Bosch Gas/Electric Tankless Water Heater Reviews, Cost and Buying Guide 2021

Before you dive into the specific brand review, we highly recommend you to read our elaborate Tankless Water Heater Reviews and Tankless Water Heater Installation Cost Guide in advance. There are several crucial steps you need to take before you even start to think about the brand.

Our Bosch tankless water heater guide reviews gas and electric, whole-house and point of use water heaters. Our comprehensive review includes all models, their specifications including GPM flow rates and Bosch tankless water heater prices.

We’ve made it easy to compare tankless water heater brands using our reviews for Bosch and:

Introduction to Bosch Tankless Water Heaters

Bosch is a Global 500 company with a huge presence in automotive, appliance, automation, HVAC, tools and similar sectors. With global headquarters in Germany, Bosch has operations including factories throughout North America.

The company makes Bosch gas water heaters and electric models too. Gas models come fitted with a valve for natural gas (NG), but it can be replaced during installation for use with propane (LP).

This table shows all Bosch tankless water heaters and their specs.

Bosch Gas Tankless Water Heater Models

BTU InputEfficiencyMax.
9900 Series
E.F. 0.998.7/7Built-inIndoorOptional15 years
9800 Series
E.F. 0.998.7/7NoEitherOptional15 years
C 1050 ES
199KE.F. 0.9510.7OptionalEitherNo15 years
C 950 ES
199KE.F. 0.9594OptionalEitherNo15 years
C 1210 ES
225KE.F. 0.9812.1OptionalEitherNo15 years
940 ES
199KE.F. 0.839.4NoEitherNo15 years
830 ES
175KE.F. 0.828.3NoEitherNo15 years

Bosch Electric Tankless Water Heater.xlsx

Series/ModelKilowattsEfficiencyMax. GPMWiFiCirculatingWarranty
Tronic 5000 C WH3636kWE.F. 0.975.4NoNo5 years
Tronic 6000 C WH2727kWE.F. 0.973.5NoNo5 years
Tronic 6000 C WH1717kWE.F. 0.972.3NoNo5 years
Tronic 3000 C US1212kWE.F. 0.981.8NoNo5 years
Tronic 3000 C US99.5kWE.F. 0.981.4NoNo5 years
Tronic 3000 C US77.2kWE.F. 0.981.1NoNo5 years
Tronic 3000 C US66kWE.F. 0.980.9NoNo5 years
Tronic 3000 C US33.2kWE.F. 0.980.5NoNo5 years

Important Note on Max. GPM: This column represents the maximum gallons per minute flow rate the heater can produce. Maximum GPM flow is achievable only when the incoming water is quite warm. The colder the incoming water is, the longer it must be heated to reach the thermostat setting on the tankless water heater, so the lower the GPM flow rate will be. In tankless water heater specifications, you’ll see information such as “Flow rate @ 70°F temp rise is 4.3 GPM.” That’s from a unit with Max. GPM of 7.5 GPM and means that if the temperature of the incoming water must be raised by 70 degrees Fahrenheit to reach the thermostat setpoint, then only 4.3 gallons per minute of hot water can be expected. For more information on this important topic, see the related section in our Tankless Water Heater Buying Guide.

  • Efficiency: Bosch lists model efficiency as the Energy Factor (EF), a rating that was replaced recently by Uniform Energy Factor(UEF). Most brands list both, as you can see in our guides to Rinnai and Navien, for example. The UEF is typically 2-3 percent below EF, so keep that in mind as you compare Bosch tankless heaters to other brands you’re considering.
  • Low-NOx: Therm 9000 models are Low-NOx for use where emission restrictions are in place. The Therm C 1210 ES is also low-NOx plus meets California SCAQMD requirements.
  • Warranty: The 15-year warranty coverage for gas models is on the heat exchanger. A general parts warranty of 5 years applies.
  • Electric whole house: Bosch calls the Tronic 5000 and 6000 models whole-house models, but understand their limits. The WH36 will supply a 3-bathroom house, but only in warm climates where inlet water temperature is 70+ degrees Fahrenheit. It’s rated for two bathrooms in a moderate climate and one in a cool climate. The WH27 is rated for one (cool climate) or two (warm climate) bathrooms, but not cool climates. The WH17 is rated for one bathroom in a warm climate only. Complete details are found in the Bosch electric tankless water heater brochure.

