Tankless water heaters are an efficient and cost-effective replacement for storage tank water heaters. Like your standard geyser, tankless water heaters can be powered by either propane or electricity. But, what are the best gas tankless water heaters out there?
Gas tankless water heaters (GTWH) heat water using a pilot flame. When you turn on your faucet, water enters the heater and flows through a copper coil. The pilot heats the coil, heating the water.
GTWHs are more efficient than their electric cousins, reaching energy efficiency ratings of 9.5 or higher. However, choosing the best gas tankless water heater can be overwhelming, especially if this is your first time purchasing one. So, to make things easier, we’ve curated a list of the best gas tankless water heaters to buy in 2022.
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Table of Contents
Best Gas Tankless Water Heaters – Climatebiz Picks
- Rheem Professional Prestige Series (Best Sustainable Option)
- Takagi T-H3-DV-N (Best Indoor)
- Rinnai RU SENSEI™ RU199eP (Best Outdoor)
- Noritz EZ Series (EZ111/EZ98) (Best Warranty)
How To Choose The Best Gas Tankless Water Heater
Here are several factors to consider when choosing the best gas tankless water heater for your home:
- Types Of Gas Tankless Water Heaters
- The Rate Of Flow (GPM)
- Temperature Rise
- Efficiency
Types of Gas Tankless Water Heaters
You need to consider the physical size of your GTWH. Do you want to install a POU (point of use) or a whole-house system? A POU system will use less gas and produce hot water at a lower flow rate. A whole-house system will use more gas and deliver water at a much higher flow rate.
There are two main types of gas tankless water heaters:
- Point Of Use
- Whole-Home
Point Of Use Gas Tankless Water Heaters
A point-of-use system, also known as a single point unit, can either be installed at each plumbing point or in series if you need a more significant flow rate with a higher temperature rise.
The average flow rate for a POU system is between 1.5 and 3 gallons per minute. Therefore, single-point systems are the best gas tankless water heaters for new homes or guest flats.
Whole-house Gas Tankless Water Heaters
A whole-home system involves water flowing through one large GTWH, supplying your entire plumbing system. These are the best gas tankless water heaters for existing homes as they can replace your current geyser.
The average flow rate for a whole-house system is between 6 and 10 gallons per minute. So they’ll produce enough hot water for at least two showers and a sink running simultaneously.
Whole-home systems are larger — you won’t be able to hide one under your kitchen sink. You’ll typically install one in your garage or outside. If you’re replacing your geyser, you can install it in the same spot.
Gas Tankless Water Heater Flow Rate
The flow rate of your GTWH determines how much water it can heat to the desired temperature; this rate is measured in gallons per minute and determines which gas tankless water heater is best for your home.
Each hot water fixture in your house has a different flow rate. For example, a shower requires 2 GPM (gallons per minute) while a bath requires 4 GPM.
To determine your overall flow rate, you’ll need to add up the GPM of your hot water fixtures. You probably won’t be using all the appliances simultaneously — choosing regular fixtures will give an accurate GPM.
For example, it’s most likely that a household of four will only run two showers and two sinks simultaneously.
Let’s walk through it.
Average GPM of Hot Water Fixtures
Below we’ve included a table of the average GPM for hot water fixtures.
| Fixture | GPM |
|---|---|
| Showers | 2 |
| Baths | 4 |
| Kitchen Sinks | 2 |
| Bathroom Sinks | 1.5 |
Here are things to consider:
- Sinks or shower heads with aerators have lower flow rates.
- Sometimes dishwashers or washing machines require a hot water inlet.
- Be sure to include a utility sink if you use one.
- Include guest houses or garden cottages unless you plan to put them on a different system.
Calculating Your Required GPM
This step is easy; you just need to add up the flow rates of fixtures you’d use simultaneously.
