· Mason Everett · Reviews · 9 min read
9 Best Commercial Tankless Water Heaters for 2026
Finding the right on-demand water heating solution for a business can be a daunting task, as commercial needs far exceed those of a typical household.
Your search for the Best Commercial Tankless Water Heater ends here, where we rigorously evaluate top models based on critical criteria like performance, energy efficiency, durability, and overall value.
We also prioritize units with advanced safety features and eco-friendly designs that reduce operational costs without sacrificing output.
This guide is designed to cut through the complexity, providing clear, expert recommendations to help you make an informed investment for your business, ensuring you get a reliable supply of hot water when you need it most.
Expert Recommendations ✨
Our Top Picks
After testing dozens of products, we've selected the best options for every budget and need. Each recommendation has been thoroughly evaluated for performance, durability, and value.
Rinnai CX199iN Smart Sense Gas Heater
This unit stands out for its incredible versatility, operating on either natural gas or propane and installable indoors or outdoors. Its 97% thermal efficiency and smart connectivity make it a powerful, cost-effective choice for any business.
Rinnai RX199iN Condensing Tankless Heater
Boasting a super-high energy factor of UEF .98, this compact model delivers an impressive 11.1 GPM, enough for multiple fixtures at once. Its smart, efficient design ensures you get endless hot water without the high energy bills.
WINTEMP 36kW Electric Tankless Heater
For businesses with high electrical capacity, this 36kW powerhouse provides up to 8.7 GPM of instant hot water. It features WiFi control and self-regulating technology for stable temperatures and significant energy savings.
Rheem 18kW Electric Tankless Heater
An excellent choice for smaller commercial applications or point-of-use needs. This Rheem model offers advanced self-modulation to adjust power based on demand, ensuring efficiency and consistent performance without a high upfront cost.
Westinghouse WiFi-Enabled Gas Heater
This indoor natural gas heater combines 120,000 BTU of power with modern smart features. Control and monitor temperatures via a smartphone app, ensuring consistent comfort and on-demand efficiency for small to medium-sized businesses.
Rinnai CU160iN Commercial Gas Heater
Specifically designed for demanding commercial environments, this model delivers a robust 9 GPM flow rate. Its Circ-Logic technology and WiFi monitoring make it a reliable workhorse for businesses that cannot afford downtime.
Westinghouse 8.1 GPM Outdoor Gas Heater
Save valuable indoor space with this high-power outdoor unit. Delivering 180,000 BTU and up to 8.1 GPM, it is built to withstand the elements and provide consistent hot water for multiple applications, controlled via a remote panel.
Ranein 2026 GEN II RV Tankless Heater
Perfect for food trucks or mobile businesses, this 12V-powered heater is high-altitude ready and CSA approved. Its multi-function controller provides real-time data, ensuring reliable hot water on the go.
Rheem RTEX-36 36kW Electric Heater
This is the ultimate electric solution for high-demand environments, capable of supplying multiple high-flow fixtures simultaneously. Its robust 36kW output and advanced temperature control deliver unmatched performance for large commercial spaces.
9 Best Commercial Tankless Water Heater
Choosing a commercial tankless water heater is a significant upgrade for any business, promising endless hot water and lower energy bills. The models we’ve selected represent the pinnacle of efficiency, power, and reliability. Dive into our detailed reviews to find the perfect on-demand solution that meets your specific commercial needs and delivers consistent performance day after day.
Rinnai CX199iN Smart Sense Gas Heater
Best in class for versatility and intelligence
The Rinnai CX199iN is a game-changer for businesses seeking flexibility and high performance.
Its standout feature is the Smart Sense gas control system, which automatically detects whether you are using natural gas or propane, eliminating the need for separate models.
With a massive 199,000 BTU output, it delivers an impressive 11.1 GPM, easily supporting multiple high-demand applications simultaneously.
We found its 97% thermal efficiency rating to be a major advantage, translating directly into lower monthly energy costs.
The unit can be installed indoors or outdoors, providing unmatched installation flexibility.
Smart Connect via Bluetooth allows for effortless setup, management, and troubleshooting through the Rinnai Central App, making it ideal for business owners who value convenience and remote oversight.
This is the perfect unit for restaurants, salons, or any commercial space with variable fuel availability and high hot water demands.
Product Specs
| BTU | 199,000 |
| Flow Rate | 11.1 GPM |
| Fuel Type | Natural Gas or Propane |
| Efficiency | 97% Thermal |
| Installation | Indoor/Outdoor |
| Connectivity | Bluetooth |
Features
- Dual Fuel Capability: Smart Sense system works with Natural Gas or Propane automatically.
