Rheem RTEX-27 Electric Tankless Water Heater
- 27000 watts at 240 volts
- 3 heating chambers, copper immersion elements
- 3/4 inch NPT water connections on the bottom
- Digital thermostat, LED display, 1 degree accuracy listed
- Wall mount, 17.8 lb, 3.50 inch depth
- Self-modulating power to match hot water demand
- Field serviceable elements, threaded for replacement
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
An electric tankless heater for single or multiple outlets in homes that can supply its high electrical draw. The listing gives no usable flow figure at a set temperature rise, so size it with Rheem's charts first.
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ASIN: B01N5R9FQBModel: RTEX-27Category: Water Heaters
Overview
Not a storage tank heater, this Rheem unit heats water as it flows through copper immersion elements in separate chambers. An external digital thermostat with an LED display sets the outlet temperature, and the unit adjusts its power to match how much hot water is being drawn.
Continuous hot water without a tank is the attraction, and the copper elements are threaded so a worn one can be replaced in the field. Breaker size, wire gauge and flow at a given temperature rise are missing from the listing, and those decide whether the unit can work in a given house.
Who it's for
Households tired of running a storage tank dry, with an electrician ready to confirm the panel, are the target. Homes with a small panel or no room for new heavy circuits should look at gas or a smaller point of use heater.
Pros and cons
- No storage tank to run out
- Threaded elements replace in the field
- Digital thermostat with LED readout
- Power modulates with hot water demand
- Large electrical draw at full output
- Circuit and breaker requirements not listed
- No flow rating at a set temperature rise
Performance notes
Outlet temperature depends on incoming water temperature and flow, because the elements can only add a fixed amount of heat. Self-modulation lowers power when demand is light, and the thermostat holds the set point while flow stays within what the elements can heat. Colder inlet water leaves less headroom for several fixtures at once.
Specifications
| Brand | Rheem |
|---|---|
| Model | RTEX-27 |
Frequently asked questions
Is the Rheem RTEX-27 a gas or tank water heater?
Neither. It is an electric tankless unit running on 240 volts with no storage tank.
Can a heating element on the Rheem RTEX-27 be replaced?
Yes. Rheem describes the copper immersion elements as field serviceable and threaded for easy replacement.