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Home » Water Heaters » Bosch Tankless Water Heater Reviews

Bosch Tankless Water Heater Reviews

By: David Trinh
Last Updated:

Bosch is a Global 500 company that produces a wide range of electronics, including many home appliances.

Its Thermotechnology division is responsible for water heaters and other HVAC appliances for the home. Bosch manufactures a variety of hot water heaters (gas and electric), most at a mid-range price and with high energy efficiency.

In this review we will take a look at Bosch’s top water heaters to help you decide if this is a brand you should consider purchasing from.

Top 5 Bosch Tankless Water Heaters

Bosch C 1210 ES
  • 12.1 GPM
  • Gas, Whole House
  • Indoor or Outdoor
  • 0.98 Energy Factor Rating
  • 8.7 GPM
  • Gas, Whole House
  • Indoor
  • 0.99 Energy Factor Rating
6000 C WH17
  • 2.3 GPM
  • Electric, Point of Use
  • Indoor
  • 0.97 Energy Factor Rating
6000 C WH27
  • 3.5 GPM
  • Electric, Point of Use
  • Indoor
  • 0.97 Energy Factor Rating
830 ES
  • 8.3 GPM
  • Gas, Whole House
  • Indoor or Outdoor
  • 0.82 Energy Factor Rating

About Bosch

Robert Bosch established the Bosch company in 1886. Since then, the company has grown to become one of the most important manufacturers in the world, making far more appliances than almost any other water heater producer. It operates in 50 countries around the world through 350 subsidiary companies.

Where Are Bosch Water Heaters Made?

Bosch is based in Gerlingen, Germany, but it has factories across the globe. It even makes some of its water heaters in North America.

Types of Bosch Water Heaters

Tankless water heaters from Bosch come in three series: Therm and Greentherm for gas models and Tronic for electric models. All the gas models work with natural gas, but it is possible to convert them to use propane at installation.

The gas water heaters from Bosch come in a range of sizes, the largest of which provide enough hot water for multiple appliances at once — sufficient even for multi-family homes. The electric water heaters are more suited for apartments or as point-of-use units. Whatever model you choose, you can expect to see a significant drop in utility costs due to the high energy efficiency.

Bosch Tankless Water Heater Reviews from Consumers

Consumers appreciate that Bosch tankless water heaters eliminate the risk of a cold sandwich when showering. Customers also love that they receive hot water almost immediately after turning on the faucet.

However, what they appreciate most is the cost savings. Although Bosch water heaters may have a higher upfront cost than some other brands, they also offer unbeatable energy  efficiency — especially the top gas models.

Installing Bosch Water Heaters

Installation of Bosch water heaters varies greatly according to the model. The simplest point-of-use heaters are by far the easiest to install — it can be just the case of plugging the heater into a power outlet. Other electric heaters have a slightly more complicated process, but anyone with basic HVAC skills is likely to manage.

Gas water heaters, on the other hand, always require the expertise of a professional technician. This is because of safety concerns when working with gas. In fact, if you receive an installation service from an unlicensed handyman, you’ll void your warranty. Make sure the HVAC professional you hire adheres to the strict specifications Bosch sets out.

The complexity and cost of installing a gas model will depend on factors like whether you already have a gas line and whether you require venting (this is the case for indoor units). You will also incur additional expenses if you need to purchase an outdoor installation kit or if you want to include recirculation.

Bosch Water Heater Problems and Maintenance

Bosch tankless water heaters rarely suffer from problems, due to the long durability of the patented heat burner. This same technology leads to a higher efficiency than you’ll find with many other brands. If you do experience any problems, the issue should be easy to fix thanks to the advanced diagnostic system.

To maximize the lifespan of the water heater, you’ll also need to carry out proper maintenance. With an electric water heater, this means occasional cleanings to remove sediment. Gas heaters are slightly more complicated. You’ll need to receive a checkup from an HVAC technician on an annual basis to ensure your heater is working safely and not releasing any dangerous gases. However, you can manage the cleaning yourself.

You’ll find specific recommendations and further guidance for maintenance for the particular model in the heater’s user manual.

Customer Service for Bosch Water Heaters

Bosch has dedicated customer service for its tankless water heaters through its Thermothechnology department. It has separate phone lines for its residential and commercial products, as well as fax numbers. Alternatively, you can email the department: there are separate email addresses for customer support, technical support, warranty and returns, and commercial products. Finally, you can reach out to Bosch on all the top social media platforms.

Warranty for Bosch Tankless Heaters

 All the water heaters from Bosch are designed to last at least 20 years. The gas water heaters (those in both the Greentherm and the Therm series) come with a 15 year warranty on the heating element — this is much longer than the industry standard. Electric water heaters have a shorter warranty of 5 years. All the water heaters also come with a 2-year warranty on other components.

Therm Series

Models in the Therm series come with a scale prevention system to improve maintenance. This is combined with a dual fan, modulating vertical burner, and built-in turbulators, all of which further reduce scale buildup in heat exchangers.

C 1210 ES Model

A condensing unit, the C 1210 ES works by using a pre-mix combustion process, which increases energy efficiency. In fact, the C 1210 ES is one of the most efficient of all Bosch tankless water heaters. Although electric water heaters typically have a higher efficiency than their gas counterparts, Bosch managed to obtain a 0.98 energy factor for this model.