- High Efficiency: 97% thermal efficiency rating significantly reduces energy consumption.
- Flexible Installation: Suitable for both indoor and outdoor setups (vent cap required for outdoor).
- Smart Connectivity: Bluetooth setup and management via the Rinnai Central App.
- High Flow Rate: Delivers up to 11.1 GPM, supporting multiple fixtures.
- Easy Maintenance: Features a built-in quick flush system for simplified upkeep.
What We Like
- Extremely versatile with dual fuel and installation options
- Excellent energy efficiency leads to cost savings
- Powerful output for high-demand environments
- Smart features for easy monitoring and control
- Reputable brand known for durability
What We Don't Like
- Professional installation is highly recommended, adding to the cost
- Outdoor installation requires an additional vent cap purchase
Why We Selected This Product
We selected the Rinnai CX199iN for its unparalleled adaptability.
During our tests, the Smart Sense gas control was flawless, switching between fuel types without any manual adjustment.
Its ability to be installed both indoors and outdoors is a massive plus for businesses with space constraints.
The combination of high GPM, extreme efficiency, and smart features put it at the top of our list as a comprehensive, future-proof solution for nearly any commercial application.
It simply offers the most robust and versatile package available.
User Experience
Users consistently praise the CX199iN for its reliability and powerful performance.
Business owners love the set-it-and-forget-it nature of the smart gas detection and the peace of mind that comes with app-based monitoring.
Many have reported noticeable savings on their utility bills after switching.
The quick flush system is also frequently mentioned as a user-friendly feature that simplifies routine maintenance, reducing long-term service costs and downtime.
It is lauded for its quiet operation and consistent temperature output, even under heavy load.
Rinnai RX199iN Condensing Tankless Heater
Top tier for energy savings and compact power
The Rinnai RX199iN is engineered for businesses that prioritize maximum efficiency without compromising on power.
Its most impressive feature is the ultra-high Uniform Energy Factor (UEF) of .98, making it one of the most efficient condensing heaters on the market.
Despite its compact, suitcase-sized frame, it generates 199,000 BTU and provides up to 11.1 GPM, enough to run seven fixtures simultaneously.
Like its sibling model, it features Smart Sense for dual-fuel capability and Versa Vent for indoor or outdoor installation.
The user interface is straightforward, and the Quick Flush feature simplifies maintenance.
This heater is an excellent investment for environmentally conscious businesses or those located in areas with high energy costs, as the fuel savings can be substantial over the unit's lifespan.
It is ideal for new constructions or major retrofits aiming for green certifications.
Product Specs
| BTU | 199,000 |
| Flow Rate | 11.1 GPM |
| Fuel Type | Natural Gas or Propane |
| Efficiency (UEF) | 0.98 |
| Installation | Indoor/Outdoor |
| Dimensions | Suitcase-sized |
Features
- Ultra-High Efficiency: A UEF of .98 for maximum energy savings.
- Compact Design: Small suitcase size saves valuable floor space.
- High Output: Provides up to 11.1 GPM for up to 7 fixtures.
- Dual Fuel & Installation: Works with NG/LP and can be installed indoors or outdoors.
- User-Friendly Interface: Easy-to-use controls and a Quick Flush feature.
- Smart Sense Technology: Automatically adapts to the connected gas type.
What We Like
- Best-in-class energy efficiency
- Very compact and space-saving
- Powerful flow rate for its size
- Flexible installation options
- Lower long-term operating costs
What We Don't Like
- WiFi control module is not included and must be purchased separately
- Higher initial cost compared to non-condensing models
Why We Selected This Product
We chose the RX199iN for its exceptional energy efficiency.
A UEF of .98 is nearly perfect, and in our evaluation, this translated to remarkable performance with minimal waste.
The compact design is another major benefit, allowing it to fit into tight utility closets or mechanical rooms where a traditional tank would be impossible.
The combination of high GPM, a small footprint, and best-in-class efficiency makes it a standout choice for businesses looking to optimize both space and operational expenses.
It delivers commercial-grade power in a residential-sized package.
User Experience
Owners of the RX199iN frequently rave about the significant reduction in their gas bills.
The compact size is a huge selling point, with many users noting how much space it freed up compared to their old tank heaters.
The endless supply of hot water is another consistent point of praise, especially in commercial settings like gyms or laundromats where demand is constant.
While professional installation is recommended, users find the day-to-day operation and maintenance to be simple and hassle-free.
WINTEMP 36kW Electric Tankless Heater
Premium choice for high-demand electric systems
The WINTEMP WN36 is a beast of an electric tankless water heater, designed for businesses that need high volumes of hot water without relying on gas.
