What it delivers
The Rheem RTEX-36 Electric Tankless Water Heater is a whole-house electric tankless rated at 36 kW on 240 volts. Its listing gives a maximum flow of 6.0 GPM.
At a 45°F rise (mild inlet water to a 120°F set point) it holds about 5.5 GPM, 2 showers at 2 GPM; in winter, at a 70°F rise, about 3.5 GPM, 1 shower at 2 GPM. Try your own inlet temperature.
At 240 volts 36 kW is about 150 amps. A licensed electrician confirms the panel, the service and the wire before it goes in. On its own it takes more than 60% of a 200-amp service.
It skips venting entirely, but the amps are the hurdle: check the panel before the plumbing.
From the listing: connections: 3/4 in. Npt; material: Brass, Copper; model: RTEX-36.
The listing gives a weight of 11.07 kg.
Right unit for this house?
Install it when
- 2 showers at once 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
- 36 kW
- Up to 6.0 GPM
- No venting or gas line
Trade-offs
- Draws about 150 A
- Winter flow is much lower
- Breaker needs not stated
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-36 | Retailer |
|---|---|---|
| Features (seller) | Energy efficient, digital temperature control, compact and stylish design | Retailer |
| Power | 36 kW | Retailer |
| Voltage | 240 V | Retailer |
| Max flow (maker) | 6 GPM | Retailer |
| Product weight | 11.07 kg | Retailer |
| Material | Brass, Copper | Retailer |
| Connections | 3/4 in. Npt | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
- ECOAPTUNIT XY-D08 18 kW Electric Tankless Water Heater
- AIRTHEREAL EVT-27K 27 kW Electric Tankless Water Heater
- APUS AP-ADSK-180G13 18 kW Electric Tankless Water Heater
- SIVUATEK V7B-180B 18 kW Electric Tankless Water Heater
Full electric tankless water heaters spec grid · Every Rheem unit in the catalog
Final verdict
A solid whole-house electric tankless for 2 showers at once in mild climates.
Buy this unit
Our links open this exact model's product page. Prices and stock change; check what's included before you order.
Each button opens this exact model. We may earn a commission on tracked links; it never changes what we publish. Disclosure