What it delivers
The Rheem RTEX-24 Electric Tankless Water Heater is a whole-house electric tankless rated at 24 kW on 240 volts. Its listing gives a maximum flow of 5.9 GPM.
Flow depends on how cold the incoming water is. Our estimate from its input: 3.6 GPM at a 45°F rise, falling to 2.3 GPM at 70°F, which is 1 shower at 2 GPM on a cold-climate winter day. Try your own inlet temperature.
At 240 volts 24 kW is about 100 amps. The maker calls for three - 40‑amp double‑pole breakers. A licensed electrician confirms the panel, the service and the wire before it goes in.
No flue, no gas line and a compact box on the wall; the trade-off is that a cold winter inlet cuts its flow sharply.
Also on the listing: features: LED Display; material: Stainless Steel; model: RTEX-24; warranty: Limited lifetime warranty.
The listing gives dimensions of 17.63 in (W) x 18.25 in (H), a weight of 17.8 lb and fittings, aerators in the box.
Warranty, per the listing: Limited lifetime warranty.
Right unit for this house?
Install it when
- One shower at a time in mild climates
- Homes with no gas service
Look at another unit when
- Panels without spare capacity
- More than 1 shower at once in cold winters
Strengths and trade-offs
Strengths
- 24 kW
- Up to 5.9 GPM
- No venting or gas line
- Breakers stated by the maker
Trade-offs
- Draws about 100 A
- Weak at a large winter rise
Install limits
- Figures are the maker's or seller's own. Flow at a rise is our estimate from the input; gas, venting and electrical work needs a licensed professional.
Rated performance
Every figure below comes from the source shown in brackets. Where the maker doesn't state something, we say so instead of estimating.
| Model number | RTEX-24 | Retailer |
|---|---|---|
| Dimensions (seller) | 17.63"W x 18.25"H | Retailer |
| Features (seller) | LED Display | Retailer |
| Power | 24 kW | Retailer |
| Voltage | 240 V | Retailer |
| Max flow (maker) | 5.9 GPM | Retailer |
| Product weight | 17.8 lb | Retailer |
| Warranty | Limited lifetime warranty | Retailer |
| Material | Stainless Steel | Retailer |
| Breakers (maker) | three - 40‑amp double‑pole breakers | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
- Stiebel Eltron Tempra 29 Trend 28.8 kW Electric Tankless Water Heater
- Stiebel Eltron Tempra 36 Trend 36 kW Electric Tankless Water Heater
- Westinghouse ET024CA0G 24 kW Electric Tankless Water Heater
- Stiebel Eltron Tempra 20 Plus 19.2 kW Electric Tankless Water Heater
Full electric tankless water heaters spec grid · Every Rheem unit in the catalog
Final verdict
A practical whole-house electric tankless for one shower at a time in mild climates.
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