Looking for endless hot water, big energy savings, and a sleek upgrade for your home? Whole-house electric tankless water heaters are rapidly replacing bulky tanks, delivering powerful performance, and fitting just about anywhere. Whether you’re tired of cold showers or want to lower your utility bills, this guide reveals the best electric tankless water heaters for whole house use, what to look for, how to choose the right size, and top models for every family.
Quick Picks: Top Electric Tankless Water Heaters for Whole House
-
Best Overall:
EcoSmart ECO 27 Electric Tankless Water Heater – High GPM, smart controls, and proven reliability. -
Best Premium:
Stiebel Eltron Tempra Plus 36 kW Electric Tankless Water Heater – German engineering, digital modulation, and top-tier efficiency. -
Best Budget:
Rheem RTEX-24 Electric Tankless Water Heater – Reliable, easy to install, and powerful enough for small to medium homes.
Buyer’s Guide: Choosing an Electric Tankless Water Heater for Whole House
- Flow Rate (GPM): Calculate how many gallons per minute you need at peak (showers, sinks, dishwasher, laundry running at once). Most families need at least 5–7 GPM for comfort.
- Power (kW): Whole house units start at 18 kW and go up to 36 kW—bigger homes and colder climates need more power.
- Electrical Requirements: These units often require 200-amp service and multiple 40-50 amp breakers. Check your panel before buying.
- Self-Modulation: Smart models automatically adjust energy use to match demand, saving power when possible.
- Temperature Rise: Colder incoming water (Northern states) requires more powerful units to maintain flow and temperature.
- Digital Controls: Look for digital displays and precise temperature adjustment for comfort and safety.
- Warranty: Choose models with strong warranties—at least 5 years on the heat exchanger and parts.
- Brand Reputation: Stick with trusted brands that offer real support, replacement parts, and clear manuals.
How to Size Your Electric Tankless Water Heater
- Count your peak usage: Example – 2 showers (2.5 GPM each), 1 sink (1 GPM), and 1 appliance (1 GPM) = 7 GPM total needed.
- Check the temperature rise needed: Subtract your incoming water temp from your desired output (typically 120°F).
- Compare models: Choose a heater rated for your peak GPM at your needed temperature rise.
- Consult the manufacturer’s sizing chart for accuracy—don’t guess!
Detailed Reviews: Best Electric Tankless Water Heaters for Whole House
EcoSmart ECO 27 Electric Tankless Water Heater
- 27 kW, 240V; handles up to 6.5 GPM (Southern US) or 3.5 GPM (cold climates)
- Self-modulating technology saves energy by adjusting to usage
- Digital display for precise temperature control
- Lifetime warranty for residential use
- Compact design—mounts on the wall, frees up floor space
Pros:
- Top-selling whole-house model
- Proven reliability and easy to service
- Excellent support and warranty
Cons:
- Requires 3 x 40 amp breakers and heavy wiring
- Peak flow drops in very cold climates
Final Verdict: The best value and performance for most homes needing endless hot water.
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Stiebel Eltron Tempra Plus 36 kW Electric Tankless Water Heater
- 36 kW, 240V; delivers up to 7.5 GPM—handles the largest homes and families
- Advanced flow control keeps output steady, even with multiple taps running
- Silent operation and sleek German design
- Digital controls with memory settings for easy use
- Solid 7-year warranty on leaks, 3 years on parts
Pros:
- Unmatched reliability and performance
- Whisper-quiet operation
- Great for cold climates and busy households
Cons:
- Requires four 40A breakers and robust wiring
- Premium price
Final Verdict: The top choice for large homes or those wanting maximum performance and luxury.
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Rheem RTEX-24 Electric Tankless Water Heater
- 24 kW, 240V; up to 5.9 GPM (warm climates), 2.8–3.5 GPM (cold climates)
- External digital thermostatic control with LED display
- Robust copper immersion heating elements—easy to service
- Simple installation with 3/4-inch NPT connections
- 5-year warranty on heat exchanger
Pros:
- Reliable, affordable, and brand-backed
- Great for small-to-medium homes
- Easy-to-read controls
Cons:
- Lower flow in cold climates
- Requires three 40A breakers
Final Verdict: The best budget choice for whole-house hot water in mild to moderate climates.
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Comparison Table: Best Electric Tankless Water Heaters for Whole House
| Model | Power (kW) | Max GPM | Digital Controls | Warranty | Best For | Price Link |
|---|---|---|---|---|---|---|
| EcoSmart ECO 27 | 27 | 6.5 (warm) | Yes | Lifetime | Medium homes | View |
| Stiebel Eltron Tempra Plus 36 | 36 | 7.5 (warm) | Yes | 7 yr leaks | Large homes | View |
| Rheem RTEX-24 | 24 | 5.9 (warm) | Yes | 5 yr | Budget/small homes | View |
FAQ: Electric Tankless Water Heaters for Whole House
- Will an electric tankless water heater work for my whole house?
Yes, as long as you choose the right size and have the required electrical service. Larger homes or those in cold climates may need the highest power models. - How much will installation cost?
Professional installation may cost $800–$2,000, especially if your electrical panel needs upgrades. - Are they energy efficient?
Yes, electric tankless heaters only use power when hot water is running—no standby losses like a tank. - Do I need to upgrade my breaker panel?
Most whole-house models require 200-amp service and several 40–50A breakers. Always consult an electrician before buying. - What maintenance is needed?
Flush the unit annually (especially in hard water areas) to prevent scale buildup and keep it running efficiently.
Conclusion
Upgrading to a whole-house electric tankless water heater means unlimited hot water, a cleaner look, and lower bills. With the right model, you can enjoy modern comfort and reliable performance for years. Choose from our top picks, make sure your home’s electrical system is ready, and experience the freedom of endless hot showers in any season!