What it delivers
The ThermoMate ET180 18 kW Electric Tankless Water Heater is a whole-house electric tankless rated at 18 kW on 240 volts. Its listing gives a maximum flow of 4.4 GPM.
Worked out from its input, it delivers roughly 2.7 GPM when the water only has to rise 45°F, and 1.8 GPM at a 70°F winter rise: 1 shower at 2 GPM in summer, less than one 2 GPM shower in winter. Check your house in the planner.
At 240 volts 18 kW is about 75 amps (the listing states 76 A). The maker calls for 80Amp breaker. The requirement calculator shows it at 208 V too; an electrician confirms the panel.
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.
Other listed details: connections: 3/4" npt; material: Alloy Steel; model: ET180.
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
- 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
- 18 kW
- Up to 4.4 GPM
- No venting or gas line
- Breakers stated by the maker
Trade-offs
- Draws about 75 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 | ET180 | Retailer |
|---|---|---|
| Dimensions (seller) | 13.12"W x 17.12"H | Retailer |
| Features (seller) | Cast Aluminum Heating Chamber, Leaking free and maintenance free heating element | Retailer |
| Power | 18 kW | Retailer |
| Voltage | 240 V | Retailer |
| Max flow (maker) | 4.4 GPM | Retailer |
| Material | Alloy Steel | Retailer |
| Amps (maker) | 76 A | Retailer |
| Breakers (maker) | 80Amp breaker | Retailer |
| Connections | 3/4" npt | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
- APUS AP-ADSK-270G13 27 kW Electric Tankless Water Heater
- WINTEMP WN27 Electric Tankless Water Heater
- ThermoMate EH180 18 kW Electric Tankless Water Heater
- FOGATTI ET24 Electric Tankless Water Heater
Full electric tankless water heaters spec grid · Every ThermoMate unit in the catalog
Final verdict
A sensible whole-house electric tankless for one shower at a time in mild climates.
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