Best Commercial Tankless Water Heaters: Top 10 Picks

The best commercial tankless water heater delivers endless hot water on demand for high-usage businesses, ensuring customer satisfaction and operational efficiency. Selecting the perfect unit involves considering flow rate, energy source compatibility, and installation requirements specific to your commercial space. A mismatched selection can lead to costly performance issues or, worse, insufficient hot water during peak times, negatively impacting your business.

Factors like gas versus electric models, ventilation needs, and multiple unit setups also play a significant role in long-term satisfaction. To help you navigate these crucial choices, we’ve compiled a list of the top 10 commercial tankless water heaters currently available, focusing on reliability, efficiency, and robust performance for demanding environments.

The best commercial tankless water heater often prioritizes energy efficiency and flexible installation, with models like the Rinnai CX199iN and Rinnai CU160iN offering indoor/outdoor Versa Vent compatibility and Smart Sense gas control for natural gas or propane. For electric options, Rheem provides durable copper immersion heating elements with precise +/- 1 degree temperature accuracy, as seen in the 18kW 240V model.

Best Commercial Tankless Water Heater: Top Picks at a Glance

Image	Product	Buy
Best Pick 1	Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane Best for: Commercial installations	Check Price
Best Pick 2	NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Best for: High-demand sites	Check Price
Best Pick 3	Rheem 18kW 240V Tankless Electric Water Heater, Gray Best for: Electric-only needs	Check Price
Best Pick 4	Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY Best for: Small residential	Check Price
Best Pick 5	Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Best for: Natural gas homes	Check Price

How We Picked

We prioritized build quality, real-world performance, safety, durability, and standout features when selecting the best commercial tankless water heater options for Rinnai’s condensing models, like the CX199iN and RX199iN, impressed with their indoor/outdoor versatility and Smart Sense gas control. We favored units offering precise temperature control and robust heating elements, such as the Rheem electric and gas models.

While some Rheem units were ideal for residential use, we focused on those with higher GPM for commercial demand. Models lacking robust safety certifications or notable efficiency features were ruled out.

What Most Buyers Get Wrong

Gas vs. Electric: Commercial Capacity Considerations

When selecting a commercial tankless unit, the fuel source is paramount. High-demand environments benefit from the robust performance of natural gas or propane, often indicated by BTU ratings like the 160,000 BTUs found in Rheem RTG models. Electric options, such as the Rheem 18kW or Westinghouse 14kW, may have limitations on flow rate and may require significant electrical infrastructure upgrades, making them more suitable for lower-demand applications or specific site constraints.

Always verify local utility capabilities and cost-effectiveness.

Understanding Commercial GPM Requirements

Commercial settings demand a consistent hot water supply for multiple simultaneous uses. Flow rate, measured in Gallons Per Minute (GPM), is the critical spec. For instance, Rheem RTGH Series models can offer up to 8.4 GPM, ideal for busy restaurants or multi-stall restrooms.

Conversely, a unit like the Westinghouse Electric 14kW has a maximum flow rate of 3.38 GPM, better suited for smaller commercial spaces with fewer simultaneous hot water needs. Ensure the GPM meets peak demand to avoid customer dissatisfaction.

1. Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane

Best for: Versatile indoor/outdoor use, high efficiency.

Operating on either natural gas or propane, this Rinnai tankless water heater features a Smart Sense gas control system, allowing for versatile installation indoors or outdoors, powered by 600 watts and 120 volts, delivering 11.1 GPM.

With an impressive 97% thermal efficiency, this unit significantly reduces operational costs. It can reach a maximum temperature of 185 degrees Fahrenheit and supports a maximum pressure of 150 PSI, ensuring consistent hot water delivery.

Pros

• 370,000 BTUs for high-demand heating
• 97% thermal efficiency
• 11.1 GPM flow rate
• Smart Sense gas control system

Cons

• Requires a separate RX-OVC vent cap for outdoor installation.

This Rinnai model is ideal for commercial properties needing flexible installation options and high-efficiency heating. Businesses requiring consistent hot water for multiple uses will benefit from its robust performance.

2. NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane

Best for: Compact, high-flow, smart-control gas heater.

This Rinnai condensing tankless water heater is powered by gas and designed with a compact, suitcase-like size, delivering up to 11 GPM, making it suitable for businesses that need efficient hot water in a small footprint.

Featuring Smart Sense gas control and Versa Vent technology, it operates on propane or natural gas. This unit boasts a heat output of 199,000 BTUs and an efficiency rating of UEF .98, ensuring optimal energy usage up to 140 degrees Fahrenheit.

Pros

• 11 GPM flow rate
• Compact size
• Versa Vent technology
• Smart Sense gas control

Cons

• Maximum temperature limited to 140 degrees Fahrenheit.

