Ultimate Guide to Tankless Water Heaters: Choosing the Best for Your Home (2025)
Tankless water heaters have transformed the way we think about hot water in our homes. Unlike traditional water heaters that store hot water in a tank, tankless units heat water on demand, providing a continuous supply without the bulk of a tank. This efficiency can lead to lower utility bills and a reduced carbon footprint. In this guide, we will explore the best tankless water heaters available in 2025, their features, benefits, and how to choose the right one for your needs.
| Type | Fuel Source | Flow Rate (GPM) | Ideal Applications |
|---|---|---|---|
| Electric Tankless | Electric | 1.5 – 7.0 | Apartments, small homes, low demand |
| Gas Tankless | Natural Gas/Propane | 3.0 – 10.0 | Large homes, high demand, multiple fixtures |
| Point-of-Use Tankless | Electric | 1.0 – 3.0 | Sinks, small appliances, remote locations |
| Whole House Tankless | Gas/Electric | 5.0 – 10.0 | Entire home, high demand scenarios |
Understanding Tankless Water Heaters
Tankless water heaters, often referred to as “on-demand” water heaters, heat water directly without the need for storage. This means they only operate when hot water is needed, which can significantly reduce energy waste.
Benefits of Tankless Water Heaters
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Energy Efficiency: Since they heat water only when needed, tankless heaters can be 24% to 34% more energy-efficient than traditional storage tank water heaters. This efficiency translates into cost savings on your energy bills.
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Space Saving: Tankless units are compact and can be installed in smaller spaces, making them ideal for apartments or homes with limited area.
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Longevity: Typically, tankless water heaters have a longer lifespan than traditional units—up to 20 years with proper maintenance.
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Continuous Hot Water Supply: Unlike tank heaters that run out of hot water, tankless systems provide a continuous supply, ensuring you won’t run out mid-shower.
Types of Tankless Water Heaters
Tankless water heaters come in various types based on fuel sources and applications. Understanding these types will help you make an informed decision.
Electric Tankless Water Heaters
Electric models are ideal for smaller households or where gas connections are unavailable. They are generally easier to install and require less maintenance compared to gas units.
Gas Tankless Water Heaters
Gas models are more powerful and can handle larger demands, making them suitable for larger homes. They often have higher flow rates but require proper venting.
Point-of-Use Tankless Water Heaters
These are smaller units installed directly at the point of use, such as sinks or small appliances. They provide hot water instantly without the wait.
Whole House Tankless Water Heaters
Designed to supply hot water to the entire home, these units are larger and more powerful, capable of servicing multiple fixtures simultaneously.
Key Features to Consider
When selecting a tankless water heater, several key features should be considered:
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Flow Rate: Measured in gallons per minute (GPM), this determines how much hot water the unit can provide at once. It’s crucial to match the flow rate with your household’s needs.
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Energy Source: Choose between gas or electric based on availability, cost, and energy efficiency.
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Size: Consider the physical dimensions and installation space of the unit.
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Temperature Rise: This refers to the difference between the incoming water temperature and the desired output temperature. Higher temperature rises may require more powerful units.
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Cost: Initial purchase costs can range significantly based on the brand, model, and features. Factor in installation costs as well.
Top Tankless Water Heaters of 2025
After extensive research and analysis of the current market, here are some of the best tankless water heaters for 2025.
Stiebel Eltron Electric Tankless Water Heater
This model is highly rated for its high flow rate and self-modulating technology, which adjusts energy use based on demand, making it energy-efficient.
Rinnai RU199iN Tankless Water Heater
Recognized for its versatility and efficiency, the Rinnai RU199iN is a favorite among professional installers, making it our top pick for overall performance.
Bosch Therm Technology Greentherm
This unit offers a compact design and high energy efficiency, suitable for small to medium-sized homes.
EcoSmart ECO 27 Electric Tankless Water Heater
A budget-friendly option, the EcoSmart ECO 27 is known for its ability to provide hot water for up to three simultaneous showers.
Takagi T-H3-DV-N Tankless Water Heater
This gas model is designed for high-demand situations and is known for its reliability and performance.
Rheem Performance Tankless Water Heater
Offering a good balance of price and performance, this unit is suitable for medium-sized homes.
| Model | Type | Flow Rate (GPM) | Energy Source | Price Range |
|---|---|---|---|---|
| Stiebel Eltron Electric | Electric | 4.0 | Electric | $400 – $600 |
| Rinnai RU199iN | Gas | 7.5 | Natural Gas | $900 – $1100 |
| Bosch Greentherm | Gas | 6.6 | Natural Gas | $700 – $1000 |
| EcoSmart ECO 27 | Electric | 3.5 | Electric | $300 – $500 |
| Takagi T-H3-DV-N | Gas | 10.0 | Natural Gas | $800 – $1200 |
| Rheem Performance | Gas/Electric | 6.0 | Gas/Electric | $600 – $900 |
Installation Considerations
Installing a tankless water heater can be more complex than traditional units. Here are some considerations:
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Location: Ensure the installation area has sufficient ventilation for gas units and is close to the water source.
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Professional Installation: Hiring a certified plumber can ensure correct installation and compliance with local codes.
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Upgrades: Older homes may require plumbing or electrical upgrades to accommodate new tankless units.
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Maintenance: Regular maintenance, including descaling and flushing the system, is essential to keep your unit running efficiently.
Conclusion
Choosing the right tankless water heater can significantly impact your home’s energy efficiency and comfort. With numerous options available, it’s essential to consider factors such as flow rate, energy source, size, and installation requirements. The models highlighted in this guide represent some of the best options in 2025, ensuring you’ll find a unit that meets your household’s hot water demands.
FAQ
What is a tankless water heater?
A tankless water heater heats water on demand, providing a continuous supply of hot water without the need for a storage tank.
How does a tankless water heater work?
When you turn on a hot water tap, cold water travels through a pipe into the unit, where either a gas burner or an electric element heats the water.
What are the main advantages of using a tankless water heater?
They are energy-efficient, save space, provide unlimited hot water, and generally have a longer lifespan compared to traditional water heaters.
How do I choose the right size tankless water heater?
Consider your household’s peak hot water usage, the number of fixtures, and required flow rate to determine the right size.
Are tankless water heaters worth the investment?
While they typically have a higher upfront cost, their energy efficiency and longevity can lead to savings over time.
Can I install a tankless water heater myself?
It’s recommended to hire a professional for installation to ensure safety and compliance with local codes.
How often should I maintain my tankless water heater?
Regular maintenance, including descaling, should be performed at least once a year to ensure optimal performance.
What factors affect the performance of a tankless water heater?
Water temperature, flow rate, and the unit’s heating capacity all affect performance.
Do tankless water heaters work during power outages?
Gas tankless units can work without electricity, but electric models will not function during power outages.
What is the average lifespan of a tankless water heater?
With proper maintenance, tankless water heaters can last between 15 to 20 years.