Bosch Ariston Water Heaters Review

Bosch Ariston water heaters are small, space-saving tank-type electric units, designed for point-of-use service and fast, hot water delivery. Explore the available models, its features, and benefits.

Available models

There are three sizes of the smallest Bosch water heaters that store hot water in mini tanks and use electricity for heating:

  • Ariston Pro GL2.5Ti S
  • Ariston Pro GL4CA S / GL4Ti S
  • Ariston Pro GL8Ti

Ariston Pro GL2.5Ti S

Ariston Pro GL2.5Ti S is the smallest water heater, designed for serving one fixture only. With the size of 14" x 14" x 10¼" it weighs 15.5 lbs only so that it can be installed on the wall with the supplied bracket or floor. With the tank capacity of 2.7 gallons, it is used solely for small jobs.

Ariston Pro GL4CA S / GL4Ti S

Ariston Pro GL4CA S / GL4Ti S is nearly the same size as the above model, except it is 2" thicker: 14" x 14" x 12¼"`, and heavier by almost

2 lbs. Its tank size is by one gallon bigger: 3.85 gallons. Both models do not require any complicated installation except mounting, as they are using the plug-in cable connection.

Ariston Pro GL8Ti

Ariston Pro GL8Ti, with its 17½" x 17½" x 14½" and weight of 29.5 lbs is almost as twice heavier as previous models. Thanks to the 7.0-gallon tank capacity GL8Ti can provide enough hot water for two fixtures at the same time. Since the unit does not have the plug-in connection, the installation requires some hands-on knowledge. Installation is as easy as with the other two models and can be piped either horizontally or vertically.


Easy installation

All Ariston models are small and lightweight, so installation is very easy and simple. It just requires you to bring the cold water pipe in, the pipe for outgoing hot water and 120 v plug.

Due to its compact size, the best location is in the kitchen or bathroom, under the sink so that it can provide hot water for hand and face washing or fast dishwashing. The water inside the tank is always ready, and with the short pipe length, you will have instant hot water. There will be no minimum water flow required for activation as in tankless models.


The tank capacity is limited, but you can combine any of the three Ariston water heaters with the bigger heater that has much more in capacity. Combining them in in-line setting, not only that you will have a lot of water, but hot water will be available instantly.


Ariston water heaters are equipped with one heating element that has a power of 1440 Watts so the units can provide 6.8 GPH recovery rate and have the thermal efficiency of 98%, which means that very low heat is lost.

Thermostat and temperature

The temperature can be regulated by using the thermostat which is found behind the front panel so that the temperature can be adjusted from

65 to 145 F. The water heaters are protected from the extremely high temperatures and pressure. If the temperature exceeds the 190 F high limit switch will shut down the unit, while the TPR valve opens when the pressure inside the tank exceeds allowable.


The metal tanks in all Ariston water heaters are protected with the glass lining and the magnesium anode rod, so there will be less danger from the aggressive water action, and that allows Bosch to provide a decent 8-year warranty.

Ariston water heaters might be small and simple, but they are also subjected to sediment build-up, either on the heating element on the tank`s bottom, anode rod degradation, and other problems. Regular maintenance such as descaling or anode replacement is needed for high performance and long life.


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