The best commercial tankless water heater provides an endless supply of hot water and significant energy savings for high-demand businesses. Selecting the right unit ensures operational efficiency and guest or employee satisfaction. Key differences lie in flow rate, heating capacity, fuel type (natural gas vs.
electric), and venting requirements, all impacting performance and installation cost. A poor choice can lead to insufficient hot water during peak times or excessive energy consumption, wasting both operational capacity and financial resources.
To help you make an informed decision, we’ve compiled a list of the top 10 commercial tankless water heaters available, covering a range of specifications and benefits.
The best commercial tankless water heater balances energy efficiency with robust performance, often featuring condensing technology for optimal fuel use. Models like the Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater are praised for their energy-saving design and adaptable venting, suitable for indoor installations where space and efficiency are key considerations.
Best Commercial Tankless Water Heater Picks Compared
| Image | Product | Buy |
|---|---|---|
Best Pick 1  | Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane Best for: Commercial buildings | Check Price |
Best Pick 2  | NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane Best for: High-demand settings | Check Price |
Best Pick 3  | Rheem 18kW 240V Tankless Electric Water Heater, Gray Best for: Electric installations | Check Price |
Best Pick 4  | Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY Best for: Residential use | Check Price |
Best Pick 5  | Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water Best for: Mid-sized homes | Check Price |
How We Picked
Through rigorous evaluation, we selected the best commercial tankless water heater models by prioritizing build quality, real-world performance, safety, and durability. We assessed standout features like indoor/outdoor versatility found in Rinnai’s CX199iN and RX199iN, and precise temperature control on Rheem’s electric options. We ruled out units with insufficient flow rates for commercial demand.
Condensing technology, such as in the Rinnai CU160iN, was favored for energy efficiency. Performance metrics like GPM and BTU output were crucial for determining suitability for diverse commercial needs.
What Most Buyers Get Wrong
Commercial Flow Rate Demands
Commercial settings often demand simultaneous hot water use from multiple fixtures. Look beyond simple GPM ratings and consider the maximum flow rate at your required temperature rise. For example, the Rheem RTGH Series offers up to 8.4 GPM, indicating it can handle higher simultaneous demands compared to models rated around 7.0 GPM like the Rheem RTG-70DVLN-3 series.
Matching your peak usage to the unit’s capacity is crucial to avoid customer complaints due to lukewarm water.
Condensing vs. Non-Condensing Efficiency
Commercial tankless water heaters come in condensing and non-condensing types, significantly impacting energy efficiency and operating costs. Condensing models, such as the Rinnai CX199iN and Rinnai CU160iN, capture extra heat from exhaust gases, leading to higher efficiency (often 90% or more). Non-condensing models, like the Rheem RTG-70DVLN-3 series, are typically less efficient but often have a lower upfront cost.
For high-volume commercial use, the long-term energy savings of a condensing unit usually justify the initial investment.
1. Rinnai CX199iN Condensing Smart Sense Commercial Natural Gas or Propane
Best for: Commercial installations needing flexible fuel.
Boasting a thermal efficiency rating of 97%, this Rinnai tankless water heater minimizes energy use, directly reducing operational costs for your business. Its Smart Sense gas control system allows for seamless switching between natural gas and propane, offering unparalleled fuel flexibility.
With a maximum flow rate of 11.1 GPM, this unit can support multiple fixtures simultaneously, preventing cold water interruptions during peak demand. Installation flexibility is enhanced as it can be positioned indoors or outdoors with the appropriate venting kit.
Pros
- 97% thermal efficiency for reduced energy bills.
- Smart Sense gas control for propane/natural gas use.
- 11.1 GPM flow rate for high demand.
- Indoor/outdoor installation compatibility.
Cons
- RX-OVC vent cap required for outdoor installations.
This Rinnai condensing unit is ideal for businesses needing consistent hot water with flexible fuel options. Its high efficiency makes it a cost-effective choice for commercial settings.
2. NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane
Best for: Compact businesses needing high flow.
