Bosch Greentherm C 950 ES
Tankless Water Heater
Review and Buying Tips

Explore tankless and condensing water heaters - Bosch Greentherm C 950 ES, built for small and large homes, single or multiple baths, and heating hot water for residential and commercial applications.

With the maximum water flow of 9.4 gallons, and the ability to connect more units into one system, C 950 ES can be used in any region, no matter the climate - warmer or cold, and no matter if it utilizes propane or natural gas. Check out the benefits, features, and main specs.


Models overview

Bosch Greentherm C 950 ES water heaters are designed with tankless and condensing technology so they can provide hot water non-stop, no matter how long you will use it, and without worrying that hot water will run out, as it happens with the tank-type. The heaters are built with no water storage tank, and water is heated while moving through the heat exchanger, resulting in on-demand heating and a continuous supply of hot water.

The Greentherm C 950 ES model is also condensing, which means that the heat from exhaust gases is used for preheating the incoming water, therefore increasing the unit’s thermal efficiency and lowering the temperature of the flue gases at the same time. This will result in more savings during the heating, flexible and cost-effective solution for venting.

Bosch tankless water heaters can provide long-lasting service and the expected lifetime is over 20 years, while the warranty on the heat exchanger is 15 years. What makes them different from the tank-type model is that every component in tankless can be replaced, so less waste goes into landfills.


Condensing and tankless

Bosch Greentherm C 950 ES water heaters (sold on are designed with two heat exchangers; primary for heating water and secondary for preheating, first made of copper and the second one made of stainless steel.

Such a setup results in delivering an endless supply of hot water, with a high energy factor of 0.95, making it Energy Star compliant. This is what allows the C 950 ES model better energy savings, reduced waste and pollution.

The advanced design makes the flame pattern more stable, providing better flame distribution, while the built-in turbulators reduce the scale build-up, and with the reduced thermal stress and number of hot spots, the units can last longer and perform better.

High water flow

Bosch Greentherm C 950 ES is not the largest model from this manufacturer while it still provides much hot water, ranging from low 0.5 to high 9.4 gallons when operating as a single unit. If you need more hot water, get the C 1210 ES model as it can provide up to 12.1 GPM. Thanks to the modulating water valve, users will enjoy improved comfort and better temperature control. The water flow of 9.4 GPM makes these models ideal for homes with up to 4 baths. It is also suitable for the combined heating of space and potable water.

If the demand for hot water is high and more power is needed, Bosch allows connecting up to 24 units using the Intelligent Cascading system and the controller to manage and set the temperature up to 140 F or 184 F depending on the application.

Improved comfort

Almost all water heaters from Bosch, including C 950 ES, use advanced electronics and a built-in control panel to provide enhanced control, convenient monitoring, precise temperature settings, and fewer temperature fluctuations, known as the “cold water sandwich” effect. So, with innovative technology, users will enjoy improved comfort.

Flexible installation

The C 950 ES model has a small, lightweight, and compact construction, offering straightforward wall mounting and flexible installation options, either indoor or outdoor. Due to the condensing technology, indoor models, as the direct vent, can utilize PVC, PP, ABS, and CPVC vents with the horizontal or vertical setup, running through the sidewall or roof. They can use a twin-pipe configuration with the maximum pipe lengths of 63 feet or a concentric system with a pipe length of up to 43 feet.

The unit can also work with the electric mini-tank for recirculation and solar thermal storage tank.

Power adjustment

The heaters are equipped with high-efficiency Ceramat gas burners with low NOx gas emission and the modulating gas valve with a constant gas/air ratio. Thanks to these features, units can provide the maximum gas input of 175,000 BTU and down to 19,900 BTU when a small hot water supply is needed.

Safety features

  • Built-in freeze protection inside the heater, down to 5 F but only for the short-term conditions
  • ECO protection against overheating
  • Flame failure device (ionization flame rod sensor)
  • Outlet temperature sensor
  • Backflow temperature sensor
  • Flue temperature sensor
  • Water drop protection
  • Condensate drain

Related: High-end model - Rinnai RUR98


  • Power: 19,900-175,000 BTU
  • Maximum water flow: 9.4 GPM
  • Thermal efficiency: 94%
  • Temperature range: 100-140 F (commercial C 950 ESC models can reach up to 180 F)
  • Accuracy: +/- 2 F
  • Maximum exhaust and combustion air pipe lengths - 63 ft. for twin pipe system or 43 ft. for concentric
  • Vent size: 3 or 4 inch
  • Maximum altitude 8,000 ft.
  • Minimum water flow to activate: 0.5 GPM
  • Water pressure: min 30, max 145 PSI
  • Size: 11” X 18” X 30.5”, Weight: 74 lbs


Bosch provides a warranty of 15 years on the heat exchanger and 5 years on all other parts. The life expectancy of the water heater is over 20 years.


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