With the C 1210 ES, you receive up to 12.1 GPM of hot water — more than is necessary for most homes, even in cold climates. For businesses with high hot water needs, it is possible to use the C 1210 ES in a cascade to link as many as 24 units together.

The C 1210 E has an aluminum heat exchanger for corrosion resistance. Although aluminum is less effective than stainless steel, the lower cost of the metal brings down the price of the water heater. Like all the other Bosch condensing gas heaters, the C 1210 ES has a secondary heat exchanger made of aluminum and copper.

Being low NOx means the heater is environmentally friendly, the cost of venting pipes is lower, and you have more options as to where you can install the heater — both indoors and outdoors. You also have the option to add a recirculating pump, which will recirculate heated water from the heater to somewhere like a sink or shower.

830 ES Model

A non-condensing unit, the 830 ES can heat water up to 140 degrees Fahrenheit. It provides up to 8.3 GPM with a temperature rise of 35 degrees Fahrenheit, making it ideal for a large home in a warm climate. As flow is less for cooler incoming water, it is likely enough for just an average home in a cold climate. Alone, the 830 ES is also suitable for light commercial applications, but you can always combine up to 24 units for greater hot water needs.

The 830 ES is reliable at providing a continuous stream of water at the temperature you set. Its automatic ignition system combined with the patented gas design helps improve energy efficiency. You can install the heater either indoors or outdoors — although if you choose to have it outdoors, you will need an installation kit. It is even suitable for outdoor installation in cold climates, thanks to freeze protection.

Greentherm Series

Like Therm water heaters, the models in the Greentherm series have a digital control panel. Here, you can set the thermostat, monitor temperature rise, access safety controls, and check error codes. The heaters also have vertical modulating gas burners to make the burning of gas cleaner and to prevent temperature fluctuations.

9900 Model

One of the most high-tech water heaters from the Greentherm series, the 9900 comes with the option to add WiFi capabilities for greater control. In addition, with an energy factor rating of 0.99, it is even more energy efficient than the 1210 ES. The heater comes with a stainless steel secondary heat exchanger to improve its resistance to corrosion and it has a recirculating pump built in. To make the most of this feature, it is recommendable to install additional piping.

The 9900 is a condensing unit and low NOx, meaning it is better for the environment than some of the other gas models. Although it is only possible to install the heater indoors, the procedure is less expensive than installing a condensing unit indoors due to the lack of complex venting requirements.

Tronic Series

Although Bosch calls its Tronic 5000 and 6000 water heaters whole-house models, the low GPM and temperature rise of most of these units means they are unlikely to provide enough hot water for most homes.

The largest of all the heaters in the Tronic series provides just 5.4 GPM, which is enough for a small home in a cool climate and average-size home in a hot climate. (The heater is rated for two bathrooms in a mild climate and one bathroom in a cold climate.) All the other heaters supply sufficient hot water for up to about three appliances in hot climates, meaning they are better suited as point-of-use units.

The smallest water heaters in the Tronic series are 3000 models. They provide between about 0.5 GPM and 2 GPM. Some of these are tankless, whereas others come with mini tanks to hold a small quantity of hot water, therefore increasing flow rate.

6000 C WH17 Model

The 6000 C WH17 provides 2.3 GPM. As it is rated for only one bathroom in a warm climate, you’ll need to look for a different model if you live in a northern state. The benefits of the 6000 C WH17 include an electronic flow sensor and element modulation to control water temperature.

The compact size of the 6000 C WH17 means that you can install it almost anywhere indoors. You can mount it on the wall in the kitchen or bathroom, tuck it away in a cupboard, or fit it under the sink. As it requires no ventilation, you have plenty of options.

6000 C WH27 Model

Offering up to 3.5 GPM, the 6000 C WH27 is more powerful than the 6000 C WH17. Still compact, you have plenty of flexibility for installation. The heater is rated for one bathroom in a mild climate and two bathrooms in a warm climate, but, again, it is unsuitable for cold climates. You’ll also need at least a 200-amp service, but you can have voltage anywhere from 208 to 240 volts.

With an energy factor rating of 0.97, the 6000 C WH27 is one of the most efficient models on the market. Not only is heat loss minimal, the water heater has a built-in sensor and power modulation to ensure it only supplies the hot water you need and prevent power fluctuations.

A useful feature of the 6000 C WH27 is the filter screen over the water inlet, which avoid dirt, dust, and particles entering the heater and damaging the heating elements. Plus, it uses a solid copper heat exchanger to reduce corrosion. For safety, it has a cutout system, which activates if the water temperature rises too high.

Where to Buy Bosch Water Heaters

Amazon has a wide range of Bosch water heaters for sale, all at reasonable prices. You can find all the models named above in the top five, as well as others in the Therm, Greentherm, and Tronic series. These other models tend to differ just in GPM and other minor details.

Lastly, if you still want to compare other brands before purchasing, see our guide here.

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David Trinh
David is an expert in all things plumbing, heating, cooling, and water treatment. He got his start in the plumbing business working on fixing all types of home improvement issues including water leaks, broken toilets, appliance installation, and more. Over time, he learned a ton about installing and choosing the correct water treatment products for homeowners.

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