AO Smith ProMax SL 100-Gallon Electric Water Heater
AO Smith ProMax SL 100-Gallon Electric Water Heater Review
The AO Smith ProMax SL 100-Gallon Electric is A.O. Smith's largest commonly-available residential electric tank, sized for very large households or commercial-residential crossover applications. The "SL" designation identifies the standard line.
Specs: 100 gallons stored, two 4500W heating elements (240V), UEF 0.90, 116-gallon FHR, 6-year tank and parts warranty. Glass-lined steel tank, magnesium anode rod. About 65" tall × 30" diameter.
The 100-gallon capacity covers 6+ person households or applications with extreme overlapping demand. Beyond 100-gallon, the path is typically gas conversion, tankless conversion, or heat-pump upsize.
For households with basement install supporting heat-pump, the AO Smith Voltex 100-gal heat-pump operating cost is dramatically lower — heat-pump nearly always wins for very-large electric capacity when install location supports.
About $1,300 unit, $2,000 installed. Right buyer: 6+ person primary residence with electric utility only, install location not supporting heat-pump, or commercial-residential crossover application (small restaurant, multi-family residential).
- No combustion, no venting required — installs anywhere with 240V electrical access
- UEF 0.85 electric — well-insulated design minimizes standby loss compared to standard models
- Large 100-gallon reserve — comfortably serves 5+ person households in peak-use periods
- 115-gallon first-hour rating — handles morning-rush simultaneous demand without shortfall
- 6-year warranty — below the 8–12 year average for premium models in this class
- Resistance electric has slower recovery than gas at comparable capacity — schedule heavy use to match tank recovery