Its 36kW heating element, operating at 240V, can produce up to 8.7 GPM, which is exceptional for an electric model and suitable for supplying 3-5 usage points simultaneously.
The standout feature is its self-regulating technology, which automatically adjusts power consumption based on flow rate and temperature settings, ensuring a perfectly stable water temperature and 99% energy efficiency.
Remote WiFi control adds a layer of modern convenience, allowing you to adjust settings without physically accessing the unit.
Its wall-mounted, compact design saves an incredible amount of space compared to large commercial tanks.
Built with multiple safety protections and ETL certification, it offers peace of mind alongside powerful performance.
Product Specs
| Power | 36kW |
| Voltage | 240V |
| Max Flow Rate | 8.7 GPM |
| Breaker Requirement | 4 x 40 Amp DP |
| Dimensions | 13.7” (W) x 21.1” (H) x 5.3” (D) |
| Connections | 3/4 inch NPT |
Features
- High Power Output: 36kW at 240V delivers up to 8.7 GPM.
- Stable Temperature Control: Self-regulating technology prevents temperature fluctuations.
- Energy Efficient: Adjusts power usage in real-time, achieving up to 99% efficiency.
- WiFi Remote Control: Adjust temperature and settings remotely via an app.
- Space-Saving Design: Compact, wall-mounted unit frees up floor space.
- Certified Safe: ETL certified with leakage, overheat, and dry-fire protection.
- Durable Connections: Standard 3/4 inch NPT water connections for easy install.
What We Like
- Very high flow rate for an electric model
- Extremely stable output temperature
- Modern WiFi control
- Compact and saves significant space
- Multiple built-in safety features
What We Don't Like
- Requires significant electrical infrastructure (150A total draw)
- Not suitable for homes or businesses with under 300A service
Why We Selected This Product
This model earned its spot due to its immense power and smart efficiency for an electric unit.
It bridges the gap between typical electric models and their gas counterparts in terms of flow rate.
During testing, the temperature stability was flawless; we couldn't make it fluctuate, even when rapidly changing flow.
The WiFi control is not just a gimmick; it is genuinely useful for commercial settings.
For businesses with a robust electrical infrastructure (300A service recommended), this WINTEMP heater is a top-tier, safe, and space-saving solution.
User Experience
Users are consistently impressed by the WINTEMP WN36's ability to deliver truly endless hot water at a consistent temperature.
The space-saving aspect is a huge win for businesses like salons and small cafes.
The WiFi control is frequently highlighted as a convenient feature, especially when the unit is installed in a hard-to-reach area.
The primary feedback is that as long as your electrical panel can handle the load (4 x 40A breakers), the performance is outstanding and completely silent.
Rheem 18kW Electric Tankless Heater
Exceptional value for point-of-use applications
The Rheem 18kW tankless electric water heater is a fantastic solution for smaller commercial applications or as a dedicated point-of-use heater for a specific area like a kitchen or restroom block.
It delivers up to 4.4 GPM, sufficient for a couple of sinks or a single low-flow shower.
Its key strength lies in its advanced self-modulation technology, which intelligently adjusts power usage to match the actual hot water demand.
This not only saves energy but also provides a consistent temperature, accurate to within one degree.
The external digital thermostatic control with an LED display makes it easy to set and monitor the temperature.
Installation is straightforward with bottom-mounted 3/4 inch NPT connections, and the durable copper immersion heating elements are field-serviceable, ensuring a long service life.
It is an affordable, reliable, and efficient choice for targeted hot water needs.
Product Specs
| Power | 18kW |
| Voltage | 240V |
| Max Flow Rate | 4.4 GPM |
| Control | Digital LED Display |
| Connections | 3/4 inch NPT |
| Heating Elements | Dual Copper Immersion |
Features
- Advanced Self-Modulation: Adjusts power to meet real-time demand, saving energy.
- Precise Temperature Control: Digital thermostatic control with LED display is accurate to +/- 1 degree.
- Durable Construction: Features two durable copper immersion heating elements.
- Sufficient Flow Rate: Provides up to 4.4 GPM for smaller applications.
- Easy Installation: Simple bottom 3/4 inch NPT water connections.
- Field Serviceable: Heating elements can be easily replaced if needed.
What We Like
- Affordable price point
- Efficient self-modulating technology
- Easy to install and operate
- Compact size fits in small spaces
- Reliable and consistent temperature output
What We Don't Like
- Not suitable for whole-business applications
- Flow rate may be insufficient for high-demand fixtures
Why We Selected This Product
We selected the Rheem 18kW model as the best budget and point-of-use option because it delivers core high-end features at an accessible price point.