This Rinnai condensing tankless water heater offers up to 11.1 GPM, enough to run 7 fixtures at once, despite its compact, suitcase-sized footprint. Its Smart Sense gas control system ensures efficient operation whether you use propane or natural gas.
The unit’s Versa Vent system provides extensive installation flexibility, allowing placement indoors or outdoors. With a heat output of 199,000 BTU and an efficiency rating of .98 UEF, it reliably delivers hot water while minimizing energy waste.
Pros
- Up to 11.1 GPM for multi-fixture use.
- Compact design saves valuable space.
- Smart Sense system for fuel flexibility.
- High .98 UEF efficiency rating.
Cons
- Maximum temperature is limited to 140 degrees Fahrenheit.
Ideal for businesses that require significant hot water capacity but have limited installation space. This Rinnai model provides powerful performance in a small package.
3. Rheem 18kW 240V Tankless Electric Water Heater, Gray
Best for: High-demand electric water heating.
Featuring a robust 18,000-watt heating element, this Rheem electric tankless water heater delivers up to 4.4 GPM, ensuring rapid hot water delivery for commercial applications. Its advanced self-modulation technology precisely matches power output to your specific hot water demand.
The durable copper immersion heating elements are field serviceable, extending the unit’s lifespan. An external digital thermostatic control with an LED display offers precise temperature adjustments in 1-degree increments for consistent comfort.
Pros
- 18kW wattage for strong heating power.
- 4.4 GPM flow rate for commercial use.
- Durable copper heating elements.
- Precise digital temperature control.
Cons
- Requires a 240V electrical connection.
This Rheem electric heater is a powerful solution for businesses needing consistent, on-demand hot water. Its precise temperature control and durable components suit demanding commercial environments.
4. Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
Best for: Medium-demand electric water use.
With 13kW of power, this Rheem electric tankless water heater provides up to 4.8 GPM, efficiently meeting the hot water needs of various commercial settings. Its 99.8% energy efficiency ensures minimal waste and lower operational costs.
The unit’s external digital control allows for precise temperature adjustment in 1-degree increments, ensuring you get the exact temperature needed. Self-modulating power control means it only uses the energy required for the current demand.
Pros
- 13kW heating capacity.
- Up to 4.8 GPM flow rate.
- 99.8% energy efficiency.
- Precise 1°F temperature adjustment.
Cons
- Flow rate may be insufficient for very high simultaneous demand.
This Rheem electric tankless water heater is suitable for businesses requiring a steady supply of hot water with efficient energy usage. Its adjustable temperature is perfect for varied commercial needs.
5. Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water
Best for: Mid-capacity natural gas hot water.
Delivering up to 7.0 GPM, this Rheem natural gas tankless water heater is ideal for 2-3 bathroom commercial spaces, powerfully supporting simultaneous uses like showers and laundry. Its 160,000 BTU output ensures rapid, reliable hot water even during peak demand.
Designed for indoor installation, this unit boasts a durable, compact metal cabinet and supports easy wall mounting. Hot-start programming helps to minimize cold water bursts, providing a more consistent hot water experience.
Pros
- 7.0 GPM flow rate for multi-fixture use.
- 160,000 BTU heat output.
- Durable indoor metal cabinet.
- Hot-start programming for consistency.
Cons
- Not compatible with smart home systems.
This Rheem natural gas water heater is a reliable choice for businesses needing a consistent supply of hot water for multiple applications. Its indoor design and robust performance suit busy commercial environments.
6. Westinghouse Tankless Water Heater Electric 14kW 240V, Instant On-Demand Hot
Best for: Small commercial electric hot water.
This Westinghouse electric tankless water heater offers instant, on-demand hot water with a maximum flow rate of 3.38 GPM and a starting flow rate as low as 0.5 GPM. Its 14kW heating system ensures it’s ready when you need it.
Requiring hard wiring, this unit operates at 240V and is compatible with Google Assistant, Alexa, and Wi-Fi for smart home integration. The bottom 1/2-inch NPT water connection simplifies installation.
Pros
- 3.38 GPM maximum flow rate.
