Choosing the best tankless water heater is all about finding the right balance between performance, efficiency, and cost for your home’s hot water needs. Whether you’re upgrading from a traditional tank or installing one in a new build, a tankless water heater offers endless hot water, energy savings, and space efficiency.
Here are the best tankless water heaters you can buy based on my experience with different models, installations, and real-world performance.
Best Buy Tankless Water Heaters Overview
| Heater Name | Fuel Type | Max GPM | Efficiency (%) | Best For | Price Range |
|---|---|---|---|---|---|
| Rinnai RUR199iN | Natural Gas | 11 GPM | 96% (Condensing) | Whole-house, large homes | $$$$$ |
| EcoSmart ECO 27 | Electric | 6.6 GPM | 99.8% | Medium homes, budget-friendly | $$ |
| Takagi T-H3-DV-N | Natural Gas | 10 GPM | 93% (Condensing) | Whole-house, high-demand homes | $$$$ |
| Rheem RTEX-18 | Electric | 4.4 GPM | 99.8% | Small to medium homes, point-of-use | $$ |
| Stiebel Eltron Tempra 24 Plus | Electric | 5 GPM | 99% | Whole-house, energy-efficient | $$$ |
1. Rinnai RUR199iN – Best Overall Tankless Water Heater
For those seeking the best-in-class performance, the Rinnai RUR199iN is a premium natural gas tankless water heater that offers high flow rates, condensing efficiency, and top-tier features.
Key Features:
- Max GPM: Up to 11 GPM (perfect for large homes with multiple showers running simultaneously).
- Efficiency: 96% thermal efficiency thanks to its condensing technology, meaning it reuses heat from exhaust gases, saving energy.
- Recirculation Pump: Built-in recirculation pump that reduces wait time for hot water by constantly circulating hot water through your pipes.
- Wi-Fi Compatibility: Allows remote control and scheduling via smartphone, perfect for managing energy use.
Best For:
- Large homes with high hot water demand.
- Homes needing a recirculating system for instant hot water at all fixtures.
- People who want top-tier efficiency and smart home compatibility.
Pros:
- High flow rate—supports multiple fixtures and appliances at once.
- Built-in recirculation pump for instant hot water.
- Extremely energy-efficient with a 96% rating.
- Wi-Fi compatible for remote operation.
Cons:
- High upfront cost, but you get premium features.
- Requires professional installation due to gas and venting requirements.
2. EcoSmart ECO 27 – Best Electric for Budget-Conscious Buyers
The EcoSmart ECO 27 is a standout for budget-conscious homeowners who still want a reliable, efficient electric tankless water heater. It’s a great fit for medium-sized homes with moderate hot water demand.
Key Features:
- Max GPM: Up to 6.6 GPM in warmer climates, but performance drops in colder areas.
- Efficiency: 99.8% energy-efficient thanks to its self-modulating technology, which only uses energy when you need it.
- Compact Design: Takes up minimal space and can be wall-mounted almost anywhere.
- Digital Temperature Control: Allows precise adjustment in 1-degree increments.
Best For:
- Medium homes or homes in warmer climates where cold incoming water won’t reduce flow rates drastically.
- Budget-conscious buyers who want a cost-effective yet efficient solution.
Pros:
- Affordable and highly efficient.
- Compact and lightweight—easy to install.
- Digital temperature control offers precise temperature management.
Cons:
- GPM drops significantly in colder climates.
- Limited to electric systems, so may not be ideal for homes with gas availability.
3. Takagi T-H3-DV-N – Best for Large Homes with High Demand
For large homes with high hot water demand, the Takagi T-H3-DV-N is a natural gas powerhouse. Its 10 GPM flow rate and 93% efficiency make it ideal for homes with multiple showers, dishwashers, and washing machines running simultaneously.
Key Features:
- Max GPM: 10 GPM, easily supporting multiple high-demand applications at once.
- Condensing Technology: Delivers 93% efficiency by using the heat from exhaust gases.
- Durability: Built for long-term use with high-quality materials.
- Low NOx Emissions: Complies with emissions regulations, making it an eco-friendly choice.
Best For:
- Large homes with multiple bathrooms and high simultaneous water usage.
- Homeowners who prioritize energy efficiency and long-term durability.
Pros:
- High flow rate supports large households.
- Condensing technology for increased efficiency.
- Long-lasting build quality.
Cons:
- High upfront cost.
- Requires professional installation and venting.
4. Rheem RTEX-18 – Best for Small to Medium Homes
The Rheem RTEX-18 is a solid electric option for small to medium homes or as a point-of-use heater for specific fixtures. It’s simple to install, highly efficient, and delivers consistent hot water for moderate hot water needs.
Key Features:
- Max GPM: Up to 4.4 GPM, ideal for 1-2 bathrooms in warm climates or lower water flow in colder areas.
- Efficiency: 99.8% efficient, saving on electric bills with on-demand heating.
- Compact and Easy Installation: No venting required, so installation is much easier compared to gas units.
- Digital Control: Precise temperature control with LED display.
Best For:
- Small to medium homes with moderate water needs.
- Homes looking for an easy-to-install electric solution.
- Point-of-use installations for kitchens, bathrooms, or laundry rooms.
Pros:
- Affordable and energy-efficient.
- Compact and lightweight—easy to fit in small spaces.
- No venting needed, making it ideal for indoor use.
Cons:
- Lower flow rate means it’s not suitable for large households with high hot water demands.
5. Stiebel Eltron Tempra 24 Plus – Best for Energy Efficiency
The Stiebel Eltron Tempra 24 Plus stands out for its high efficiency and ability to deliver hot water consistently, even in colder climates. Its 99% efficiency rating means you’re getting the most out of every kilowatt of electricity.
Key Features:
- Max GPM: Delivers up to 5 GPM, which can handle multiple low-demand fixtures simultaneously.
- Advanced Flow Control: Automatically adjusts water flow to ensure hot water is always available without sudden temperature changes.
- Sleek, Modern Design: Compact and easy to install in small spaces.
- Energy Efficient: 99% energy efficiency, with self-modulating technology to adjust energy use based on demand.
Best For:
- Energy-conscious homeowners who want to minimize energy consumption while still enjoying consistent hot water.
- Homes in colder climates that require a reliable electric heater for multiple fixtures.
Pros:
- High energy efficiency for long-term savings.
- Advanced flow control prevents cold water bursts.
- Ideal for homes with moderate hot water demand.
Cons:
- More expensive upfront compared to budget models.
- Flow rate may struggle with multiple fixtures in larger homes.
Key Factors to Consider When Choosing a Tankless Water Heater
1. Fuel Type (Electric vs. Gas)
- Electric tankless heaters: Easy to install, energy-efficient, and perfect for homes without gas lines.
- Natural gas/propane heaters: Higher flow rates and better suited for large homes with heavy water demand, but installation is more complex due to venting and gas lines.
2. Flow Rate (GPM)
- GPM (Gallons Per Minute) measures how much hot water the heater can deliver. For small homes, 4-5 GPM is sufficient, while larger homes with multiple bathrooms may need 8-11 GPM.
3. Energy Efficiency
- Look for energy-efficient models (above 90%) to save on long-term operating costs. Condensing models reuse heat from the exhaust, boosting efficiency.
4. Installation Requirements
- Gas units require venting and may need professional installation. Electric models are easier to install but may need an upgraded electrical panel, especially for high-powered units.
5. Climate
- In colder climates, electric tankless heaters may see a drop in performance as the incoming water is colder. Gas models typically handle colder climates better