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A Rheem tankless water heater can be electric or gas, and Rheem also makes some of America’s best-selling tanks. Here’s how the lineup fits together.
Rheem is a U.S. water heating and HVAC manufacturer headquartered in Atlanta and part of Japan’s Paloma group. It sells tank, tankless and heat pump water heaters under the Rheem name and sister brands such as Ruud and Richmond.
A Rheem electric tankless water heater (also listed as a Rheem tankless electric water heater) is sized by kW like the table above.
| Model | Power (approx.) | Typical use |
|---|---|---|
| RTEX-04 to RTEX-08 | 4–8 kW | Point-of-use, one sink |
| RTEX-11 to RTEX-13 | 11–13 kW | One shower in warm climates |
| RTEX-18 | 18 kW | Small home, warm climate |
| RTEX-24 / RTEX-27 | 24–27 kW | 1–2 bathrooms, warm to mild climates |
| RTEX-36 | 36 kW | Whole house, warm climates |
Whole-house RTEX models need large dedicated 240V circuits, often 100–150 amps in total. Check the manual for breaker and wire sizes. Compare in electric tankless water heaters.
See condensing vs non-condensing and natural gas tankless water heaters.
Many searches for "Rheem gas water heater" or "Rheem Performance Plus" refer to Rheem’s storage tank heaters, sold in 30–75 gallon sizes in gas and electric. The Classic series is Rheem’s professional-channel tank line. If you’re comparing a Rheem tank with a tankless unit, read tankless vs tank water heaters. Rheem also makes tanks approved for mobile homes.
Popular tank options include the Rheem Performance Plus water heater, the pro-installed Rheem Classic series water heater, and Rheem natural gas water heater and electric water heater Rheem models in common sizes. If you search for a gas water heater Rheem or Rheem gas water heaters, check whether the listing is a tank or tankless unit.
Rheem requires professional installation for full warranty coverage on most products. Flush tankless units yearly. Rheem gas tankless codes such as 11 (no ignition) and 12 (flame failure) are explained in our Rheem error codes guide.
For Rheem tankless water heater install questions, Rheem lists trained contractors on its website.
See electric and gas tankless units with full specs.
Rheem is a major U.S. water heater manufacturer with a wide service network and broad range of electric and gas tankless models. As with any brand, choose the right size and have it professionally installed and maintained.
RTEX is Rheem’s electric tankless series. The number after it, such as 13, 18, 24, 27 or 36, roughly corresponds to the kilowatt rating, which determines how much flow the unit can heat.
These names are mainly used for Rheem’s storage tank water heaters sold at retail, with Performance Plus offering upgraded features and longer warranties. Rheem also uses the Performance name for some tankless models. Check the product type before you buy.
Classic is a line of Rheem tank water heaters typically sold through professional plumbers rather than retail stores.
This guide is general information for U.S. homeowners, not professional advice. Gas, electrical and venting work must follow the manufacturer’s instructions and local codes, and in most areas requires a licensed plumber, electrician or gas fitter and a permit. Specifications and prices change; always confirm details on the product page and in the installation manual.
