Best Bosch Hot Water Heaters for Homes

So, what are the best Bosch hot water heaters for your residential water heating needs? Let's review the most efficient and high performing tankless and condensing water heaters from the Therm and Greentherm series.

What to look for when searching for the best Bosch tankless water heater

To find out which are the best tankless water heaters from Bosch, we have reviewed most of the single gas units offered by the Bosch manufacturer. We used the following criteria and directions for choosing the best Bosch models:

  • What are the most advanced and useful features offered by the best Bosch tankless water heaters?
  • Do they provide savings on gas, use green technology, and help in reducing the emission of greenhouse gases?
  • Do they offer an innovative design?
  • What are the specifications?
  • Do they provide flexible installation?
  • Are water heaters versatile, offering recirculation and space heating?

Once we select the best Bosch hot water heaters, we will review them in detail, see what they have to offer, benefits, how much money they cost, and show the summary of what other users are saying.

We will also review the Bosch heater's specification for every single gas tankless water heater, do they provide enough hot water for a family of 4 and can they support hot tubs and multiple applications.

Greentherm 9000 series

The Greentherm 9000 series is recommended for homeowners when replacing the traditional hot water tank. It offers top water connections and integrated drain ports, which allows easier installation.

Whether you have a small or large home, there are seven models to choose from, which ensure plenty of hot water for your needs, even for commercial applications.

The 9000 series of tankless water heaters are built as indoor and outdoor models where the indoor include flexible venting for easy and fast installation.

While most models are built to use natural gas, tankless units can be converted to propane utilizing the conversion kit.

The 9900 series comes in three models, having power ranging from 160,000 to 199,000 BTU and capable of reaching up to 8.7 GPM and an energy factor of 0.99. They all utilize a recirculation pump to deliver hot water fast.

The 9800 series consists of four models with the same power as the above 9900 series, but the built-in recirculation pump is unavailable. The Wi-Fi is optional here.

The best one to choose is coming from the premium Greentherm 9900i SE model that utilizes the glass front and integrated Wi-Fi control so it can be controlled using the smartphone (through the app).

Features highlights

  • Seven models available
  • Energy Star approved
  • Energy efficiency up to 0.99
  • Water flow rate from 7-8.7 GPM
  • Top water connections (indoor models)
  • Built-in recirculation pump (some models)
  • The concealed built-in controller on outdoor models of 9800 series
  • Indoor and outdoor installation
  • It can be used with solar energy systems
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Bosch Therm C 1210 ES review

Bosch Therm C1210 ES is the gas condensing tankless water heater, which comes with the highest efficiency and performance of all Therm and Greentherm series models.

The condensing technology makes this Bosch hot water heater unique as it increases its efficiency and lowers the emission of greenhouse gases.


  • ASME certified - complies with the relevant standards and specifications.
  • Ultra-efficient water heating with over 98% efficiency.
  • High water flow rate of 12.1 GPM.
  • Up to 24 units can be linked into one system for high-demanding homes or commercial applications.
  • Flexible direct vent installation; vent pipe can run horizontally or vertically using the vent system with the concentric or two separate pipes.
  • The cheaper vent pipe is used (such as PVC or CPVC), as the water heater releases gases with the lower exhaust temperature. Maximum vent run is up to 63'.
  • Suitable for heating potable water and living space, also recirculation and solar.
  • Great warranty of 15 years.


  • High initial costs and installation.
  • It is not Energy Star ranked (the only model with up to 199,900 BTU are taken into consideration).

Features and specs

  • LCD display with the power bar, temperature, error code, flame, solar mode, and remote control indicators.
  • Program button (to adjust the temperature, fan speed, and more).
  • The diagnostic system with the error codes for easy troubleshooting and fixing. The diagnostic menu also shows the fan speed, temperature, power, water flow, and other important parameters.
  • 225,000 BTU gas input.
  • 12.1 gallons per minute water flow rate.
  • Low minimum water flow needed for activation - 0.5 GP

One is for sure: the best Bosch hot water heater is usually the most expensive, which also uses the latest technology, materials, and the most advanced features.

Based on the experience in water heating, our recommendation is to go with one that meets the demand, provides flexible installation, and offers modulation for steady work and reduced temperature fluctuation... everything else is extra. If you are budget-oriented, buy a Therm 520 HN; if looking for more gadgets, any Energy Star model is good enough.

For those who prefer the top-of-the-line water heater, which utilizes the condensing technology, heats the water with ultra-high efficiency and low heat loss, is green or environmentally friendly, the above Bosch C1210 ES as the best Bosch hot water heater is a perfect choice.

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