ThermoMate ES400B Mini Tank Water Heater — 4 Gallon Point-Of-Use, 120V Under Sink

Fast hot water where you need it

Meet the ThermoMate ES400B, a compact four-gallon mini tank designed to bring hot water exactly where you want it. Its small footprint fits neatly under most sinks or inside cabinets, making it a practical choice for kitchens, bathrooms, and other tight spaces. With 24 hours of standby and quality foam insulation, you get hot water with minimal waiting and less wasted water when you turn on the tap.

Engineered for flexible placement, the ES400B can function as a standalone point-of-use heater or act as a booster to a larger hot water system. It features 1/2-inch NPT water connections, a 120V corded power option, and mounting versatility—shelf, wall, or floor—so you can tailor the setup to your space and lifestyle.

What makes it stand out

• On-demand hot water at the sink, helping reduce water waste and speeding up everyday tasks.
• A compact footprint (12.6"W x 12.4"D x 24.3"H) that fits in tight cabinets or under-sink areas.
• Glass-lined enamel coating and a UL-listed safety valve support long, reliable use in a home setting.
• Adjustable temperature range from 68°F to 140°F for comfortable, user-friendly control.

Key installation and operation details

• 1/2-inch NPT inlet and outlet connections for straightforward plumbing.
• 120V power via a standard outlet; corded design offers flexible placement options.
• Mount it on the wall or floor, or use inline as a booster to a larger system.

In daily use, the ES400B supports a variety of tasks—from rinsing dishes and filling pots to quick hand washing or baby bottle needs—by delivering hot water close to the source. The insulated tank minimizes heat loss between uses, while the durable interior helps resist corrosion over time.

Durability, safety, and care

The combination of a gold porcelain enamel interior and a USA-made safety valve emphasizes durability and safety in regular home use. With simple maintenance, you can keep steady performance in compact living spaces for years to come.

Designed for spaces where every inch counts, the ThermoMate ES400B offers a practical, adjustable solution for under-sink hot water needs. It presents a clear path to convenient hot water without overpromising outcomes.