Rheem 18kW 240V Tankless Electric Water Heater – Gray | On-Demand Hot Water

Overview

The Rheem 18kW 240V Tankless Electric Water Heater in Gray is designed for mid-range whole-home needs and is well-suited for single shower setups in cooler Midwest climates. Instead of storing hot water, this unit heats on demand, delivering a continuous, endless supply when you need it. The result is reliable hot water without the bulk of a traditional tank, packaged in a sleek, compact footprint.

Part of Rheem’s Performance line, this model blends durable components with modern controls to offer straightforward operation and flexible installation. A digital temperature display keeps settings clear, while self-modulating technology helps match power to your real-time hot water demand. This combination supports a practical, energy-conscious approach to daily hot water use.

Key benefits at a glance

• Endless hot water on demand with quick response to taps or showers.
• Space-saving design about 90 percent smaller than a storage tank, ideal for cramped spaces.
• No venting required, simplifying installation and broadening placement options.

Performance and efficiency

Self-modulating technology adjusts the unit’s power to match hot water demand, which can help reduce energy use compared with traditional storage solutions. The heater supports a flow rate of up to 4.4 GPM, making it suitable for single-use scenarios or light multi-use applications depending on incoming water temperature.

• Flow rate: Up to 4.4 GPM for flexible hot water delivery.
• Durable copper immersion heating elements are field serviceable, supporting longevity and easy maintenance.
• External digital thermostat with an LED display provides clear temperature visibility.
• Bottom 3/4 inch NPT water connections enable straightforward installation or replacement.

Considerations for installation

Capacity will vary with inlet groundwater temperature; colder water can reduce the achievable flow at a set temperature. If groundwater temps are favorable and higher kilowatt options are available, the unit may serve a larger portion of a home. Its compact size and ventless design offer installation flexibility—from a utility closet to a space under a sink.

Why Rheem

Rheem’s Performance line emphasizes on-demand hot water with energy-conscious operation. The combination of a sleek aesthetic, space-saving form factor, and intuitive controls makes it a practical upgrade for homes where space is a premium and venting considerations exist.