Best Combination Tankless Water Heater and Boiler

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Combination tankless water heaters and boilers (also known as combi boilers) are designed to provide both hot water for domestic use and space heating from a single unit. They are ideal for homes where efficiency, space savings, and cost-effectiveness are priorities. Here are the best options for combi units based on performance, efficiency, and reliability:

1. Rinnai M-Series Condensing Combi Boiler

  • Output: 160,000 – 199,000 BTU
  • Efficiency: Up to 95% AFUE (Annual Fuel Utilization Efficiency)
  • Flow Rate: 4.0 GPM
  • Why It’s Great: The Rinnai M-Series is known for its superb energy efficiency and ability to provide both domestic hot water and home heating simultaneously. It features dual stainless-steel heat exchangers, making it incredibly durable and resistant to corrosion. The unit also has built-in recirculation, ensuring hot water is delivered faster to your faucets.
  • Best For: Homes with moderate to high heating demands and 1-2 bathrooms.
  • Key Features:
    • Low NOx emissions, eco-friendly.
    • Compact wall-mounted design saves space.
    • Built-in Wi-Fi capabilities for easy monitoring and control.

2. Navien NCB-240E Combi-Boiler

  • Output: Up to 199,900 BTU
  • Efficiency: 95% AFUE
  • Flow Rate: Up to 4.5 GPM
  • Why It’s Great: The Navien NCB-240E provides high flow rates for domestic hot water while maintaining excellent efficiency for heating. It features dual stainless steel heat exchangers for durability and extended lifespan. The unit also has advanced controls that can adjust water temperature for both heating and domestic use automatically.
  • Best For: Large homes with high hot water and heating demands.
  • Key Features:
    • Compact and space-saving.
    • Energy Star rated, reducing overall energy costs.
    • Compatible with low-temperature heating (radiant floors).

3. Weil-McLain AquaBalance WMB-155C

  • Output: 155,000 BTU
  • Efficiency: 95% AFUE
  • Flow Rate: Up to 3.5 GPM
  • Why It’s Great: Weil-McLain is known for producing reliable, high-quality boilers. The AquaBalance WMB-155C is compact but delivers strong heating and hot water performance. It’s ideal for smaller homes that don’t need the extreme capacity of larger units.
  • Best For: Homes with moderate heating demands and 1-2 bathrooms.
  • Key Features:
    • High-efficiency rating, saving on utility bills.
    • Easy installation and maintenance.
    • Eco-friendly with low NOx emissions.

4. Bosch Greenstar 151 Combi

  • Output: 151,000 BTU
  • Efficiency: 95% AFUE
  • Flow Rate: Up to 3.6 GPM
  • Why It’s Great: The Bosch Greenstar series is known for being highly efficient and quiet. It offers a good balance between cost and performance, making it perfect for small to medium homes. The unit also features modulating technology, which adjusts the boiler’s output based on the demand, saving energy.
  • Best For: Small to medium homes with moderate water needs.
  • Key Features:
    • Compact, wall-mounted design.
    • Quiet operation, making it ideal for residential spaces.
    • Durable and long-lasting components.

5. Noritz CB199-DV-NG

  • Output: 199,000 BTU
  • Efficiency: 95% AFUE
  • Flow Rate: Up to 4.5 GPM
  • Why It’s Great: The Noritz CB199-DV-NG is a great combi boiler for homes that need both space heating and hot water simultaneously. It offers consistent hot water flow rates and modulating gas valves that improve energy savings.
  • Best For: Larger homes with multiple bathrooms and high hot water demand.
  • Key Features:
    • Low NOx emissions.
    • Modulating burners for improved efficiency.
    • Durable heat exchangers.

Key Considerations:

  1. Flow Rate (GPM): Make sure the unit provides enough hot water for your household. For multiple bathrooms, opt for units with at least 3.5 GPM or higher.
  2. BTU Output: The higher the BTU, the more heat the unit can provide. Select a model based on the size of your home and heating needs.
  3. Efficiency (AFUE): Higher efficiency means lower utility costs. Look for units with 90% AFUE or higher.
  4. Installation: Many combi boilers are compact and wall-mounted, saving space. Check if the unit is easy to install or requires professional setup.
  5. Smart Features: Some models come with Wi-Fi compatibility, allowing you to control and monitor the unit remotely.

Conclusion:

For large homes or homes with high water demand, the Navien NCB-240E and Rinnai M-Series are the top picks due to their high flow rates, energy efficiency, and reliability. For smaller homes, the Weil-McLain AquaBalance and Bosch Greenstar 151 offer excellent performance without the need for large capacities.

Choosing the right combi boiler can ensure comfort and energy savings throughout the year, especially when hot water and heating demands are high.

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