Inline water heaters, also known as tankless or on-demand water heaters, are becoming increasingly popular for their energy-saving features and compact design. These systems provide hot water instantly when needed, eliminating the need for a bulky storage tank. Whether you live in a small apartment or want to reduce energy waste in your home, inline water heaters can be a great solution.
In this guide, we’ll explore the best inline water heaters of 2025, highlighting the top models known for their reliability, efficiency, and performance. If you’re looking to upgrade your current water heater or install a new one, our picks will help you choose the right model for your household needs.
Why Choose an Inline (Tankless) Water Heater?
Inline water heaters provide several benefits over traditional tank models. Here’s why you might consider switching to a tankless water heater:
- Instant Hot Water: Inline heaters provide hot water on demand, so you never run out of hot water, even if multiple people are using it simultaneously.
- Energy Efficiency: Tankless water heaters use energy only when hot water is needed, reducing energy consumption and lowering your utility bills.
- Space-Saving Design: These compact systems are designed to be mounted on the wall or in tight spaces, freeing up valuable floor space in your home.
- Longer Lifespan: Inline water heaters typically last longer than traditional tanks, as they have fewer parts that wear out and no tank to corrode.
Top 5 Best Inline Water Heaters of 2025
After reviewing customer feedback, expert recommendations, and energy efficiency ratings, here are the top-rated inline water heaters of 2025:
1. Rinnai V65iN Tankless Water Heater
The Rinnai V65iN is a natural gas-powered inline water heater that delivers high-performance hot water on demand. It’s perfect for medium-sized homes or small apartments, offering reliability, energy savings, and a continuous supply of hot water.
- Capacity: 6.6 gallons per minute (GPM)
- Fuel Type: Natural gas
- Energy Efficiency: High energy factor (EF) for reduced energy consumption
- Warranty: 12-year limited warranty on the heat exchanger
The Rinnai V65iN is compact and efficient, designed for homes with moderate water usage. Its reliable performance and advanced technology make it one of the best gas-powered inline water heaters available.
2. EcoSmart ECO 27 Electric Tankless Water Heater
The EcoSmart ECO 27 is a top-rated electric inline water heater that provides hot water on demand, saving energy while providing reliable performance for larger homes. It’s designed to be highly efficient, offering up to 99.8% energy efficiency.
- Capacity: Ideal for homes with 3-4 bathrooms
- Energy Efficiency: 99.8% energy efficiency with self-modulating technology
- Flow Rate: 6.5 GPM at a 45°F rise
- Warranty: 5-year limited warranty
The EcoSmart ECO 27 is ideal for homeowners who need a high-performance, energy-efficient solution for their entire home. Its advanced technology automatically adjusts energy use based on water demand, ensuring that you never waste energy.
3. Stiebel Eltron Tempra 24 Plus Tankless Water Heater
The Stiebel Eltron Tempra 24 Plus is an advanced electric inline water heater known for its superior temperature control and high energy efficiency. It’s a great choice for homes with moderate hot water demand, offering a steady flow of hot water while keeping energy costs low.
- Capacity: Suitable for homes with 1-2 bathrooms
- Energy Efficiency: 99% energy-efficient with self-modulating technology
- Flow Rate: 4.0 GPM at a 35°F rise
- Warranty: 7-year limited warranty
This model provides reliable performance and is ideal for homes with a few bathrooms or moderate hot water needs. Its compact design and precise digital control make it one of the best electric inline options on the market.
4. Bosch Tronic 3000 4-Gallon Electric Mini-Tank Water Heater
If you’re looking for an inline water heater for point-of-use applications, the Bosch Tronic 3000 mini-tank is a great choice. It’s designed for smaller spaces and provides instant hot water for single applications, such as a bathroom sink or small kitchen.
- Capacity: 4 gallons
- Energy Efficiency: High-efficiency design with minimal standby heat loss
- Installation: Can be installed under sinks or in tight spaces
- Warranty: 6-year limited warranty
The Bosch Tronic 3000 is ideal for homes or apartments that need hot water for a single faucet or small appliance. Its compact size and quick heating capabilities make it a convenient solution for point-of-use applications.
5. Takagi T-KJr2-IN-NG Tankless Water Heater
The Takagi T-KJr2-IN-NG is a natural gas-powered inline water heater designed for medium to large homes. It provides endless hot water while maintaining energy efficiency, making it an excellent choice for households with higher water usage.
- Capacity: 6.6 gallons per minute (GPM)
- Fuel Type: Natural gas
- Energy Efficiency: High energy factor (EF) for reduced energy consumption
- Warranty: 15-year limited warranty on heat exchanger
This tankless water heater offers a compact design, reliable hot water performance, and excellent energy efficiency. It’s perfect for homes with multiple bathrooms or high water usage, providing hot water on demand for all household needs.
How to Choose the Best Inline Water Heater
When selecting the best inline water heater for your home, consider the following factors to ensure you choose the right model for your needs:
1. Household Size and Water Demand
For larger homes with multiple bathrooms, you’ll need a water heater with a higher flow rate (GPM). Smaller homes or apartments may require a unit with a lower GPM or a point-of-use model for single faucets.
2. Energy Efficiency
Look for inline water heaters with high energy factors (EF) or Energy Star ratings. Tankless and hybrid models are generally more energy-efficient than traditional tank water heaters, as they only heat water when needed.
3. Fuel Type
Inline water heaters are available in electric and gas models. Electric models are easier to install but may have higher operating costs. Gas models tend to be more energy-efficient for large homes and offer a faster recovery rate for high water demand.
4. Installation Space
Consider the available space in your home for installation. Tankless water heaters are compact and ideal for small spaces, while gas models typically require venting and may need more room. Choose a model that fits your installation area and energy source availability.
Conclusion
Inline water heaters offer many advantages, including energy savings, space efficiency, and endless hot water on demand. The models we’ve reviewed above are among the best available in 2025, providing excellent performance, reliability, and value.
Ready to upgrade to an inline water heater? Consider one of the top-rated models we’ve highlighted to enjoy consistent, energy-efficient hot water for your home.