Bosch Aquastar 2400ES Review

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The detailed review of Bosch Aquastar 2400ES. Approved as the Energy Star, Bosch Aquastar hot water heaters from 2400 series are among the highest energy-efficient models and are recommended for two bath homes.

Bosch Aquastar 2400ES Features

High Efficient

Bosch Aquastar 2400ES models are not only providing high efficient water heating but with the energy factor of 0.82 they are the Energy Star approved, and therefore, qualified for the government tax credit of 30%, on the purchase and installation.

Aquastar 2400ES is factory set to work on natural gas and with the correct conversion kit they can use propane gas. In both cases they are designed with the maximum gas input of 175,000 Btus/hr and with the water flow rate of 6.4 gallons per minute they deliver enough hot water for two major applications, such as shower and dishwasher, at the same time.

Flexible installation

aquastar 2400 esBosch Aquastar 2400ES are the versatile units as their wall-mount installation, vertical and horizontal venting, provides much-needed flexibility for its owners. Small and lightweight design frees the floor space which would be occupied by the tank-type unit.

Thanks to the direct room-sealed combustion they can be installed indoor so when using twin-pipe system and built-in power-vent, no worries as one pipe expels the flue gases out and uses the other pipe for getting the fresh air in. One pipe venting system is also available but the adequate quantity of the fresh air should be supplied.

If you are still afraid of having the gas inside the house or the outside is simply the best spot for your Bosch Aquastar 2400ES water heater, just order the vent kit AQOK and install the unit outside (for regions not affected by the severe weather conditions).

Aquastar tankless hot water heaters as other tankless units are working on demand and provide an endless hot water as long as you have an unobstructed supply of water, gas and electricity. The gas valve changes its output based on the demand and thanks to the modulating control, Aquastar 2400ES can work in a range from the minimum power of 19,900 Btus to its maximum of 175,000 Btu so less fluctuation in water temperature is present and more comfort you get.


Bosch Aquastar 2400 models are equipped with the high efficient gas burner and heat exchanger for the maximum performance and reduced emission of greenhouse gases. The energy efficiency of 0.82 is what makes these units eligible for government tax credits and utility rebates. Energy Star approval brings 30% reduction on the unit purchase and installation, plus close to 50% decrease on utility costs (stated by Bosch for tankless water heaters).

Regular maintenance such as the sediment removal through the flushing, cleaning the vent system, heat exchanger fins and combustion chamber can maximize the performance, extend the heater's life and provide savings.

Control panel

Aquastar 2400ES is equipped with the very useful control panel at the front-bottom of the unit. This control panel has the control buttons such as the power, program key, reset button, UP and DOWN and the LCD display. The LCD display is consisted of the several indicators such as temperature, error, power, flame, lock and remote indicator. An optional remote control TSTAT2 is handy for wireless control and monitoring of your hot water.

Safety features

  • Built-in water heater freeze protection

  • Pressure relief valve supplied with the water heater

  • Over-heat prevention

  • Ionization flame rod sensor for flame failure

  • Inlet and outlet temperature sensors

  • Backflow temperature sensor

  • Protection against water drop - IP X4

Bosch Aquastar 2700ES is designed for heating potable water only, not for space heating and not for manufactured and mobile homes.


  • Gas input: 19,900-175,000 Btu for NG and LP

  • Maximum gas output: 147,000 Btus

  • Ignition: Electric

  • Dimensions: 30 1/2' x 17 3/4" x 11 1/4"

  • Weights: 67 pounds

  • Electric supply: 120 V

  • Gas and water connection: 3/4" male NPT

  • Water pressure: min. 30 PSI; max. 150 PSI

  • Minimum flow rate: 0.65 GPM

  • Selection range: 100-140 F

  • Noise level: 45-65 dBA

  • Exhaust vent size: 3" stainless steel

  • Combustion air pipe: 3" PVC, Al or galvanized.

  • Warranty: 12-year on heat exchanger

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At first there was a few Glitches but It has been supplying Hot water year round since for 4 years now. It is the most comfortable shower you can take …

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