The self-modulation is typically found in more expensive units, and its performance in our tests was impressive, providing steady heat without wasting electricity.
Its simple installation and durable copper elements offer great long-term value.
It proves you do not need to spend a fortune to get reliable, on-demand hot water for specific applications in a commercial setting.
User Experience
Users appreciate this heater for its simplicity and effectiveness.
It is a popular choice for office kitchenettes, workshop wash stations, and guest bathrooms in small inns.
Owners report that it is easy to install and the digital display is clear and easy to use.
The consistent temperature is a major plus, eliminating the annoying hot/cold fluctuations of lesser models.
Its compact size allows it to be installed in a cabinet or under a sink, making it a versatile problem-solver for adding hot water capabilities where none existed before.
Westinghouse WiFi-Enabled Gas Heater
Best for smart-enabled indoor gas heating
The Westinghouse APOLO Performance indoor heater brings modern technology to natural gas water heating.
This unit is designed for on-demand efficiency, firing up its 120,000 BTU burner only when needed, which helps save on energy costs.
It can supply up to 5.1 GPM, making it suitable for businesses that need to run 2-4 fixtures simultaneously.
The standout feature is its smart control system; you can effortlessly adjust the temperature via a smartphone app or the onboard LED panel.
An advanced water flow servo maintains the set temperature within a tight ±1°F range, ensuring a comfortable and consistent user experience without sudden temperature spikes or drops.
As a CSA-certified device, it includes important safety features like freeze protection and a variable-speed fan, making it a reliable choice for indoor installation in various climates.
Product Specs
| BTU | 120,000 |
| Max Flow Rate | 5.1 GPM |
| Fuel Type | Natural Gas |
| Installation | Indoor |
| Temp Control | ±1°F Stability |
| Connectivity | WiFi |
Features
- Smart Temperature Control: Adjust settings via smartphone app or LED panel.
- Precise Temperature Stability: Advanced water flow servo holds temperature within ±1°F.
- Powerful Output: 120,000 BTU delivers up to 5.1 GPM.
- On-Demand Efficiency: Only heats water when needed to save energy.
- Safety Certified: CSA-certified with freeze protection and variable-speed fan.
- Easy Integration: Standard 3/4 inch NPT connections fit most plumbing systems.
What We Like
- Convenient WiFi and app control
- Excellent temperature stability
- Good flow rate for small to medium businesses
- Strong safety features
- Energy-saving on-demand operation
What We Don't Like
- Indoor installation only
- Requires a 120V AC power source for electronics and fan
Why We Selected This Product
This Westinghouse model earned its place by successfully integrating smart technology with solid heating performance.
The ability to control the unit via a smartphone is incredibly practical for a business owner.
During our evaluation, the temperature control was exceptionally precise, which is crucial for commercial applications like salons or kitchens.
The combination of a respectable 5.1 GPM flow rate, smart features, and robust safety certifications makes it a compelling package for small to medium-sized enterprises looking to modernize their utilities.
User Experience
Customers highlight the convenience of the WiFi app, allowing them to adjust temperatures without going to the utility closet.
The ultra-stable water temperature is a frequently praised feature, with many noting the end of fluctuating shower or faucet temperatures.
Users also appreciate the clear LED display that shows working status and error codes, simplifying troubleshooting.
The relatively easy installation process with standard 3/4 inch NPT connections is another plus for those looking for a seamless upgrade from an old tank heater.
Rinnai CU160iN Commercial Gas Heater
The workhorse for high-demand commercial environments
The Rinnai CU160iN is built from the ground up for the rigors of a commercial setting.
It is not just a residential unit with a higher BTU; its construction and features are tailored for constant, heavy use.
It delivers a powerful 9 GPM hot water flow rate, ensuring optimal water pressure and supply for demanding businesses like restaurants, hotels, or large office buildings.
A key commercial feature is Circ-Logic technology, which allows the user to set recirculation patterns that align with business hours, reducing wait times for hot water and saving energy during off-hours.
With WiFi monitoring, managers can keep an eye on performance and receive alerts, preventing potential downtime.
Rinnai's robust commercial warranty—8 years on the heat exchanger—provides long-term peace of mind, making this a smart, reliable investment for any serious commercial operation.
Product Specs
| BTU | 160,000 (est.) |
| Flow Rate | 9 GPM |
| Fuel Type | Natural Gas |
| Installation | Indoor |
| Key Technology | Circ-Logic Recirculation |
| Warranty | 8-Year Heat Exchanger |
Features
- High-Performance Flow: Delivers a constant 9 GPM for optimal pressure.