Here are a couple of examples:
- If you use two showers – 4 GPM
- Two showers and a sink – 1.5 GPM
- Two showers, a bath, and a sink – 9.5 GPM
The Temperature Rise
Finally, you’ll need to consider the temperature rise your gas electric water heater will need to handle. The temperature rise is the difference between outlet and inlet temperature; this is the value your GTWH will need to heat the water by (per minute).
Different climates have different temperature rises. For example, a hot climate will have a higher inlet temperature of up to 62ºF. That means that the water only needs to rise by 58ºF at most. However, the average water inlet temperature is around 40ºF. You can use the image below to determine your area’s inlet water temperature.
Source: phcppros
According to the U.S. Consumer Product Safety Commission, your water temperature should be between 104ºF and 120ºF.
If the average inlet temperature is 40ºF, and the outlet needs to be 120ºF, that’s an 80ºF temperature rise.
British Thermal Units
A British thermal unit, or Btu, is a measurement of heat. Its the amount of heat required to raise the temperature of a pound of water by 1ºF. Often, gas tankless water heaters have a Btu rating, which tells you how hot the heater can get. The higher the Btu rating, the higher the GPM.
To calculate the required Btu, you can use the following formula. While it’s not necessary to buy a GTWH, it’s interesting to know.
Btu = GPM x ∆t x 500
GPM – Flow rate in gallons per minute
∆t – Temperature rise required
500 – The Btu multiplier is 8.66 pounds of water (1 gallon) x 60 minutes.
It’s also interesting to note that Btu is used to measure heat transfer in a room. So, for example, air heat exchangers also have a Btu rating. And if you think about it, tankless water heaters are a type of heat exchanger.
Efficiency
Lastly, the efficiency of the gas tankless water heater is something to consider. The efficiency is rated between 0 – 1. However, no heater will be 100% efficient, and the best gas tankless water heaters have a rating of around 0.93.
Efficiency is measured using the energy factor (EF). It’s a standard that shows a heat loss ratio to fuel used. For example, most tankless water heaters have an EF rating of 0.8 – 0.9.
The average universal energy factor of our best gas tankless water heaters is 0.89.
11 Best Gas Tankless Water Heaters
Without further delay, here’s our list of the top 11 best gas tankless water heaters, according to our experts.
01. Rinnai RU SENSEI™ RU199eP
Promising double the lifespan of a regular GTWH, the Rinnai RU SENSEI™ RU199eP had to be on this list. The compact design allows you to install this gas tankless water heater almost anywhere.
The only real limitation with the RU199eP is that you can only install it outdoors. So, if you have an apartment, this GTWH isn’t for you.
However, the RU199eP offers up to 199,000 Btu if you own a home. That’s more than enough for a whopping 11 GPM flow rate. It includes a mobile app to measure and control your water temperature from anywhere.
It also includes high-quality isolation and PRV valves inside the package – an extra savings bonus.
Dimensions
| Height | 26.4 Inches |
| Width | 18.5 Inches |
| Depth | 11.5 Inches |
| Gas Connection | 1/2 Inch |
| Weight | 64 lbs |
Specifications
| Fuel Type | Propane |
| UEF | 0.93 |
| Installation Type | Outdoor |
| Max Btu | 199,000 |
| Temp. Range | 98° F – 140° F |
| Min. Flow (GPM) | 0.26 |
| Max Flow (GPM) | 11 |
Warranty
It has a 15-year warranty on the heat exchanger, 5 years on parts, and 1 year on labor.
02. Rinnai V Series V94eP
Rinnai is one of the best gas tankless water heater manufacturers, so it’s no surprise that another model made our list.
The V Series V94eP is the perfect blend of efficiency, comfort, and durability — perfect for medium homes. It has a maximum flow rate of 9.8 GPM (three showers, and a kitchen sink).
The V94eP is also perfect for remodels, POU systems, and garden cottages. It’s a compact, easy-to-install design with a warranty you can’t ignore.
However, it’s an outdoor-only GTWH, so you won’t be able to install it in your bathroom or kitchen.