- 0.5 GPM minimum starting flow rate.
- Smart home compatible.
- 14kW heating power.
Cons
- Requires a dedicated 60-amp circuit breaker and 6 AWG wire.
This Westinghouse electric tankless water heater is an efficient solution for smaller commercial spaces or specific point-of-use needs where instant hot water is essential. Its smart features offer modern convenience.
7. Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water
Best for: Outdoor liquid propane water heating.
Designed for outdoor installation, this Rheem liquid propane tankless water heater provides up to 7.0 GPM, perfect for applications needing to serve 2-3 bathrooms simultaneously. Powered by 180,000 BTUs, it ensures fast, reliable hot water flow.
This unit features a durable metal cabinet built to withstand outdoor conditions and supports easy wall mounting. Its compact and lightweight design aids in installation, and 1/2 gas line compatibility simplifies connection.
Pros
- 7.0 GPM flow rate for multiple fixtures.
- 180,000 BTU heat output.
- Outdoor rated durable cabinet.
- Compact and lightweight design.
Cons
- Propane fuel source required, may not be suitable for all locations.
This Rheem liquid propane water heater is an excellent option for outdoor commercial installations requiring a robust supply of hot water. Its design prioritizes durability and ease of use.
8. Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater, Indoor
Best for: Commercial indoor gas heating.
With a high-performance 9 GPM hot water flow rate, this Rinnai CU160iN commercial tankless water heater delivers a powerful, constant stream essential for business operations. Its space-saving design conserves energy by heating only when necessary.
This unit features Wi-Fi monitoring capabilities and Circ-Logic technology for optimized recirculation, ensuring hot water is ready when needed. Multiple venting options enhance installation flexibility for various commercial spaces.
Pros
- 9 GPM flow rate for demanding use.
- Energy-saving on-demand heating.
- Wi-Fi monitoring included.
- Circ-Logic recirculation technology.
Cons
- Specific efficiency rating not provided in details.
This Rinnai commercial gas water heater is perfect for businesses that require a high and consistent flow rate of hot water. Its smart features and energy efficiency make it a practical choice for commercial settings.
9. Rheem RTG-70XLN-3 High Efficiency Non-Condensing Outdoor Tankless Natural Gas Water
Best for: Outdoor natural gas for mid-volume.
This Rheem RTG-70XLN-3 outdoor tankless natural gas water heater provides up to 7.0 GPM, ideal for properties that need hot water for 2-3 bathrooms concurrently. It operates with 160,000 BTUs for quick and dependable hot water delivery.
Featuring freeze protection, this unit is robust for outdoor installations. Its self-diagnostic program and digital display simplify operation and maintenance, while the low activation flow rate ensures it engages even with minimal water use.
Pros
- 7.0 GPM flow rate for multiple fixtures.
- 160,000 BTU heat output.
- Outdoor installation with freeze protection.
- Self-diagnostic program for reliability.
Cons
- Requires a natural gas connection.
This Rheem tankless water heater is designed for outdoor installation, offering reliable natural gas hot water for mid-sized commercial applications. Its robust features ensure consistent performance in various conditions.
10. Rheem RRTGH84DVLN3701171 Rheem RTGH Series 8.4 GPM 157,000 BTU 120
Best for: Versatile gas water heating.
With a flow rate ranging from 0.4 to 8.4 GPM, this Rheem RTGH Series water heater dynamically adjusts to meet your specific hot water needs, from light use to simultaneous demands. Electric ignition ensures reliable operation.
The unit offers adjustable temperature settings from 100 to 140°F, with a default of 120°F, providing precise control over your hot water. It features exclusive Hot Start programming and an Overheat Film Wrap for enhanced safety and performance.
Pros
- 0.4 to 8.4 GPM adjustable flow.
- 100-140°F temperature range.
- Hot Start Programming for consistency.
- Overheat Film Wrap for safety.
Cons
- Warranty covers 1 year labor, 15 year heat exchanger, and 5 year parts.
This Rheem RTGH series water heater is suitable for diverse commercial needs requiring variable flow rates and precise temperature control. Its specialized features ensure efficient and safe operation.
