Best commercial tankless water heater

7 Best Commercial Tankless Water Heater 2023+Buying Guide

Are you looking for the best-rated commercial tankless water heater for your hotel, restaurant, salon, spa, laundromat, or anything in between? We have got you covered, keep reading. 

I have installed tankless water heaters at many commercial places like Walmart and laundromats and I know the things you expect from a heater are robust, efficient, high hot water supply, and a temperature rise of upto 185°F.

For this commercial tankless water heater review, we have tested over 17 models, studied design, hardware, and customer feedback, and curated what truly can be called the best. At the end of this review, we have also included a brief buying guide to help you understand what to look for in a water heater when you are out shopping for one. 

Enough said; let’s jump straight to reviews now. 

REVIEWS: Best commercial tankless water heater

1. Rinnai RL94IN

Rinnai commercial tankless water heater for restaurant

Rinnai RL94IN
  • Activation flow: 0.4 GPM
  • Max flow: 9.8 GPM
  • Fuel: Natural gas
  • Capacity: 199,000 BTU
  • Max temperature: 140°F

The first in our list of the best commercial tankless water heaters is from Rinnai. This RL94IN is a natural gas-fired tankless unit with an input heating capacity of upto 199K BTUs. It can shell out a max of 9.8 GPM hot water in warm southern regions, implying that this single unit can serve more than 4-5 showers at a time. With a maximum heating temperature of upto 140°F, this model is ideal for hotel and guesthouse bathrooms. You can install multiple units in an array and conveniently control it via a commercial controller which of course you will have to buy separately. 

Rinnai RL94IN features advanced circ-logic technology, meaning it has a built-in recirculation loop to prevent surprise cold water bursts. Another noteworthy feature is the wifi monitoring which helps you stay aware of system health and scale build-up.


  • Circ-logic tech with recirculation inbuildnFast hot water deliverynMultiple units can be installed in an array in a commercial facilitynComes with a year of the commercial warrantynWifi monitoringnPerfect for small hotels, guesthouses, and restaurantn
  • The maximum temperature that can be reached is not more than 140°Fn

2. Rinnai CU199iN

Rinnai CU199iN
  • Activation flow: 0.4 GPM
  • Max flow: 11 GPM
  • Temperature: Max 185°F
  • Type: Condensing
  • Capacity: 199,000 BTUs

Rinnai is so prevalent in the commercial tankless water heater segment that we couldn’t help ourselves from mentioning another model. 

The unit in discussion is Rinnai CU199iN. This natural gas-fired unit can render upto 11 GPM of hot water at a maximum of 185°F temperature, which is required in commercial settings.

The best part? This model is a condensing unit, which means more efficiency at 97% and more savings. It’s also Energy Star certified. Another thing about this model for being a condensing model is that you can install that cheap PVC vent system. It has minimal greenhouse footprints with ultra-low NOx output. Sure this unit is slightly expensive, but it pays for it in the long run. 

Similar to the earlier model we discussed, Rinnai CU199iN equips circ-logic technology and is WiFi-ready. And finally, it brings you up to 8 years of commercial warranty on the heat exchanger. 

  • Upto 185°F temperature rise useful for commercial usenHighly efficient and energy star certified modelnRequires cheaper venting systemnUpto 11 GPM hot water flown
  • Slightly expensive unit. n

3. Noritz NC380

commercial tankless water heater for laundromat

Noritz NC380
  • Activation flow: 0.5 GPM
  • Maximum flow: 13.2 GPM
  • Fuel: Natural gas/LP
  • Max temperature: 180°F
  • Capacity: 380,000 BTU

This is a high-capacity gas-fired tankless water heater we are dealing with here. The Noritz NC380 is a special-grade, commercial tankless water heater designed for large commercial places. You can hook up a rack system and install upto a 24-unit array of this model and have access to up to 9.1 million BTUs of heating capacity. The single unit can take heat input of as much as 380,000 BTUs and render out 13.2 GPM of hot water at Max 180°F. 

Noritz commercial features a 25% thicker copper heat exchanger than the standard model, giving it more sturdiness. 

