The Best Bosch Tankless Water Heaters in 2026: 4 Picks

Quick picks

Our 4 picks

1 Best overall

Bosch 9.4 GPM Natural Gas Tankless Water Heater

Best for: Whole-house hot water demand

Fuel Type

Natural Gas

Flow Rate

9.4 GPM at 35F rise

BTU

199,000 BTU/hr max input

Dimensions

31 x 18 x 12 in

Weight

76 pounds

View on Amazon: Bosch 9.4 GPM Natural Gas Tankless Water Heater Affiliate link

The Bosch 940 ES NG is a high-output natural gas tankless water heater. It delivers 9.4 gallons per minute at a 35°F temperature rise, powered by 199,000 BTUs. This non-condensing unit supports both vertical and horizontal venting with 3-inch or 4-inch stainless steel pipes. Its compact 12-inch depth and 76-pound weight fit standard utility spaces. It suits households needing strong flow for multiple simultaneous uses.

Pros

• 199,000 BTU/hr maximum input
• 9.4 GPM flow rate at 35°F rise
• Flexible vertical or horizontal venting options
• Electronic ignition system

Cons

• 76-pound weight requires sturdy mounting
• Non-condensing design may be less efficient than condensing models
• Natural gas only, not compatible with propane

Good fit if

• You need high flow for whole-house use
• You have existing natural gas lines
• You want flexible venting directions

Skip if

• You use propane fuel
• You need a propane-compatible unit
• You require a condensing model for higher efficiency

Verdict: Bosch 940 ES Natural Gas Tankless Heater delivers robust 9.4 GPM output for busy households. It fits users who need reliable, high-flow hot water and have natural gas access.

2 Best budget

Bosch Therm Propane Tankless Water Heater, 8.3 GPM

Best for: Whole-house propane hot water

Fuel Type

Propane

Flow Rate

8.3 GPM at 35F rise

BTU

175,000 BTU/hr max input

Dimensions

30.5 x 17.9 x 11.3 in

Weight

80 pounds

View on Amazon: Bosch Therm Propane Tankless Water Heater, 8.3 GPM Affiliate link

The Bosch 830 ES LP delivers 8.3 GPM at a 35F rise. It uses 175,000 BTU of propane input. Thermal efficiency stays above 83%. The unit weighs 80 pounds. It measures 30.5 by 17.9 by 11.3 inches. You can vent it vertically or horizontally. This model suits propane users needing high flow.

Pros

• 8.3 GPM flow rate at 35F rise
• 175,000 BTU max input
• 83%+ thermal efficiency
• Vertical or horizontal venting options

Cons

• Propane only; not natural gas
• Heavier at 80 pounds
• Larger footprint than point-of-use models

Good fit if

• You need high flow for whole-house use
• You have propane fuel available
• You want flexible venting directions

Skip if

• You need natural gas fuel
• You want a compact point-of-use unit
• You need electric heating

Verdict: The Bosch 830 ES LP Propane Tankless fits homes with propane lines that need strong hot water flow. It handles multiple fixtures well if you have the space and fuel type.

3 Best 4.0 gallons

Bosch ES4 4-Gallon Mini-Tank

Best for: single sink or small bathroom

Wattage

1440 Watts

Capacity

4 gallons

Voltage

120VAC

Dimensions

12.5" W x 14" D x 14" H

Weight

17.2 pounds

View on Amazon: Bosch ES4 4-Gallon Mini-Tank Affiliate link

The Bosch ES4 is a 4.0-gallon point-of-use water heater with a 1440-watt heating element. It operates on a standard 120VAC plug-in connection. The unit features a glass-lined tank and measures 12.5 by 14 by 14 inches. It weighs 17.2 pounds and mounts to walls or floors. This compact heater suits small spaces like under-sink installations where quick hot water is needed.

Pros

• 4.0-gallon capacity for point-of-use
• 1440-watt heating element
• Standard 120VAC plug-in connection
• Glass-lined tank for durability
• Wall or floor mounting options

Cons

• Limited to point-of-use applications
• 1440 watts may heat slowly for high demand
• No digital display or remote control

Good fit if

• You need hot water for a single sink
• You have a standard 120V outlet nearby
• You want a compact unit under a counter

Skip if

• You need to supply multiple fixtures at once
• You require high-flow hot water for showers
• You only have 240V electrical circuits available

Verdict: Bosch ES4 4-Gallon Mini-Tank provides reliable hot water for small, localized needs. It fits well in tight spaces with standard electrical outlets.