Gas vs. Electric Performance for Tankless Heater Loads
The single most critical factor when selecting a best commercial tankless water heater is fuel source, and specifically, the BTU output for gas models versus kW for electric. This is not a minor detail to be glossed over; it dictates the practical upper limits of simultaneous hot water delivery. Gas units, such as the Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater or the Rheem RTG-70DVLN-3 High Efficiency Non-Condensing Indoor Tankless Natural Gas Water, boast BTU ratings like 160,000 BTU, which directly translate to higher flow rates per minute (GPM) before the water temperature drops significantly.
These higher BTU units are inherently better suited for high-demand applications where multiple fixtures might be running simultaneously – think busy restaurant kitchens or multi-head shower facilities.
Electric units, though often simpler in installation and quieter, face a fundamental capacity limitation directly tied to their power draw. The Rheem 18kW 240V Tankless Electric Water Heater, for instance, is powerful for an electric model, but its 18kW rating will struggle to keep pace with the sustained simultaneous demand that a 160,000 BTU gas unit can handle. The Westinghouse Tankless Water Heater Electric 14kW 240V, with its lower kW rating, is even more restricted, suited primarily for single-point-of-use applications or very light residential demand.
Attempting to push an electric unit past its rated capacity results in tepid water and frustration, a trade-off that gas units with their substantially higher energy inputs largely avoid.
Beyond raw heating capacity, the specific design nuances matter. Rinnai offers models like the CX199iN Condensing Smart Sense Commercial Natural Gas or Propane and the slightly updated NEW Rinnai RX199iN Condensing Smart Sense Natural Gas or Propane, which focus on versatility with features like Versa Vent for indoor/outdoor installation and Smart Sense gas control for fuel flexibility. This adaptability, coupled with condensing technology for enhanced efficiency, differentiates them from non-condensing gas units like the Rheem RTG-70DVLN-3.
Similarly, Rheem’s electric offerings, like the RTEX-13 Residential Tankless Water Heater, emphasize precise digital thermostatic control and self-modulation, aiming for granular temperature accuracy which is less of a priority for high-volume gas heating applications where raw output speed is paramount.
Therefore, while electric tankless water heaters offer benefits in terms of installation simplicity and precise temperature modulation for single or low-demand uses, any commercial scenario or even a high-demand household should prioritize gas units with sufficient BTU output. The Rheem RTG-70XLP-3 High Efficiency Non-Condensing Outdoor Tankless Liquid Propane Water, for example, clearly signals its intended load capacity with its 160,000 BTU rating, making it far more suitable for substantial hot water needs than, say, the 14kW Westinghouse electric model. Matching the fuel source’s inherent energy density to your actual hot water usage is the non-negotiable step.
For facilities demanding robust hot water performance without compromise, the Rinnai CU160iN Commercial Natural Gas Condensing Tankless Water Heater stands out due to its combination of high heating capacity and condensing efficiency.
What to Look for in a Commercial Tankless Water Heater
Flow rate capacity
For commercial applications, selecting the correct flow rate is paramount. Business needs vary; a small office might require 6-10 GPM to handle sinks and basic appliances, while a busy restaurant kitchen demanding multiple dishwashers and sinks simultaneously needs 25 GPM or more. Always calculate your peak demand by summing the GPM of all fixtures likely to run at once.
Opt for units explicitly rated for your maximum simultaneous usage to avoid lukewarm water during busy periods. Prioritize heaters with higher GPM ratings if there’s any doubt about your peak load; a slightly oversized unit is preferable to an undersized one.
Energy efficiency ratings
When evaluating energy efficiency, focus on models with high Energy Factor (EF) ratings. These indicate minimal standby energy loss, meaning less wasted heat. Natural gas and propane models generally offer faster heat recovery and higher GPM than electric units of comparable size, making them suitable for high-demand businesses.
Electric units, however, can be more efficient in terms of standby loss and offer simpler installation without venting. For consistent, high-volume hot water, natural gas or propane with an EF of 0.90 or higher is the optimal choice for most commercial settings.