As you may already be aware, for above 200k BTUs, a special plumbing license also called a boiler operator license, will be required. 

That said, both natural gas and liquid propane options are available. Being a non-condensing model, the Noritz NC380 requires an expensive venting system and has average thermal efficiency. The unit offers a 0.84 energy factor which means it wastes 16 % of the energy consumed. You can install this model either indoors or outdoors. 

  • A high-performance model with a large heating capacitynIdeal for large commercial placesnUpto 180°F water heatingnBuilt to last with robust designnCSA certifiedn
  • Average energy efficiencyn

4. Rheem RTGH commercial

commercial water heater for hotels

  • Activation flow: 0.4 GPM
  • Max flow: 9.5 GPM
  • Max temperature: 185°F
  • Fuel: Natural gas/ liquid propane
  • Type: Condensing
  • Capacity: 199,000 BTUs

This is the second condensing model in this list after Rinnai, but it’s cheaper and just as energy efficient. The Rheem RTGH is a commercial tankless water heater with a heating capacity of upto 199,000 BTUs. It can deliver up to 9.5 GPM of hot water at 185°F temperature. The default temperature range is under 120°F, and you will need a commercial remote to raise the bar. 

The unit boasts ultra-low NOx output, and it follows California environmental regulations. Rheem RTGH series is up to 96% energy efficient and one of the best for commercial locations like hotels, restaurants, and industrial applications. 

You can up the hot water output by quickly installing multiple units in line and solving your and your customer’s hot water needs. 

Another feature I would like you to know is the scale buildup alert. It gives an alert error code when descaling is required. Here’s the guide for that.

  • Highly energy efficientnCheaper schedule 40 PVC venting can be usednIdeal for medium-sized commercial locationsn
  • None foundn

5. Stiebel Eltron Tempra 36 kW

Commercial electric tankless water heater

Stiebel Eltron Tempra 36 kW
  • Power: 32kW, 240 volts
  • Activation flow: 0.7 GPM
  • Maximum flow: 7 GPM
  • Max temperature: 140°F
  • Service: 300 Amp
  • Breaker req: 3x 50Amp double pole breaker

If you want to break free from the headache of venting and all that stuff, then an electric tankless water heater is the best option. 

Undoubtedly the most powerful in the electric segment, the Tempra 36 from Stiebel Eltron delivers 36k watts of heat. It’s more efficient than gas-fired models. 

The tankless model can deliver up to 7.5 GPM of hot water and is ideal for small commercial settings and those with space issues. It’s perfect for small laundromats barbershops, salons, and spas. 

Tempra equips a triple copper heat exchanger, a convenient temperature control knob, and upto 7 years of warranty on leakage. The operation of the electric model is completely silent. 

Sure this model saves money on energy, and the unit itself is cheaper, but upgrading your service to 300Amps could get expensive quickly.

  • No venting is required so saves money on that and spacenComplete noise-free operationnIdeal for small commercial places. n
  • Service upgrade could get expensivenHeats water slower than gas-fired unitsnNot ideal for cold climatesn

6. Rheem RTEH65 commercial

Rheem RTEH65 commercial
  • Power: 6.5kW, 240volt
  • Activation flow: 0.25 GPM
  • Max flow: 1 GPM
  • Service req: 100 amps
  • Breaker: 1x30Amp double pole
  • Max temperature: 140°F

This is another electric tankless water heater on this list, but it’s a smaller model this time. The Rheem RTEH65 is a mini tankless unit designed for lavatory sink usage. It’s a commercial model, perfect for office washrooms, salons, and doctors’ offices. 

It has a low activation rate of just 0.25 GPM and draws quick hot water. Depending on the temperature of cold water, you can get hot water at up to a 1GPM rate. Rheem RTEH series is non-thermostatic, which means you can’t set the hot water temperature and water coming out will be preset to a maximum of 140°F.

Speaking of electrical requirements, the unit is not much of a burden for your service panel. It only draws a maximum of 27 Amps, and a 100Amp service panel is more than enough. You will also require a single 30Amp double pole breaker. 

