What it delivers
The ThermoMate ET270 27 kW Electric Tankless Water Heater is a whole-house electric tankless rated at 27 kW on 240 volts. Its listing gives a maximum flow of 5.3 GPM.
At a 45°F rise (mild inlet water to a 120°F set point) it holds about 4.1 GPM, 2 showers at 2 GPM; in winter, at a 70°F rise, about 2.6 GPM, 1 shower at 2 GPM. Check your house in the planner.
At 240 volts 27 kW is about 112 amps (the listing states 114 A). The maker calls for 3 dedicated Double-pole 40AMP Circuit 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.
From the listing: features: Instant hot water, Leaking free & Maintenance free heating element; connections: 3/4" npt; model: ET270.
The listing gives dimensions of 13.12 in (W) x 17.12 in (H) and mount kit in the box.
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
- 27 kW
- Up to 5.3 GPM
- No venting or gas line
- Breakers stated by the maker
Trade-offs
- Draws about 112 A
- Flow drops with cold inlet water
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 | ET270 | Retailer |
|---|---|---|
| Dimensions (seller) | 13.12"W x 17.12"H | Retailer |
| Features (seller) | Instant hot water, Leaking free & Maintenance free heating element | Retailer |
| Power | 27 kW | Retailer |
| Voltage | 240 V | Retailer |
| Max flow (maker) | 5.27 GPM | Retailer |
| Amps (maker) | 114 A | Retailer |
| Breakers (maker) | 3 dedicated Double-pole 40AMP Circuit Breakers | Retailer |
| Connections | 3/4" npt | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
- Rheem RTEX-18 Electric Tankless Water Heater
- Stiebel Eltron Tempra 20 Trend 19.2 kW Electric Tankless Water Heater
- Stiebel Eltron Tempra 24 Trend 24 kW Electric Tankless Water Heater
- WINTEMP WM27V 27 kW Electric Tankless Water Heater
Full electric tankless water heaters spec grid · Every ThermoMate unit in the catalog
Final verdict
A solid whole-house electric tankless for 2 showers at once in mild climates.
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