Temperature control precision
Precise temperature control is crucial for comfort and safety. Look for digital temperature controllers that allow for exact Fahrenheit settings, unlike older analog dials. These digital systems maintain a consistent output temperature even as incoming water temperature or demand fluctuates, preventing scalding or insufficient heat.
Advanced models also feature an antiscald protection that adjusts the flow to prevent dangerous temperature spikes. For businesses with public access or where precise temperatures are critical, digital controllers with built-in safety mechanisms are the clear choice.
Unit dimensions and installation space
Consider the physical footprint and installation requirements of the unit. Compact, wall-mounted units are ideal for businesses with limited floor space, efficiently utilizing vertical clearance. Floorstanding models offer greater capacity and are often easier to service in larger facilities.
Always check venting requirements; gas units need adequate exhaust ventilation and proper clearances from combustible materials, while electric units require sufficient electrical supply. For space-constrained environments, prioritize compact, wall-mounted gas units to maximize your operational area.
Which Should You Choose?
- If you need maximum flexibility for installation location and fuel type, look for a model with indoor/outdoor venting and a Smart Sense gas control system that accommodates both natural gas and propane.
- If you have a 2-3 bathroom home with multiple simultaneous hot water needs, choose a high-efficiency model that delivers at least 7.0 GPM and is powered by natural gas or liquid propane.
- If you require precise temperature control and efficiency for a smaller application, consider an electric model with external digital thermostatic control and self-modulating power adjustment.
- If you are installing indoors and want energy and space efficiency with multiple venting choices, opt for a condensing tankless water heater designed for commercial use.
Quick Best Commercial Tankless Water Heater Buying Checklist
- Assess Your Business’s Peak Demand: Calculate the maximum simultaneous hot water needs to determine the required GPM.
- Prioritize Energy Efficiency: Look for high Energy Factor (EF) ratings to minimize operating costs over time.
- Choose the Right Fuel Type: Natural gas, propane, or electric options have different installation and operational considerations.
- Verify Temperature Accuracy: Ensure the unit can maintain a consistent output temperature, essential for many business applications.
- Consider Space and Venting: Measure available installation space and understand the venting requirements for your chosen model.
- Check Warranty and Support: Investigate the manufacturer’s warranty and the availability of replacement parts and service.
Frequently Asked Questions
What Is The Primary Benefit Of A Commercial Tankless Water Heater?
The primary benefit of a commercial tankless water heater is on-demand hot water, meaning it heats water only when needed. This significantly reduces energy waste compared to traditional tank heaters, leading to lower utility bills and a more sustainable operation for your business.
How Do I Determine The Right Flow Rate (Gpm) For My Business?
To determine the right flow rate, calculate the maximum number of hot water fixtures or appliances that might run simultaneously. Summing their individual GPM requirements will give you the necessary total GPM for your commercial tankless water heater.
Are Commercial Tankless Water Heaters More Energy-Efficient Than Tank Models?
Yes, commercial tankless water heaters are generally far more energy-efficient than traditional tank models because they only heat water as needed. This ‘on-demand’ heating eliminates the standby energy losses associated with keeping a large tank of water hot 24/7.
What Maintenance Is Typically Required For These Units?
Routine maintenance for commercial tankless water heaters often involves descaling to prevent mineral buildup, especially in hard water areas. Annual inspections of the venting and gas connections are also crucial for safety and optimal performance.
Can A Commercial Tankless Water Heater Handle Multiple Hot Water Demands At Once?
Yes, a properly sized commercial tankless water heater can handle multiple simultaneous hot water demands. Modern units are designed with high flow rates, ensuring that appliances and fixtures receive sufficient hot water even when used concurrently.
Final Words
Investing in the best commercial tankless water heater provides a reliable, efficient, and cost-effective solution for your business’s hot water needs. Its on-demand heating capability ensures ample hot water while significantly cutting down on energy consumption. Upgrade your business’s infrastructure today for long-term savings and enhanced performance.