  • Ideal for small commercial establishmentsnEasy to install and fast operationnSpace-saving and compactn
  • Not for a large establishmentnNot ideal for cold climates. n

7. Stiebel Eltron DHC 10-2

  • Power: 9.6 kW, 240volt
  • Activation flow: 0.7 GPM
  • Max flow: 1.37 GPM
  • Max temperature: 120°F
  • Breaker: 40 Amp double pole
  • Service req: 100 Amps

Another installment from German Stiebel Eltron, the DHC 10-2, is a perfect solution for commercial settings like gas stations, restaurant kitchens, warehouses, offices, and similar locations where hot water supply to the sink is needed. 

With upto 1.37 GPM of hot water flow in warm climates, it can render hot water to two lavatory sinks or a single kitchen sink.

Speaking of construction, the water heater is equipped with a robust copper heat exchanger and a hydraulically controlled flow switch. DHC 10-2 offers silent operation. 

On the downside, the unit has preset temperature settings up to 120°F that can’t be changed. When the climate is warm, it delivers 120°F hot water and is warm in an otherwise situation. 

  • Highly energy efficientnIdeal for commercial lavatoriesnCan deliver hot water to upto two sinks or a single kitchen sinkn
  • No temperature adjustmentnMax temperature is just 120°Fn

If you need a water heater for single handwash fixtures, check out our review of 110/120-volt tankless water heaters.

Commercial tankless water heater buying guide: What to look for

buying guide Best 110-Volt Tankless Water Heater

Commercial tankless water heaters are usually slightly different than their residential counterparts in capacity and other parameters. Let’s go through what you should look for in one. 

Hot water flow or size

I have gone into detail about sizing tankless water heaters in the article here, but I’ll give a briefing. The sizing we are referring to here is the maximum hot water a tankless water heater can deliver. It’s measured in GPM or gallon per minute. The biggest size in this list is the 13.2 GPM from Noritz. But remember, the colder the incoming water that needs to be heated the lower the flow rate of the same tankless unit will be. All manufacturer provides this data. 

Okay, so to size the tankless unit or to determine how many units u need to install in case of large commercial settings like hotels or laundromats, calculate the GPM of all the fixtures that can be at the same time and decide accordingly which unit will be sufficient for you or how many you will need. 

For instance, say you have a small motel with 10 bathrooms. Say all 10 showers with 1.5 GPM each are used in the morning. Then that will be the 15 GPM water heater you will need. Either install a single big one or multiple small units in line. You should also consult a contractor for this. 

Fuel/ power source

Tankless water heaters are either gas or electric. Gas-fired heaters heat water faster but are expensive and require venting and stuff but are still viable options than electric ones unless you have small commercial facilities like salons, restaurants, spas, etc. Learn more about gas vs electric tankless water heaters here.

Electric models need expensive service upgrades, which can get expensive and can’t deliver as much hot water as gas units. 


Commercial tankless units can heat water to 185°F, which is required for commercial settings like manufacturing facilities. However, most tankless units require a commercial remote to raise the temperature. Make sure the model you are selecting provides these things. 


It’s no surprise. Commercial heating units are expensive, and so are the repairs and replacements. So make sure the model you are selecting provides a sufficient commercial warranty.

For the best whole-house residential tankless water heater, click here.

Popular questions related to commercial tankless water heater

Are tankless water heaters suitable for commercial use?

Yes, if appropriately sized, next-generation tankless water heaters can provide unlimited hot water that you never run out of. Plus it saves 30% more energy than traditional tank models and 90% space savings. Another thing is that if they are correctly maintained, they can last twice as much as their tank counterparts. 

How long does a commercial tankless water heater last?

A commercial tankless water heater on maintaining and flushing regularly can provide you service for up to 20 years. 

Which tankless water heater is the best?

From a commercial point of view, Rinnai, Noritz, and Rheem are all excellent options. 

What is the highest GPM tankless water heater?

Right now, the highest GPM commercial tankless water heater in stock is Nortiz which is already listed above. It delivers up to 13.2 GPM of hot water. 

How much is a commercial tankless water heater? 

Depending on your chosen size and brand, a commercial tankless water heater can cost between $1000 to $4000.

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