Dimensions
| Height | 24.3 Inches |
| Width | 14.4 Inches |
| Depth | 9.6 Inches |
| Gas Connection | 1/2 Inches |
| Weight | 44.3 lbs |
Specifications
| Fuel Type | Propane |
| UEF | 0.81 |
| Installation Type | Outdoor |
| Max Btu | 199,000 |
| Temp. Range | 90ºF – 140ºF |
| Min. Flow (GPM) | 0.26 |
| Max Flow (GPM) | 9.8 |
Warranty
It has a 10-year warranty on the heat exchanger and a 5-year warranty for the parts. It also includes a 1-year reasonable labor warranty.
03. Noritz NRC66-DVNG
The Noritz NRC66-DVNG may not have all the bells and whistles, but it’s still a trust-worthy GTWH. Some highlights of this model include a temperature lockout and a high elevation adjustment.
While it doesn’t come with an app, it does have a built-in display window to ensure the pilot is working.
You can adjust the temperature to three preset outputs with an additional display. These are 120°F, 135°F, and 140°F.
It’s available as an outdoor or indoor gas tankless water heater and includes the additional required adapters for the vents.
Lastly, the NRC66-DVNG has a maximum flow rate of 6.6 GPM.
Dimensions
| Height | 23.6 Inches |
| Width | 13.8 Inches |
| Depth | 3.7 Inches |
| Gas Connection | 1/2 Inches |
| Weight | 44.3 lbs |
Specifications
| Fuel Type | Propane |
| UEF | 0.89 |
| Installation Type | Outdoor/Indoor |
| Max Btu | 120,000 |
| Rec. Wire Size (CU) | 100 – 140°F |
| Min. Flow (GPM) | 0.5 |
| Max Flow (GPM) | 6.6 |
Warranty
It has a 12-Year limited heat exchanger warranty, a 5-Year Limited parts warranty, and a 1-Year reasonable labor warranty.
04. Takagi T-H3-DV-N
This indoor gas tankless water heater can heat up to 199,000 Btu and around 10 gallons per minute.
The Takagi T-H3-DV-N is perfect for residential use — you can even attach it to your indoor heating systems. For example, you can use this GTWH for your radiators or underfloor heating.
While this model is for natural gas, Takagi has a propane option.
The primary heat exchanger utilizes copper alloy, which is 25 times more efficient than stainless steel. It’s also energy-star qualified with a 0.93 efficiency rating. You can link up to four units in series and up to 20 units with a multi-unit controller.
Not only does that make the T-H3-DV-N great for residential use, but also hostels or bed and breakfasts.
Dimensions
| Height | 22.50 Inches |
| Width | 17.75 Inches |
| Depth | 10.75 Inches |
| Gas Connection | 3/4 Inches |
| Weight | 59 lbs |
Specifications
| Fuel Type | Natural Gas |
| UEF | 0.93 |
| Installation Type | Indoor |
| Max Btu | 19,000 |
| Temp. Range | Up To 140ºF |
| Min. Flow (GPM) | 0.4 |
| Max Flow (GPM) | 10 |
Warranty
It has a 15-year warranty on the heat exchanger and a 5-year warranty on the parts. Unfortunately, it doesn’t include a labor warranty.
05. Am. Stan. TCWH-199S
Am. Stan stands for American Standard Water Heaters, and TCWH-199S is the model in our spotlight.
The 199S refers to its maximum capacity of 199,000 Btus. This indoor gas tankless water heater has a maximum flow rate of 11 GPM, which is perfect for larger households.
The TCWH-199S is designed for superior thermal transfer and resistance to scale formation.
It also has an energy efficiency rating of 0.93, which can massively decrease your operating costs.