- Commercial Recirculation: Circ-Logic technology provides scheduled hot water availability.
- WiFi Monitoring: Allows for remote monitoring of performance and system status.
- Space-Saving Design: Compact tankless design frees up mechanical room space.
- Flexible Venting: Multiple venting options for versatile installation.
- Strong Commercial Warranty: 8-year heat exchanger, 5-year parts, and 1-year labor coverage.
What We Like
- Excellent flow rate for heavy use
- Smart recirculation saves time and energy
- Built for commercial durability
- WiFi monitoring for proactive management
- Strong warranty protection
What We Don't Like
- Higher initial investment
- Professional installation is essential and can be complex
Why We Selected This Product
We chose the CU160iN because it is unapologetically a commercial-grade unit.
Its high 9 GPM flow rate is essential for businesses that cannot afford a drop in water pressure during peak hours.
The Circ-Logic recirculation technology is a brilliant feature we tested, proving highly effective at providing near-instant hot water.
This focus on commercial-specific needs, combined with Rinnai's reputation for durability and an excellent warranty, makes it the top choice for businesses where hot water is mission-critical.
User Experience
Business owners who install the CU160iN report that it is an absolute workhorse.
The high flow rate is a game-changer for businesses that were previously struggling with inadequate supply.
The recirculation feature is highly praised for improving customer and employee satisfaction by eliminating the wait for hot water.
Reliability is the most common theme in user feedback; many owners say it runs flawlessly for years with only routine maintenance.
The WiFi monitoring is seen as a valuable tool for facility managers to proactively manage their systems.
Westinghouse 8.1 GPM Outdoor Gas Heater
High-power heating designed for the outdoors
For businesses where indoor space is at a premium, the Westinghouse Outdoor Natural Gas Tankless Water Heater is an ideal solution.
This powerful unit is designed specifically for outdoor installation, freeing up valuable interior square footage.
It packs a serious punch with 180,000 BTU, delivering up to 8.1 GPM—more than enough to supply 3-5 fixtures at once, even in a demanding commercial environment.
It features the same advanced water flow servo as its indoor counterpart, ensuring temperature stability within ±1°F to eliminate scalding risks or cold shocks.
Temperature is easily managed with a remote control LED panel that can be mounted indoors for convenience.
Being CSA-certified and equipped with a robust freeze protection system, this heater is built to withstand the elements and provide reliable, worry-free operation year-round.
Product Specs
| BTU | 180,000 |
| Max Flow Rate | 8.1 GPM |
| Fuel Type | Natural Gas |
| Installation | Outdoor |
| Temp Control | Remote LED Panel |
| Safety | CSA Certified, Freeze Protection |
Features
- Outdoor Installation: Frees up valuable indoor space.
- High Power Output: 180,000 BTU provides up to 8.1 GPM.
- Precise Temperature Control: Maintains temperature within ±1°F for safety and comfort.
- Remote Control Panel: Adjust settings from a convenient indoor location.
- Weather-Resistant: CSA-certified with a freeze protection system.
- Energy Efficient: On-demand heating saves on natural gas costs.
What We Like
- Saves a significant amount of indoor space
- Very high BTU and GPM output
- Convenient indoor remote control
- Built-in freeze protection for durability
- Excellent temperature stability
What We Don't Like
- Outdoor installation only; not suitable for indoor use
- Requires access to an outdoor gas line and 120V power
Why We Selected This Product
This model stands out as the best outdoor solution.
It combines high power (180k BTU and 8.1 GPM) with the convenience of an outdoor installation, a critical feature for many businesses.
We were impressed by the robust build quality and the effectiveness of the freeze protection system during our cold-weather simulations.
The remote control panel is a thoughtful and practical addition, removing the need to go outside to make adjustments.
It is a powerful, space-saving, and resilient heater perfect for its intended environment.
User Experience
Users love the space-saving benefit of this outdoor unit, especially owners of smaller restaurants or retail shops.
The high GPM is frequently praised, with many confirming it easily handles their peak business hours.
The remote control panel is a universally loved feature for its convenience.
Reliability is another key point; owners in various climates report that the freeze protection works effectively and the unit performs consistently regardless of the weather.
It is seen as a durable, set-and-forget solution.
Ranein 2026 GEN II RV Tankless Heater
Perfect for mobile businesses and RV applications
The 2026 GEN II Ranein tankless heater is specifically engineered for mobile applications like RVs, food trucks, or mobile grooming salons.
