Answering your search for reliable, high-flow electric tankless water heaters, these models are designed to deliver up to about 10 GPM for whole-house use. The top picks include self-modulating systems, energy-saving features, and install notes that help you pick the right unit for a multi-bath home or high-demand scenarios. This guide highlights who each product is best for, why it was chosen, and practical cautions to consider before buying.
| Product | Best For | Key Benefit |
|---|---|---|
| WINTEMP 36kW Tankless Electric Water Heater | Homes with 3–5 bathrooms in mild climates | High output with stable temp and significant energy savings |
| Rheem 18kW 240V Tankless Electric Water Heater | Smaller homes or hot-water adds-on | Compact, adjustable to demand |
| Rheem RTEX-24 24kW 240V Tankless Electric | Mid‑range flow needs in larger homes | Strong performance with flexible temperature control |
| WINTEMP WM27V Plus 27kW Tankless Electric | 2–4 point-of-use needs within home | Smart control and energy efficiency |
| APUS 190,000 BTU Outdoor (Gas) Tankless | Homes with gas-ready systems or outdoor installation flexibility | High BTU and instant hot water on demand |
WINTEMP 36kW Tankless Electric Water Heater
Features include a 36 kW rating at 240V with a maximum current draw of 150A, requiring four 40A double-pole breakers and 8 AWG wires with ground. Water connections are 3/4″ NPT. It uses self-modulating technology to conserve energy and maintain stable hot water output at up to 8.7 GPM. Best for homes with 3–5 bathrooms in mild to moderate climates and where a resident electrician can ensure proper installation. Caution: requires substantial electrical service and professional installation to meet safety standards.
Rheem 18kW 240V Tankless Electric Water Heater
This model features an external digital thermostatic control with an LED display and self-modulation to meet hot water demand. It uses durable copper immersion elements and is field serviceable. Typical flow is up to 4.4 GPM, making it suitable for modest-family homes or adding a point of use. Best for: homes needing reliable, adjustable output in a compact unit. Caution: flow may drop significantly with outdoor cold water temperatures, impacting temperature rise in winter.
Rheem RTEX-24 24kW 240V Electric Tankless
Electrical requirements include three 40A double-pole breakers and a 200A service recommendation. It delivers about 24kW at 240V with a max temperature control range roughly between 80–140°F. Pros: strong performance suitable for whole-home use, especially where multiple showers may operate simultaneously. Limitation: installation demands ample panel space and precise wiring; ensure your home can accommodate the power draw.
WINTEMP WM27V Plus 27kW Tankless Electric
Rated at 27kW (240V) with a maximum current of 113A, this unit requires three 40A breakers and 8 AWG wiring. It provides up to 6.5 GPM of stable hot water output, using smart self-modulating technology and true zero-energy standby when not in use. Best for: mid-sized homes needing efficient hot water with a thoughtful balance of power and install practicality. Caution: ensure your electrical panel can support 113A continuous draw.
APUS 190,000 BTU Outdoor Tankless Water Heater
Note: This is a propane outdoor unit delivering about 8.1 GPM and 190,000 BTU. It is suitable for whole-house use where outdoor installation is preferred and gas connections exist. Best for: homes seeking a gas-powered alternative with high flow, especially when electric service is limited. Caution: not electric; installation requires gas line and venting considerations, plus outdoor-rated clearances.
Buying Guide: Key Purchase Considerations
- Electric capacity matters: Check your main service panel. Units like the 36kW WINTEMP model demand substantial amperage and may require service upgrades.
- Flow vs. temperature: Higher GPM requires greater power. If your climate or water inlet temperature is low, you may experience reduced GPM even among high-output models.
- Electrical wiring and breakers: Most high-output models need multiple double-pole breakers and heavy gauge wiring. Professional installation is usually required.
- Temperature control: Look for models with digital thermostats and self-modulating technology to optimize energy use and stabilize water temperature.
- Installation location: Indoor vs. outdoor, electrical access, and space considerations influence model choice and mounting.
- Safety and compliance: Ensure ETL/UL certifications and local code compatibility. Some units require professional electrical or gas permits.
FAQ
- What is the typical GPM for a 36kW electric tankless heater? – Up to about 8.7 GPM under optimal conditions with mild incoming water temperatures.
- Do I need a dedicated circuit for these heaters? – Yes. High-output units commonly require multiple dedicated double-pole breakers and heavy gauge wiring.
- Can these units replace a traditional tank? – They can provide continuous hot water but may require reconfiguration of plumbing and electrical systems.
- Is self-modulating technology important? – Yes. It improves energy efficiency by matching power usage to demand and water flow.
- What should I consider before choosing gas vs. electric? – Electric units avoid venting and gas line requirements, but you need adequate electrical capacity. Gas units offer different flow dynamics and may be preferred in areas with high natural gas availability.
- Can installation be DIY? – Professional installation is strongly recommended for electrical and gas units due to safety and code compliance.