Ideal for businesses with limited installation space but high hot water demands. Its efficiency and smart controls make it a strong choice for restaurants or small facilities needing reliable on-demand hot water.

3. Rheem 18kW 240V Tankless Electric Water Heater, Gray

Best for: Powerful electric heating for businesses.

This Rheem electric tankless water heater draws 18000 watts and 240 volts to provide ample hot water, featuring an external digital thermostatic control with LED display for precise temperature management up to 140°F.

With a flow rate of up to 4.4 GPM, it utilizes durable copper immersion heating elements for field serviceability. Its advanced self-modulation adjusts power to meet demand, achieving a 99.8% efficiency rating.

Pros

• 18kW heating capacity
• 99.8% efficiency
• +/- 1 degree accuracy on temperature control
• Durable copper heating elements

Cons

• Requires a 240V electrical connection, which may necessitate electrical upgrades.

This 18kW Rheem electric unit is a solid choice for businesses needing a powerful and efficient electric water heater. Its precise temperature control and self-modulating features are perfect for settings where consistent hot water is critical.

4. Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY

Best for: Efficient electric water heating for moderate needs.

The Rheem RTEX-13 residential tankless water heater uses 13 KW and 240 voltage to deliver hot water on demand, with an external adjustable digital thermostatic control featuring an LED display for precise 1°F temperature adjustments.

Equipped with durable copper immersion heating elements, it offers a flow rate of up to 4.8 GPM and achieves at least 99.8% energy efficiency. The unit includes 1/2 NPT adapters for simple installation.

Pros

• 13kW heating capacity
• Up to 4.8 GPM flow rate
• 99.8% energy efficiency
• Precise 1°F temperature control

Cons

• Flow rate may be insufficient for multiple high-demand fixtures simultaneously.

This Rheem electric tankless water heater suits businesses with moderate hot water needs, such as small offices or retail spaces. Its efficiency and ease of installation make it a practical heating solution.

5. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water

Best for: Indoor natural gas, high-flow water heating.

Powered by 160,000 BTUs of natural gas, this Rheem high-efficiency tankless water heater delivers up to 7.0 GPM, perfect for multi-bathroom homes or businesses with consistent hot water requirements.

Designed for indoor installation, its durable metal cabinet and wall-mounting support ensure longevity. Features like Hot-start Programming and 1/2 Gas Line Compatibility simplify operation and installation for up to 140°F.

Pros

• 7.0 GPM flow rate
• 160,000 BTUs heat output
• Hot-start Programming
• High Energy Efficiency

Cons

• Designed specifically for indoor installation only.

This Rheem RTG-70DVLN-3 is an excellent option for businesses needing substantial hot water from a natural gas source indoors. Settings like small restaurants or clinics will find its 7.0 GPM capacity very effective.

6. Westinghouse Tankless Water Heater Electric 14kW 240V, Instant On-Demand Hot

Best for: Instant hot water with smart home compatibility.

This Westinghouse electric tankless water heater, rated at 14kW and 240V, provides instant on-demand hot water with a maximum flow rate of 3.38 GPM, suitable for single-point-of-use applications.

Featuring ETL certification and smart home compatibility, it works with Google Assistant and Alexa. The unit requires a 60-amp circuit breaker and 6 AWG wire, with a bottom 1/2-inch NPT water connection for installation.

Pros

• 14kW heating power
• 3.38 GPM flow rate
• Smart Home Compatible
• ETL Certified

Cons

• Requires dedicated 60-amp double-pole circuit breaker, potentially increasing installation complexity.

This 14kW Westinghouse electric unit is ideal for businesses needing on-demand hot water at specific locations, like handwashing stations or small kitchens. Its smart home features add convenience for managing usage.

7. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water

Best for: Outdoor liquid propane, high-flow water heater.

Operating on liquid propane with 180,000 BTUs, this Rheem high-efficiency tankless water heater delivers up to 7.0 GPM, designed for outdoor installation to meet the hot water needs of 2–3 bathroom homes or businesses.

This unit is built with a durable metal cabinet and supports easy wall mounting. Its compact and lightweight design, along with industry-best side-to-side clearance, aids installation outdoors, offering reliable hot water up to 140°F.

Pros

• 7.0 GPM flow rate
• 180,000 BTUs heat output
• Designed for outdoor installation
• Compact and lightweight design

Cons

• Powered by liquid propane, requiring a propane tank or supply.

A superior choice for commercial properties or facilities located outdoors requiring reliable hot water powered by propane. Its robust 7.0 GPM output is perfect for multiple simultaneous uses.

8. Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater, Indoor

Best for: Commercial gas heater with Wi-Fi monitoring.

This Rinnai CU160iN commercial tankless water heater uses gas to provide a powerful 9 GPM hot water flow rate, featuring a space-saving design that heats only when necessary to conserve energy.

