What it delivers
The Mount Steel MST-TLS18A 19 kW Electric Tankless Water Heater is a whole-house electric tankless rated at 19 kW on 240 volts.
At a 45°F rise (mild inlet water to a 120°F set point) it holds about 2.9 GPM, 1 shower at 2 GPM; in winter, at a 70°F rise, about 1.9 GPM, less than one 2 GPM shower. Try your own inlet temperature.
At 240 volts 19 kW is about 79 amps. 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: Overheat Protection, Self-Modulating; model: MST-TLS18A.
The listing gives dimensions of 12.2 in (W) x 18.5 in (H).
Warranty, per the listing: 8-year limited manufacturer warranty on the heat exchanger and 3-year limited manufacturer warranty on parts.
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
- 19 kW
- No venting or gas line
Trade-offs
- Draws about 79 A
- Weak at a large winter rise
- 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 | MST-TLS18A | Retailer |
|---|---|---|
| Dimensions (seller) | 12.2"W x 18.5"H | Retailer |
| Features (seller) | Overheat Protection, Self-Modulating | Retailer |
| Voltage | 240 V | Retailer |
| Warranty | 8-year limited manufacturer warranty on the heat exchanger and 3-year limited manufacturer warranty on parts. | Retailer |
| Power | 19 | Retailer |
Rival units at this flow
More electric tankless water heaters rated for similar demand
Final verdict
A solid whole-house electric tankless for one shower at a time in mild climates.
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