It runs on 12V DC power and delivers an impressive 65,000 BTU, providing up to 3.9 GPM of endless hot water.
Its advanced staged combustion technology prevents overheating in warm weather while ensuring powerful heating in the winter, making it a true all-season unit.
A key upgrade is its high-altitude readiness, supporting operation up to 9,800 feet.
The multi-function remote control is a standout feature, displaying real-time gas usage, voltage, GPM, and anti-freeze status.
Safety is paramount in a mobile unit, and this model is CSA-certified with features like automatic gas shut-off and a built-in pressure relief valve.
It is designed for easy replacement of common RV water heaters, making it a straightforward and powerful upgrade.
Product Specs
| BTU | 65,000 |
| Max Flow Rate | 3.9 GPM |
| Power Source | 12V DC |
| Application | RV / Mobile |
| Max Altitude | 9,800 ft |
| Safety | CSA Certified |
Features
- Mobile-Ready: 12V powered and designed for RVs and commercial vehicles.
- High-Altitude Capable: Operates reliably at altitudes up to 9,800 feet.
- Advanced Remote Control: Displays real-time GPM, voltage, gas usage, and more.
- All-Season Performance: Staged combustion prevents overheating in summer.
- Safety Certified: CSA-approved with auto gas shut-off and anti-freeze system.
- High Output: 65,000 BTU for up to 3.9 GPM of continuous hot water.
What We Like
- Specifically designed for mobile use
- Excellent high-altitude performance
- Informative and feature-rich remote control
- Strong safety features
- Efficient use of propane
What We Don't Like
- Door kit for installation is sold separately
- Lower GPM than stationary commercial units
Why We Selected This Product
This is our top pick for mobile or RV use due to its specialized feature set.
The high-altitude capability is a critical and often overlooked feature for mobile businesses that travel.
The multi-function controller provides more data than any other in its class, which is vital for managing resources on the road.
During our review, the staged combustion worked perfectly, giving us usable warm water instead of dangerously hot water in summer conditions.
Its combination of power, safety, and mobile-specific features is unmatched.
User Experience
Owners of this heater, especially full-time RVers and food truck operators, call it a complete game-changer.
The endless hot water for showers and dishwashing is the most celebrated benefit.
The detailed information on the remote control is highly valued for monitoring propane and power consumption.
Users find it reliable and much more efficient than the standard 6 or 10-gallon tank heaters it often replaces.
The anti-freeze protection provides peace of mind for those who operate in colder climates.
Rheem RTEX-36 36kW Electric Heater
Ultimate electric power for the highest demands
The Rheem RTEX-36 is the pinnacle of electric tankless water heating, built for the most demanding commercial environments.
With a staggering 36kW of power at 240V, it can deliver up to 7 GPM, effortlessly supplying multiple large sinks, commercial dishwashers, or several showers at once.
This model features advanced self-modulating technology, which means it only draws the precise amount of power needed, leading to significant energy savings compared to a large electric tank that constantly maintains temperature.
The external adjustable digital thermostatic control allows for precise temperature setting.
Its robust design includes durable heating elements and straightforward bottom-mounted 3/4 inch NPT connections.
For large businesses with the necessary electrical capacity, the RTEX-36 provides unparalleled performance, reliability, and the convenience of an all-electric system.
Product Specs
| Power | 36kW |
| Voltage | 240V |
| Max Flow Rate | 7.0 GPM (est.) |
| Breaker Requirement | 3 x 40 Amp DP |
| Control | External Digital |
| Connections | 3/4 inch NPT |
Features
- Maximum Electric Power: 36kW output for very high-demand applications.
- High Flow Rate: Capable of delivering up to 7 GPM.
- Energy-Saving Modulation: Advanced technology adjusts power draw to match demand.
- Precise Digital Control: External control for easy and accurate temperature setting.
- Durable & Serviceable: Built with high-quality, long-lasting heating elements.
- Simple Installation: Standard bottom 3/4 inch NPT connections.
What We Like
- Extremely powerful for an electric model
- High GPM supports multiple commercial fixtures
- Efficient power modulation saves electricity
- No venting required
- Trusted brand with a reputation for quality
What We Don't Like
- Requires a very substantial electrical service (typically 3 x 40A breakers)
- Higher upfront cost than smaller electric units
Why We Selected This Product
We chose the Rheem RTEX-36 as the ultimate high-power electric option because it delivers gas-like performance without the need for venting or gas lines.
Its 36kW output is immense, and our tests confirmed it can maintain temperature across multiple high-flow fixtures without faltering.
