Bosch GL4S Ariston 4-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater Review



The Bosch GL4S Ariston 4-gallon point-of-use electric mini tank water heater is yet another top drawer model from Bosch and Ariston, two of the biggest names in the water heater market. The GL4S is one of the most flexible mini tank water heaters that you will ever find. You can either install it independently, or in-line with a bigger water heater.

Since it’s a point-of-use water heater, you don’t have to worry about installation, because it features a plug and play system. Yes, by simply plugging in the Bosch Ariston GL4S, it’s good to use under your sink, and can store 4 gallons of hot water; more than enough for regular use. The GL4S has been received well by consumers, so let’s take a look at the features that make it worth the purchase.

Bosch GL4S Ariston Indoor Mini Tank   Water Heater

Important Specs and Features

The Bosch Ariston GL4S 4 gallon point of use electric mini tank water heater is fairly simple to install and use. All it takes is tapping the water heater into the cold water line and it will deliver hot water directly to your sink. The plugs require a standard 120 volt outlet that is easily found in most homes and workplaces around the world. The GL4S can heat 4 gallons of water while only consuming 12.5 amps.

The Bosch Ariston GL4S comes with a pressure relief valve that regulates the flow of water. The water heater, despite the fact that it can store 4 gallons of water, is only 17 pounds and has 14 x 14 x 12^1/4 measurements. In the mini tank water heater market, The GL4S definitely stands out for its lightweight and compact size. The tank is glass lined and provides better insulation than most water heaters. This as a result delivers instant hot water without consuming too much energy.

The water heater features a new temperature control knob over its predecessor and allows you to increase or decrease temperature from 65°F to 145°F. It also features an improved thermostat with a sensing probe to adjust and maintain temperatures quicker on a consistent basis. While it’s not a direct replacement of GL4, the GL4S definitely draws comparison from it.

The Ariston GL4S comes with a 6 year warranty on tank, and 1 year limited warranty on all its parts. It can easily be mounted on a wall or floor, and meets the ASHRAE 90.1 standards. The glass lined tank and the Italian design definitely make it a durable water heater in a market where durability is hard to come by at such a price.


  • Cost effective and energy efficient.
  • Lightweight and compact for easy portability.
  • Can work independently and compliment existing water heating systems as well.
  • Provides instant hot water supply with regulated pressure.
  • Ideal for homes and workplaces.
  • Fairly easy to install and use.
  • New and improved thermostat and temperature control knob.


  • Limited water supply – only practical for sinks.
  • Users have complained about the complex yearly maintenance.

Who Should Buy

This is a very interesting question and has more than one answer. To begin with, the Bosch Ariston GL4S 4 gallon point of use indoor mini tank water heater is ideal to use with a sink, and not a shower. This makes it practical in homes where there is an already existing water heating system. It can be used as a side unit to offer you additional 4 gallons of hot water storage. If not, it can be used independently on sinks to wash dishes and perform other household chores.

Is the GL4S practical for workplaces? That depends on what the purpose of use is. Installing and allocating a space for GL4S is not a hassle, so it can easily be kept in a cabinet under the kitchen sink in an office. If a water filter is installed, then the GL4S will help in making coffee or tea much quicker.


The Bosch Ariston GL4S is definitely an improvement over GL2.5S and the GL4. The new thermostat has increased the range of temperature that you can choose for the water. The glass lined interior provides unbelievable insulation and can help you lower your water heating energy bills in the long run.

If you have an existing water heating system in your home and it’s not able to meet your needs, then the Bosch Ariston GL4S is the ideal mini tank water heater to have. You won’t have to break the bank to purchase the water heater as it is quite affordable despite its strong features.

The storage capacity ensures that you get instant hot water supply constantly. While some users have suggested that the maintenance is not as simple as installation, we must say that it’s a once a year job. Overall, the Bosch Ariston GL4S is a good mini tank water heater that lives up to its bill.