Bosch

Bosch is a manufacturer of residential and light commercial tankless water heaters and electric point-of-use water heating equipment. Robert Bosch GmbH was founded November 15, 1886 in Stuttgart, Germany. Bosch entered the heating appliance business in 1932 through the acquisition of Junkers and Co. The water heating and HVAC division operates as the Bosch Home Comfort Group, headquartered in Wetzlar, Germany. In July 2025, Bosch completed an approximately [price removed] acquisition of the residential and light commercial HVAC business from Johnson Controls. The SupplyHouse lineup covers gas tankless units in the Therm, AquaStar, and Greentherm series and electric point-of-use units in the Tronic series. Bosch gas tankless water heaters carry Ultra-Low NOx certification.

Product Lines

Bosch Therm Series Non-Condensing Gas Tankless Water Heaters

Therm 830 ES NG (SKU 7703311076): 175,000 BTU, 8.3 GPM at 35°F rise, 82%+ thermal efficiency (ANSI Z21.10.3), Ultra-Low NOx, CSA listed. Therm 940 ES NG (SKU 7703311075) and 940 ES LP (SKU 7703411073): 199,000 BTU, up to 0.82 UEF, Ultra-Low NOx. Both series support intelligent cascading of up to 24 units for commercial and multi-family applications.

Bosch AquaStar Series Natural Draft Gas Tankless Water Heaters

AquaStar 1600H (NG: SKU 1600H-NG, LP: SKU 1600H-LP): 117,000 BTU, hydro-generated ignition, no electricity or standing pilot required, natural draft venting, 8.75"D x 18.25"W x 29.75"H, 12-year heat exchanger warranty, 2-year parts warranty. AquaStar 1600P (SKU 1600P-NG/LP): same platform with standing pilot ignition. For cabins and installations without electrical service.

Bosch Greentherm Series Condensing Gas Tankless Water Heaters

Greentherm T 9800 SE 199 NG (SKU 7736503581): 199,000 BTU, up to 0.96 UEF (ENERGY STAR), 22:1 turndown, 60 ft venting on 2" or 3" PVC, Ultra-Low NOx, integrated freeze protection. Greentherm T 9900 SE 199 NG (SKU 7736503731): adds built-in recirculation pump, 11.2 GPM at 35°F rise, 15-year heat exchanger warranty, 5-year parts warranty.

Bosch Tronic Series Electric Point-of-Use Tankless Water Heaters

Tronic 3000 C US3: 0.7 GPM at 35°F rise, 98% thermal efficiency, copper heat exchanger and copper-sheathed elements. US9: 1.9 GPM at 35°F rise, same copper construction. Tronic 4000C-10 (SKU 7738007418): 3.5 kW, 96% efficiency, 13" x 8.5" x 4.5". Compact under-sink units for single-fixture point-of-use applications.

Why Contractors Specify Bosch

Plumbing and HVAC contractors specify Bosch because the product line covers the full range of residential gas tankless applications from no-electricity natural draft AquaStar models through high-efficiency condensing Greentherm units at up to 0.96 UEF. Ultra-Low NOx certification across the Therm and Greentherm Series meets California and other regulated market requirements. The Greentherm 9900 carries a 15-year heat exchanger warranty and 5-year parts warranty. Cascading of up to 24 Therm Series units addresses multi-family and light commercial applications. Bosch has been in the heating appliance business since 1932.

How to Choose a Bosch Tankless Water Heater

The most important decision variables are fuel source, venting type, efficiency requirement, and whether electrical service is available. Without electricity: AquaStar 1600H (hydro-ignition) or 1600P (standing pilot), both natural draft in NG and LP. For standard whole-home non-condensing installations: Therm 830 ES NG (175,000 BTU/8.3 GPM) or Therm 940 ES (199,000 BTU, up to 0.82 UEF, NG and LP). For high-efficiency condensing installations qualifying for ENERGY STAR: Greentherm T 9800 SE 199 NG (0.96 UEF, PVC venting). For condensing with built-in recirculation pump: Greentherm T 9900 SE 199 NG (11.2 GPM at 35°F rise, 15-yr heat exchanger warranty). For electric point-of-use under-sink: Tronic 3000 C US3 (0.7 GPM) or US9 (1.9 GPM). For California and Ultra-Low NOx regulated markets, confirm the specific model's certification before specifying.

FAQs

When was Bosch founded and when did they enter the heating business?
Robert Bosch GmbH was founded November 15, 1886 by Robert Bosch in Stuttgart, Germany. Bosch entered the heating appliance business in 1932 through the acquisition of Junkers and Co. The division operates as Bosch Home Comfort Group, headquartered in Wetzlar, Germany.

What is Ultra-Low NOx certification and which Bosch models carry it?
Ultra-Low NOx certification means NOx emissions are below the threshold required by California and other regulated markets. Bosch Therm Series and Greentherm Series gas tankless water heaters carry Ultra-Low NOx certification. Verify the specific model's status before installing in a regulated jurisdiction.

What is the warranty on the Bosch Greentherm 9900 Series?
The Greentherm T 9900 SE 199 NG carries a 15-year heat exchanger warranty and a 5-year parts warranty. The AquaStar 1600H carries a 12-year heat exchanger warranty and a 2-year parts warranty. Warranty terms vary by product line; verify the specific model's warranty at the time of purchase.

What is the difference between the Bosch Therm Series and the Greentherm Series?
The Therm Series uses a non-condensing heat exchanger at 82%+ thermal efficiency. The Greentherm Series uses a stainless steel condensing heat exchanger recovering heat from flue gases, achieving up to 0.96 UEF and ENERGY STAR certification. Greentherm requires PVC venting; Therm allows B-vent or stainless exhaust. Choose Greentherm where maximum efficiency and ENERGY STAR eligibility are priorities.

Can Bosch Therm Series units be cascaded for commercial applications?
Bosch Therm Series units support intelligent cascading of up to 24 units for multi-family and light commercial applications, balancing load across the bank and coordinating ignition sequencing. Consult Therm Series installation documentation for cascading system design requirements.

What is the flow rate of the Bosch Greentherm T 9900 SE 199 NG?
11.2 GPM at a 35°F temperature rise at 199,000 BTU input. Actual delivered flow rate depends on the incoming cold water temperature at the installation location.