What it delivers
The ThermoMate EH180 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.
Expect about 1.8 GPM with cold winter water (a 70°F rise) and 2.7 GPM when the inlet is milder (45°F rise); that is less than one 2 GPM shower in January. Check your house in the planner.
At 240 volts 18 kW is about 75 amps. The maker calls for 2 x separate 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.
Listed details: features: Self-Modulating, advanced water-and-electricity separation structure; connections: 3/4" npt; model: EH180.
The listing gives dimensions of 13.15 in (W) x 17.09 in (H).
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 | EH180 | Retailer |
|---|---|---|
| Dimensions (seller) | 13.15"W x 17.09"H | Retailer |
| Features (seller) | Self-Modulating, advanced water-and-electricity separation structure | Retailer |
| Power | 18 kW | Retailer |
| Voltage | 240 V | Retailer |
| Max flow (maker) | 4.4 GPM | Retailer |
| Breakers (maker) | 2 x separate 40 Amp double-pole breakers | Retailer |
| Connections | 3/4" npt | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
- FOGATTI ET24 Electric Tankless Water Heater
- ThermoMate ET240 24 kW Electric Tankless Water Heater
- WINTEMP WM18V 18 kW Electric Tankless Water Heater
- WINTEMP YQ-WN27K 27 kW Electric Tankless Water Heater
Full electric tankless water heaters spec grid · Every ThermoMate unit in the catalog
Final verdict
A well-specified whole-house electric tankless for one shower at a time in mild climates.
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