on the assumption that heat-pump operation is unrestricted in very hot or cold air.
The manual specifies a ¾-inch barbed condensate connection, although the website’s summary labels it MNPT. We inspect the supplied fitting and arrange drainage or a suitable condensate pump. Condensate must not discharge into the water-heater drain pan. Water pressure, thermal expansion, relief-valve discharge and leak protection are also part of the installation review.
Operating modes and optional leak protection
The series offers Economy, Heat Pump, Hybrid, E-Heater and Vacation modes. Resistance heating can help meet demand, but greater element use changes energy consumption. The CTA-2045 port supports compatible demand-response equipment; it should not be mistaken for an included Wi-Fi controller.
Rinnai lists leak kit 103000119 and ducting kit 103000120 as optional accessories. Do not assume that a bare REHP50 includes a leak sensor or automatic water shutoff. WHE confirms the accessories included in the proposed installation.
Vacation Mode requires a mixing valve. Rinnai’s September 2026 Technical Bulletin 217 applies to this model. At the end of a vacation cycle, stored water can reach approximately 140–149°F for the tank-cleaning cycle. Rinnai says not to use Vacation Mode without a correctly installed and working ASSE 1017 thermostatic mixing valve. Have a qualified installer verify the valve and delivery temperature before using this feature.
Compare the REHP50 and REHP80
| Model | Nominal / rated capacity | UEF | First-hour rating | Drawing A × B |
|---|---|---|---|---|
| Rinnai REHP50 | 50 / 46 gal | 3.75 | 73 gal | 66.4 × 21.7 in. |
| Rinnai REHP80 | 80 / 74 gal | 4.00 | 91 gal | 74.2 × 25.6 in. |
The REHP80 adds 28 gallons of rated storage and 18 gallons in the first-hour test. It is also 7.8 inches taller and 3.9 inches wider using the same specification drawing. Both list 27.5 GPH recovery at a 90°F rise, so moving to the 80 increases reserve and tested first-hour delivery without increasing the published recovery figure.
If your existing heater only falls short during back-to-back showers or a large bath, tell us when that happens. The solution may involve more storage, a different operating mode or changes elsewhere in the installation; capacity alone does not identify the cause.
Maintenance and limited warranty
Keep the air filter, condensate route and service panels accessible. Rinnai recommends cleaning the air filter every three months; sediment and anode maintenance also need attention according to water conditions and the manual.
The manufacturer’s limited warranty lists 10 years for the tank and other parts and one year of reasonable labor for covered defects. Qualified installation, proper maintenance, proof of purchase and other conditions apply. It is not blanket coverage for every removal, installation or service expense.
Manufacturer documents and local installation
Review the Documentation section of Rinnai’s official REHP50 product page for specification sheet 800000224(03) and the installation manual. At our October 17, 2026 review, the download labeled 100000867(04) delivered 100000867(05), July 2026. The September 2026 Vacation Mode bulletin above adds guidance that must be considered with the manual.
For Palm Beach Gardens, Jupiter and nearby Palm Beach County homes, WHE compares the existing installation, peak demand and available space before confirming equipment and installation scope. See our Rinnai installation page, hybrid water heater service and water heater model catalog. Share photos of the current heater and label when requesting an estimate.
Rinnai REHP50 FAQs
How much water does the REHP50 actually store?
It is sold in the 50-gallon class and lists 46 gallons of rated storage. Its 73-gallon first-hour rating measures delivery during the test’s first hour, rather than stored capacity.
Can the REHP50 replace my existing electric tank?
Possibly. WHE checks physical fit, the electrical circuit, airflow, drainage and service access before recommending a replacement. A matching gallon label alone does not establish compatibility.
Does this model include automatic leak shutoff?
The manufacturer lists leak kit 103000119 separately. Confirm the accessories included in the actual equipment and installation proposal.
Can I use Vacation Mode when I travel?
Only after a qualified installer verifies a properly installed, functioning ASSE 1017 thermostatic mixing valve. Rinnai’s TB-217 explains that the end-of-cycle cleaning function can raise tank water to approximately 140–149°F.
What warranty does Rinnai list?
The limited warranty provides 10 years for the tank and other parts and one year of reasonable labor for covered defects, subject to its installation, maintenance and eligibility requirements. Review the certificate for the supplied unit.