With Wi-Fi monitoring capabilities and Circ-Logic technology for recirculation, this unit offers optimal water pressure and smart, reliable heating. Its energy efficiency and flexible venting options enhance its commercial suitability.

Pros

• 9 GPM high flow rate
• Wi-Fi Monitoring
• Circ-Logic recirculation technology
• Energy and space efficient

Cons

• Specific efficiency percentage is not provided in the technical details.

This Rinnai CU160iN is an excellent fit for commercial businesses demanding high flow rates and smart operational features. Businesses prioritizing energy savings and remote monitoring will find this unit beneficial.

9. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water

Best for: Outdoor natural gas, efficient water heating.

Designed for outdoor installation, this Rheem high-efficiency tankless natural gas water heater delivers up to 7.0 GPM, powered by 160,000 BTUs for fast, reliable hot water even during peak demand.

It features Hot-start programming, freeze protection, and a low activation flow rate for consistent performance. The durable metal cabinet and wall-mounting support make it suitable for commercial applications requiring outdoor natural gas heating.

Pros

• 7.0 GPM flow rate
• 160,000 BTUs heat output
• Designed for outdoor installation
• Freeze protection

Cons

• Requires outdoor installation, limiting placement options.

This Rheem RTG-70XLN-3 is ideal for businesses needing a robust, outdoor natural gas water heater for consistent hot water supply. Settings like warehouses or service centers will benefit from its 7.0 GPM capacity.

10. Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120

Best for: High-flow, natural gas, indoor applications.

The Rheem RTGH Series tankless water heater offers a flow rate of 0.4 – 8.4 GPM, powered by natural gas to deliver consistent hot water for demanding commercial uses, with available temperature settings from 100 to 140°F.

Featuring Exclusive Hot Start Programming and Overheat Film Wrap, this unit ensures reliable operation. It includes electric ignition and a durable heat exchanger, boasting a 17-11/16-inch width for wall mounting.

Pros

• Up to 8.4 GPM flow rate
• Hot Start Programming
• Electric Ignition
• Durable heat exchanger

Cons

• Minimum activation flow rate is 0.4 GPM, which may not be suitable for very low-flow fixtures.

This Rheem RTGH Series is engineered for businesses that require a high-volume, natural gas water heater for indoor use. Its rapid heating and robust flow rate make it a strong contender for busy commercial environments.

Gas vs. Electric Tankless: The Unseen Cost

When selecting a best commercial tankless water heater, the fundamental decision between gas and electric power sources dictates not just upfront costs, but long-term operational efficiency and installation complexity.

While units like the Rheem RTG-70DVLN-3, RTG-70XLP-3, and RTG-70XLN-3 all offer a robust 7.0 GPM flow rate, powered by either natural gas or propane with substantial BTU ratings, they demand significant venting infrastructure. This gas-powered approach, particularly the condensing Rinnai CX199iN and NEW Rinnai RX199iN with their Versa Vent systems, prioritizes heating power but introduces complexities in exhaust management that electric models bypass entirely. Condensing technology, found in the Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater, offers higher energy efficiency by capturing heat from exhaust gases, a significant advantage over non-condensing models, but it often means a higher initial investment and more intricate installation regarding condensation drainage.

Conversely, electric options such as the Rheem 18kW 240V Tankless Electric Water Heater and the Westinghouse Tankless Water Heater Electric 14kW 240V, along with the Rheem RTEX-13, present a considerably simpler installation profile. They avoid external venting altogether, making them ideal for locations where gas line connections are impractical or where building codes restrict gas appliance venting. However, their heating capacity is directly tied to electrical service limitations.

The Westinghouse unit, for example, has a maximum flow rate of 3.38 GPM and requires a substantial 59A current draw on a dedicated 60-amp circuit, illustrating a critical bottleneck. While Rheem’s electric units sport advanced self-modulation for power adjustment, the sheer electrical demand for high flow rates still makes them less suited for simultaneous, high-volume hot water needs compared to their gas counterparts.

The Rheem RRTGH84DVLN3701171, with its 8.4 GPM, hints at electric capability but even so, many commercial applications requiring consistent high flow will find gas superior.

The choice hinges on prioritizing installation simplicity and avoiding complex venting, which favors electric units for less demanding scenarios, or opting for higher, sustained hot water output that is the hallmark of gas units, despite the added installation and venting requirements. Buyers often underestimate the ongoing cost and logistical challenges of gas venting, leading them to overlook the simplicity and sometimes lower total cost of ownership for electric units in specific contexts.

For businesses needing consistent, high-demand hot water, like a busy restaurant kitchen or a multi-stall shower facility, the Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane unit represents a more robust long-term solution, despite its more involved installation.