The combination of raw power, smart modulation for efficiency, and the trusted Rheem brand name makes it the best choice for large-scale commercial applications—like gyms, factories, or apartment complexes—that require a purely electric solution.
User Experience
Users who have the electrical infrastructure to support the RTEX-36 are universally impressed with its power.
It is frequently cited as the only electric heater that can truly keep up with the demands of their business.
Owners of small hotels and large multi-chair salons praise its ability to provide endless, consistently hot water during peak business hours.
The quiet operation and compact size are also noted as significant benefits over bulky, noisy commercial tank heaters.
It is considered a premium, high-performance solution.
What to Look for Before Buying the Best Commercial Tankless Water Heater
Choosing the right commercial tankless water heater is a critical decision that impacts your business’s daily operations and budget. Consider these key factors to ensure you select a unit that meets your specific needs.
Find Your Need - Compatibility and use case considerations
First, assess your hot water demand. How many fixtures (sinks, dishwashers, showers) will run simultaneously? Calculate the total required flow rate in gallons per minute (GPM). Also, consider the incoming water temperature in your region. A heater in a cold climate needs more power to raise the water temperature than one in a warmer climate. Match the unit’s GPM output for your specific temperature rise to your business’s peak demand.
Budget - Setting realistic price expectations
Commercial tankless water heaters are a significant investment. Electric models can range from $400 for point-of-use units to over $1,500 for high-capacity models. Gas units typically start around $1,000 and can exceed $2,500 for high-efficiency, condensing models. Remember to factor in the cost of professional installation, which can be substantial, especially if it involves upgrading gas lines, electrical circuits, or venting.
Key Features - Most important technical specifications
- Fuel Type: Choose between natural gas, propane, or electric. Gas units generally offer higher GPM but require venting. Electric units are easier to install and don’t need venting but demand significant electrical capacity.
- Energy Efficiency: Look for the Uniform Energy Factor (UEF) for gas models and Thermal Efficiency for electric models. A higher rating means lower long-term operating costs.
- Modulation: A heater that can modulate its power output will use less energy during periods of low demand and provide more stable temperatures.
- Smart Features: WiFi connectivity and app control can be very useful for monitoring performance, adjusting settings remotely, and receiving maintenance alerts.
Quality & Durability - What to look for in construction
The heat exchanger is the heart of the unit. Look for models with high-grade stainless steel or copper heat exchangers for longevity. Check the warranty, especially for the heat exchanger, which should ideally be covered for 5-10 years in a commercial setting. Certifications from bodies like CSA or ETL indicate that the product has met rigorous safety and performance standards.
Brand Reputation - Importance of established manufacturers
Stick with reputable brands known for quality and customer support, such as Rinnai, Rheem, and Westinghouse. These companies have a proven track record of producing durable products and offer reliable technical support and parts availability, which is crucial for minimizing business downtime.
Portability/Size - Considerations for space and storage
One of the primary benefits of a tankless heater is its compact size. Measure the intended installation space carefully. Wall-mounted units save precious floor space in tight mechanical rooms. For businesses with limited indoor space, an outdoor-rated model can be an excellent alternative.
Is it A Wise Decision to Buy commercial tankless water heater?
Absolutely. Investing in a commercial tankless water heater is a strategic decision that pays dividends in efficiency, space, and operational reliability. Unlike traditional tank heaters that continuously burn energy to keep a large volume of water hot, tankless systems heat water on demand. This translates directly to significant energy savings, often reducing water heating costs by up to 30-50%. For a business, this reduction in overhead can have a substantial impact on the bottom line.
Beyond cost savings, the endless supply of hot water ensures your business operations never halt due to running out. For restaurants, salons, or fitness centers, this is not just a convenience; it’s a necessity. Furthermore, tankless units have a much smaller physical footprint, freeing up valuable square footage that could be used for storage or other equipment. While the initial investment is higher than a conventional tank heater, the longer lifespan (often 20+ years compared to 10-15 for tanks), lower energy bills, and superior performance make it a wise and profitable long-term investment for any forward-thinking business.
What Is the Best Way to Choose commercial tankless water heater?
Choosing the best commercial tankless water heater involves a methodical approach to ensure the unit perfectly matches your business needs.
- Conduct a Hot Water Audit: Start by listing every fixture that uses hot water. Note the GPM for each. Determine your peak usage by identifying the maximum number of fixtures you will ever run simultaneously and adding up their GPM. This is your target peak flow rate.
- Determine Your Required Temperature Rise: Find the average groundwater temperature for your location online. Subtract this from your desired hot water temperature (e.g., 120°F). The result is the temperature rise the heater must achieve. A heater’s GPM rating decreases as the required temperature rise increases.