4 Also great

Bosch ES8 7-Gallon Electric Mini-Tank

Best for: single sink or faucet hot water

Fuel Type

Electric

Wattage

1440-watt

Capacity

7.0-Gallon

Voltage

120VAC

Dimensions

17.3 × 14.8 × 17.3 inches

Weight

29.3 pounds

View on Amazon: Bosch ES8 7-Gallon Electric Mini-Tank Affiliate link

The Bosch ES8 is a 7-gallon point-of-use electric water heater designed for quick hot water delivery. It operates on 120VAC with a 1440-watt heating element. The unit features a glass-lined tank for durability and includes a temperature/pressure relief valve. Measuring 14.8 by 17.3 by 17.3 inches, it is compact enough for wall or floor mounting in tight spaces.

Pros

• 7.0-gallon capacity for point-of-use needs
• 120VAC hard-wired connection with 1440-watt output
• Glass-lined tank for long service life
• Wall or floor mounting options

Cons

• Limited to point-of-use applications
• Requires hard-wired electrical connection
• Smaller capacity than whole-house units

Good fit if

• You need hot water for a single sink
• You have limited space for installation
• You want a durable glass-lined tank

Skip if

• You need to heat water for multiple fixtures
• You prefer propane or natural gas fuel
• You require a whole-house solution

Verdict: Bosch ES8 7-Gallon Electric Mini-Tank is a compact solution for single-fixture hot water needs. It fits well in tight spaces where larger units cannot go.

Specifications side by side

Bosch Tankless Water Heater Models

Bosch offers distinct options based on your fuel source and hot water needs. The Bosch 940 ES NG provides 9.4 GPM of natural gas power for whole-house demand. If you use propane, the Bosch 830 ES LP delivers 8.3 GPM with similar robust performance for busy households. These gas units require appropriate venting and fuel access.

For localized needs, Bosch provides compact electric mini-tanks. The Bosch ES4 holds 4.0 gallons, fitting single sinks or small bathrooms. The Bosch ES8 offers 7 gallons for slightly larger single-fixture demands. These electric models plug into standard outlets and fit tight spaces where larger gas units cannot go.

Where Bosch Fits Your Home

Bosch covers two distinct needs. Their gas units handle whole-house flow. The 940 ES NG weighs 76 pounds and measures 18 by 31 inches. The 830 ES LP is slightly heavier at 80 pounds. These gray metal boxes suit busy homes with gas lines. For small spaces, Bosch offers mini-tanks. The 4-gallon ES4 is compact, weighing just 17.2 pounds. The 7-gallon ES8 is larger but still fits tight spots. You will not find large commercial models here. The range stops at residential whole-house gas or single-sink electric. Choose based on your fixture count and fuel type.

How to choose the right Bosch tankless water heater

1. Match your fuel source

   Your home’s existing fuel line dictates which Bosch unit you can install. The Bosch 940 ES NG requires a natural gas connection, while the 830 ES LP is designed for propane lines. You must verify your fuel type before purchasing. Installing the wrong fuel model is impossible and unsafe. Check your current supply first. This spec is non-negotiable for proper operation. It determines the entire system’s compatibility with your home’s infrastructure. Ensure your gas line pressure matches the unit’s requirements for safe and efficient heating.

2. Calculate whole-house flow

   If you need hot water for multiple fixtures simultaneously, check the gallons per minute rating. The Bosch 940 ES NG delivers 9.4 GPM, which supports busy households with high demand. The Bosch 830 ES LP provides 8.3 GPM, which is also strong for whole-house use. You should sum the flow rates of all expected fixtures. If the total exceeds the unit’s capacity, water temperature may drop. Choose a higher GPM model if you run showers and sinks at the same time.

3. Select mini-tanks for sinks

   For single sinks or small bathrooms, a whole-house unit is overkill. The Bosch ES4 is a 4.0-gallon mini-tank designed for localized hot water. It fits in tight spaces and uses standard electrical outlets. The Bosch ES8 offers 7 gallons of capacity for slightly higher demand. These electric models are ideal for point-of-use applications. You save energy by heating water only where it is needed. This approach avoids the long wait times associated with tankless units far from the fixture.

4. Check physical dimensions

   Tankless gas units are large. The Bosch 940 ES NG measures 18 by 31 inches and weighs 76 pounds. The 830 ES LP is 17.9 by 30.5 inches and weighs 80 pounds. You must ensure your installation space can accommodate these dimensions. Mini-tanks are smaller, with the ES4 measuring 12.5 by 14 inches. Measure your closet or utility area before buying. Gas units require clearance for ventilation and service access. Verify that your space allows for proper airflow and maintenance access.

5. Verify electrical requirements

   Electric mini-tanks like the ES4 and ES8 require standard electrical outlets. You do not need special wiring for these small units. However, gas units do not use electricity for heating but may need power for controls. Always check the voltage requirements in the manual. Ensure your outlet is grounded and properly rated. For gas models, verify that you have a gas line and proper venting. These infrastructure checks are critical before installation. Incorrect electrical or gas connections can void warranties and create safety hazards.

Frequently asked questions

See also

• bosch 9 4 gpm natural gas tankless water heater vs therm propane
• bosch 940 es ng tankless water heater review