Bosch Features Analysis

Bosch tankless water heater features worth comparing with Navien, Rinnai and other top brands include:

Greentherm 9900 and 9800 Series water heaters have stainless steel secondary heat exchangers for maximum corrosion resistance.

The Greentherm 9900 Series includes a built-in recirculating pump. For maximum benefit of this feature, additional piping is required. A small amount of heated water is recirculated from the water heater to designated sources like a sink faucet or shower.

The Bosch Therm C 1210 ES Series has an aluminum heat exchanger. This cuts down on cost but is slightly less resistant to corrosion as stainless steel.

The Tronic 3000 Series includes three point-of-use models with mini-tanks. The 3000 T ES8 (7gal), ES4 (4gal) and ES2.5 (2.7gal) tanks allow a reserve of hot water to be available for immediate use and a higher flow rate than true tankless models produce.

The Therm C 1210 is a cascading series. Up to 24 units can be linked together when larger volumes of hot water are needed.

How Bosch Water Heaters Compare to Other Tankless Brands

The Bosch company is far larger than most other producers of tankless water heaters including Rinnai, Takagi, Navien and even Rheem and makes a huge range of parts and equipment.

Like Rheem, EcoSmart and a few other brands, Bosch manufacturers both gas and electric models. Its models get ratings from mediocre to good, not excellent. Some think this reflects a huge company that doesn’t give just one division of many the attention it deserves.

Bosch Tankless Heater Prices

Bosch units are dependable and efficient, especially Bosch residential gas models, but they don’t have as many high-performance and convenience features as Navien and Rinnai. How do they compare on price? This table and pricing tables in our other guides make them easy to compare.

Bosch Gas Models
Unit Cost Only
Greentherm 9900 Wifi199k
Greentherm 9900199k
Greentherm 9900160k
Greentherm 9800199k
Greentherm 9800160k
Greentherm C 1050 ES199k
Greentherm C 950 ES199k$1,200-$1,400
Therm C 1210 ES225k$1,875-$2,200
Therm 940 ES199k$1,250-$1,575
Therm 830 ES175k$1,050-$1,175
Bosch Electric Models
Unit Cost Only
Tronic 5000 C WH3636
Tronic 6000 C WH2727
Tronic 6000 C WH1717
Tronic 3000 C US1212
Tronic 3000 C US99
Tronic 3000 C US77
Tronic 3000 C US66$150-$195
Tronic 3000 C US33$140-$185

The range of prices is from various online and local sellers. Higher costs sometimes reflect free shipping included. When shipping is not included in the cost, expect it to be an additional $50-$85 for gas models, less for electric units. The different prices are a reminder that it pays to shop around.

Bosch Tankless Water Heater Installation Cost

You have options for professional installation. Unlicensed handyman services cost the least followed by licensed handyman services and certified, licensed plumbers charging the most. Bosch has a reputation for denying warranty claims when the unit wasn’t installed by a licensed plumber or according to strict specifications. Because of the risk of shock (electric units) or explosive gas leaks or deadly carbon monoxide leaks with gas units, the best practice is to hire a licensed plumber with good experience installing tankless water heaters.

Installation cost ranges from less than $600 to about $1,500 depending on the scope of the project. Costs are higher for gas water heater installation, but gas units have lower operating costs. Factors that make installation costlier include:

  • Installation of a gas line
  • Installation of piping for hot water recirculation
  • Installation of a 208/240V line
  • Installation of a 50-amp fuse or new electrical panel to handle multiple electric units
  • Venting indoor units
  • The Bosch outdoor installation kit ($80-$100)

When looking for a top professional installer in your area, consider using our Free Local Quote tool. The service is free to use. The contractors that provide written quotes are licensed, experienced and prescreened. They know they’re competing for the work, so provide the lowest estimates possible.

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