Dimensions
| Height | 17.38 Inches |
| Width | 15.25 Inches |
| Depth | 13.13 Inches |
| Gas Connection | 3/4 Inches |
| Weight | 88 lbs |
Specifications
| Fuel Type | Propane/Natural |
| UEF | 0.93 |
| Installation Type | Indoor |
| Max Btu | 199,000 |
| Temp. Range | 95ºF – 140ºF |
| Min. Flow (GPM) | 0.5 |
| Max Flow (GPM) | 11 |
Warranty
It has a 12-year limited warranty that only applies to single-family residences. In addition, it has a 5-year warranty on parts. However, you’ll need to ensure it’s installed according to the manual.
06. Noritz EZ111 EZ Series
The Noritz EZ111 from the EZ series is one of the market’s best gas tankless water heaters. Its compact design hides an impressive flow rate of 11.1 GPM.
You can install this unit inside, preferably in a garage or storage room. Fortunately, you can also install it outdoors, and it has an optional vent cap.
The EZ111 has features that really make it stand out from the rest. These include a remote thermostat control that adjusts the output between 100ºF – 140ºF.
Additionally, you can install it in series, doubling the output water temperature.
Dimensions
| Height | 27.0 Inches |
| Width | 18.5 Inches |
| Depth | 14.1 Inches |
| Gas Connection | 1/2 Inches |
| Weight | 81 lbs |
Specifications
| Fuel Type | Propane/Natural |
| UEF | 0.95 |
| Installation Type | Indoor/Outdoor |
| Max Btu | 199,000 |
| Temp. Range | 100°F – 140°F |
| Min. Flow (GPM) | 0.5 |
| Max Flow (GPM) | 11.1 |
Warranty
The EZ111 has a 25-year limited heat exchange warranty and a 5-year parts warranty. Lastly, it includes a 1-year reasonable labor warranty.
07. Rheem Performance Plus® ECO200
The Performance range from Rheem offers an excellent performing GTWH for indoor installation. This specific model, the ECO200, can produce up to 11 GPM of hot water with 199,000 Btu.
Using the app, you can also program the activation time of the gas tankless water heater.
In addition, the ECO200 prevents water wastage by reducing the flow of cold water. Once the outlet temperature meets the set temperature, the flow rate returns to normal.
Lastly, the model comes with a preinstalled pump, which is handy for easy installation.
Dimensions
| Height | 25-5/8 Inches |
| Width | 13-7/8 Inches |
| Depth | 9-7/8 Inches |
| Gas Connection | 3/4 Inches |
| Weight | 17.4 lbs |
Specifications
| Fuel Type | 36 |
| UEF | 0.82 |
| Installation Type | Indoor |
| Max Btu | 199,900 |
| Temp. Range | 85° – 140° F |
| Min. Flow (GPM) | 0.4 |
| Max Flow (GPM) | 9.5 |
Warranty
Residential units have a 12-year warranty period for the heat exchange and 5 years warranty for parts.
08. Noritz EZ98 EZ Series
The EZ98 has a maximum of 9.8 GPM, making it the little brother to the Noritz EZ111.
While it can only reach 180,000 Btu per hour, it’s still an excellent option for your whole house.
Moreover, it’s a versatile model that you can install indoors or outdoors.
Like the EZ111, this model has a thermostat you can control via an app.
However, the EZ98 is a gas tankless water heater with only two preset temperatures — 100ºF and 140ºF.
Dimensions
| Height | 27.0 Inches |
| Width | 18.5 Inches |
| Depth | 14.1 Inches |
| Gas Connection | 1/2 Inches |
| Weight | 81 lbs |
Specifications
| Fuel Type | Propane/Natural |
| UEF | 0.95 |
| Installation Type | Indoor/Outdoor |
| Max Btu | 180,000 |
| Temp. Range | 100ºF – 140ºF |
| Min. Flow (GPM) | 0.5 |
| Max Flow (GPM) | 9.8 |
Warranty
The EZ98 has a 25-year warranty for the heat exchanger. It also has a 5-year warranty for the parts and a 1-year warranty for fair labor.