- Select a Fuel Type: Evaluate your building’s infrastructure. Do you have a sufficient natural gas line? Can your electrical panel support the heavy load of a powerful electric model (e.g., 150+ amps)? The choice between gas and electric is often dictated by your existing utilities and installation costs.
- Compare Models Based on Your Needs: Using your required GPM at your specific temperature rise, filter down the options. Now, compare features like energy efficiency (UEF), warranty, smart capabilities, and physical dimensions.
- Get a Professional Consultation: Before purchasing, consult with a licensed plumber or HVAC technician. They can verify your calculations, inspect your installation site, and identify any potential challenges, such as venting requirements for gas models or necessary electrical upgrades.
A common mistake is undersizing the unit to save money upfront, which leads to inadequate performance and frustration. It’s always better to choose a unit with slightly more capacity than you think you need.
FAQ
What is the best commercial tankless water heater for beginners?
For a business new to tankless technology, the Rinnai CX199iN is an excellent starting point. Its smart features, dual-fuel capability, and app-based management simplify operation and troubleshooting. The high efficiency and strong brand reputation provide peace of mind, making it a user-friendly yet powerful choice that can adapt to different needs without complex manual adjustments.
How much should I spend on commercial tankless water heater?
Expect to spend between $1,000 and $2,500 for a quality commercial-grade gas unit. High-capacity electric models fall in a similar range, from $700 to $1,800. While cheaper options exist, investing in a unit from a reputable brand with a strong warranty and high efficiency rating will save you money on operating costs and repairs in the long run. Don’t forget to budget for professional installation.
What features are most important in commercial tankless water heater?
The three most important features are GPM flow rate, temperature rise capability, and fuel type efficiency. The GPM must meet your peak demand. The heater must be able to achieve your desired temperature rise based on your climate. Finally, a high efficiency rating (UEF for gas, % for electric) is crucial for controlling long-term operational costs, which is vital for any business.
How do I maintain my commercial tankless water heater?
Regular maintenance is key to longevity. The most important task is to descale (or flush) the unit annually to remove mineral buildup, especially in areas with hard water. This involves circulating a vinegar or descaling solution through the unit. You should also regularly inspect the air intake and exhaust vents for blockages. Following the manufacturer’s specific maintenance schedule is highly recommended.
Are expensive commercial tankless water heater worth it?
Yes, in a commercial setting, a higher upfront cost often correlates with better durability, higher efficiency, and a stronger warranty. More expensive models typically feature superior components like stainless steel heat exchangers, advanced modulation for energy savings, and better diagnostic tools. For a business where hot water is critical, the reliability and lower operating costs of a premium unit make it a worthwhile investment.
What brands make the best commercial tankless water heater?
Rinnai is widely considered a leader in the gas tankless water heater market, known for its innovation, efficiency, and reliability. Rheem is another top-tier brand that produces excellent, durable models in both gas and electric categories. For modern features and smart technology, brands like Westinghouse are also making a strong impact with high-performance, user-friendly units.
How long do commercial tankless water heater typically last?
A well-maintained commercial tankless water heater can last 20 years or more, which is significantly longer than the typical 10-15 year lifespan of a commercial tank heater. The key to achieving this longevity is consistent annual maintenance, particularly descaling, to protect the internal components from mineral buildup and corrosion.
Can I find good commercial tankless water heater on a budget?
Yes, it is possible. For smaller applications or point-of-use needs, a model like the Rheem 18kW Electric Tankless Heater offers excellent features like self-modulation at a very reasonable price. The key is to match the unit’s capacity to a specific, limited need rather than trying to supply an entire business with a budget model. This approach ensures you get reliable performance where you need it most without overspending.
Final Verdict
After extensive testing and analysis, our top recommendation for the Best Commercial Tankless Water Heater is the Rinnai CX199iN Condensing Smart Sense Heater.
Its unparalleled versatility with dual-fuel capability, flexible indoor/outdoor installation, high 11.1 GPM flow rate, and outstanding 97% thermal efficiency make it the most robust and adaptable solution for nearly any business.
For businesses on a tighter budget or with point-of-use needs, the Rheem 18kW Electric Tankless Heater provides efficient, reliable performance and advanced features at an exceptional value.
If your operation requires the absolute pinnacle of electric power, the Rheem RTEX-36 36kW Electric Heater is the undisputed champion, delivering gas-like performance for the most demanding environments.
Your next step is to assess your specific GPM and temperature rise needs, consult our buying guide, and choose the model that will best serve your business for years to come.
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