What to Look for in a Commercial Tankless Water Heater

Gas vs electric power sources

For commercial use, natural gas tankless water heaters are the superior choice when available due to their higher BTU output and typically lower operating costs, directly translating to higher flow rates suitable for demanding applications. Look for models with at least 199,000 BTUs; anything less will struggle with simultaneous demand. Electric models, while simpler to install with fewer venting complexities, require significant amperage and dual-voltage capabilities to meet commercial needs, often demanding a dedicated high-amperage circuit.

For most businesses, the consistent high performance of a natural gas unit is the decisive factor for efficient operation.

Ventilation and exhaust systems

Proper ventilation is paramount for safe and effective operation. Prioritize direct vent systems for indoor installations, as they draw combustion air from outside and exhaust directly through an exterior wall, minimizing indoor air quality concerns. Power vent models offer more flexibility in placement but still require careful attention to exhaust termination and clearances.

Ensure the chosen unit’s venting materials are corrosion-resistant for longevity. For businesses with ample exterior wall access, direct vent units offer the most robust and safest solution for consistent, worry-free operation.

Flow rate and temperature rise

Matching the heater’s capacity to your peak demand is non-negotiable. Calculate your simultaneous hot water needs by summing the Gallons Per Minute (GPM) requirements of all fixtures that might run at once. A commercial kitchen, for instance, needs a unit capable of delivering at least 10-12 GPM.

Equally important is the temperature rise; a 70°F rise is standard for most commercial applications, ensuring hot water is consistently delivered at the desired output temperature. Select a unit with a GPM/temperature rise combination that exceeds your highest anticipated usage.

Energy efficiency and ecoconsiderations

When evaluating energy efficiency, focus on a high Energy Factor (EF) rating, with .90 and above being excellent for tankless units. Look for features like built-in water recirculation, which significantly reduces water waste and conserves utility resources by delivering hot water faster. While the initial investment for a high-efficiency unit may be higher, the long-term savings on utility bills and reduced water consumption make it the financially sound and environmentally responsible choice for any commercial establishment aiming for operational sustainability.

Which Should You Choose?

• If you need to install the unit in various locations and use either natural gas or propane, choose a model with versatile venting and a Smart Sense gas control system.
• If precise temperature control is a priority for your business, choose an electric model with an external digital thermostatic control featuring +/- 1-degree accuracy.
• If you have high hot water demand for multiple fixtures simultaneously, choose a gas model with a high GPM (gallons per minute) flow rate, like 7.0 GPM or higher.
• If you’re looking for efficient heating that only operates when needed and offers flexibility in installation, choose a condensing tankless water heater with multiple venting options.

Quick Best Commercial Tankless Water Heater Buying Checklist

• Confirm Space Requirements: Ensure enough clearance for installation and maintenance.
• Assess Peak Demand: Calculate the maximum GPM needed simultaneously.
• Determine Venting Needs: Choose between direct vent, power vent, or non-condensing.
• Evaluate Energy Source: Select gas or electric based on availability and cost.
• Check Maximum Temperature Rise: Ensure it meets your hot water needs.
• Review Manufacturer Warranty: Look for comprehensive coverage on parts and labor.

Frequently Asked Questions

How Does Ventilation Differ Between Commercial Tankless Water Heaters?

Commercial tankless water heaters utilize different ventilation methods to safely expel exhaust gases. Direct vent systems draw combustion air from outside and exhaust through a wall, while power vent units use a fan to push exhaust through a pipe, offering more installation flexibility.

What Is The Importance Of Flow Rate For A Commercial Tankless Water Heater?

The flow rate, measured in gallons per minute (GPM), is critical for meeting simultaneous hot water demands in commercial settings. Higher GPM ensures multiple fixtures can operate without a drop in pressure or temperature, crucial for busy environments.

Why Is Temperature Rise A Significant Factor In Commercial Tankless Units?

Temperature rise indicates how much the unit can heat incoming water. Commercial applications often require significant heating of cold water to reach desired temperatures for dishwashers or showers, making adequate temperature rise essential for performance.

Should I Choose Gas Or Electric For My Commercial Tankless Water Heater?

Gas models generally offer higher flow rates and are often more cost-effective to operate, especially with natural gas. Electric models are simpler to install, require no venting, and are a good option where gas isn’t available, though they may have higher running costs.

What Does ‘Energy Factor’ Mean For A Commercial Tankless Unit?

The energy factor (EF) represents a unit’s thermal efficiency, indicating how much fuel is converted to usable heat versus lost. A higher EF signifies greater energy efficiency, leading to lower operating costs for your commercial tankless water heater.

Final Words

Investing in the best commercial tankless water heater provides consistent, on-demand hot water, enhancing operational efficiency. These systems offer significant energy savings and space advantages over traditional units. By carefully considering your specific needs, you can ensure reliable and cost-effective hot water for your business.