09. Rinnai RL75eP RL Model Series
The RL75eP is a high-efficiency, non-condensing gas tankless water heater no larger than a small suitcase.
It has a heating range of 10,300 Btu to 180,000 Btu and a flow rate of up to 7.5 GPM, which is perfect for medium-sized families.
The RL75eP is an outdoor-only GTWH but is designed to have double the lifespan of your average GPM. That means this robust and compact gas tankless water heater can last up to 40 years.
Dimensions
| Height | 24.3 Inches |
| Width | 14.04 Inches |
| Depth | 9.6 Inches |
| Gas Connection | 1/2 NPT |
| Weight | 43.6 lbs |
Specifications
| Fuel Type | Propane |
| UEF | 0.81 |
| Installation Type | Outdoor |
| Max Btu | 180,000 |
| Temp. Range | 98ºF – 140ºF |
| Min. Flow (GPM) | 0.26 |
| Max Flow (GPM) | 7.5 |
Warranty
It has a warranty period of 12 years and a 5-year warranty on parts. It also includes a 1-year warranty for labor.
10. Rheem Professional Prestige Series: 9.5 GPM Indoor Tankless
As the name suggests, this gas tankless water heater has a maximum flow rate of 9.5 GPM. It’s also an indoor tankless water heater, so make sure you have space in your garage, basement, or bathroom. The specific model we’re looking at is the RTGH-95DVLN-2 model.
The Professional Prestige series has some features that really stand out. It includes a minimum flow rate of 0.26 GPM and a recirculation pump kit. This kit provides hot water to your taps faster and saves up to 12,000 gallons of water per year.
Lastly, this GTWH stays in a ready-fire state, which prevents cold water bursts during back-to-back uses.
Dimensions
| Height | 27-1/2 Inches |
| Width | 18-1/2 Inches |
| Depth | 9-3/4 Inches |
| Gas Connection | 3/4 Inches |
| Weight | 82 lbs |
Specifications
| Fuel Type | Propane/Natural |
| UEF | 0.93 |
| Installation Type | Indoor |
| Max Btu | 199,900 |
| Temp. Range | 85ºF – 140ºF |
| Min. Flow (GPM) | 0.26 |
| Max Flow (GPM) | 9.5 |
Warranty
It includes a 12-year warranty on the heat exchanger, 5 years on parts, and a 1-year labor warranty.
11. Eccotemp L5
Last on our list is the portable Eccotemp L5, with a flow rate of 1.5 GPM, making this the best gas tankless water heater for camping or RVs. It uses a 20 lbs propane tank to heat enough water for a low-flow shower.
The Eccotemp can reach up to 120ºF and be set as low as 50ºF for hot summer days. It includes an ignition powered by 2 “D” cell batteries, making it great for off-grid showers.
The ideal pressure range for the L5 is 20 to 80 PSI for its 1.5 GPM flow.
Dimensions
| Height | 18 Inches |
| Width | 11.5 Inches |
| Depth | 5.25 Inches |
| Gas Connection | 1/2 NPT |
| Weight | 11.2 lbs |
Specifications
| Fuel Type | Propane |
| UEF | – |
| Installation Type | Outdoor |
| Max Btu | 37,500 |
| Temp. Range | 50ºF – 120ºF |
| Min. Flow (GPM) | 0.5 |
| Max Flow (GPM) | 1.5 |
Warranty
The Eccotemp L5 has a 1-year warranty period.
Final Thoughts
The best gas tankless water heaters can be installed inside or outside and adapted to any family size.
You can connect POU systems in series to deliver hot water to your shower without breaking the bank on whole-house systems.
That said, many gas tankless water heaters can reach up to 11 GPM, which is perfect for larger families.
To create this list, we looked at the tankless water heaters’ efficiency ratings, flow rates, and environmental impacts.
We hope you found this helps you choose your next GTWH!
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