Reviews of the Best Tankless Water Heaters of 2024
Switching from a traditional hot water tank to a tankless model is one of the best things you can do for your home and your water.
A tankless water heater will heat your water without taking up too much room in your home or driving up your energy bills. That said, there are so many of these systems on the market that it
can be hard to identify the best tankless water heater for you.
We understand how intimidating it can be to pick the right tankless water heater for your home, which is why we put together a list of tankless water heater reviews to help you make a educated purchase..
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Top 10 Best Tankless Water Heaters
Reviews of 2024
Main Features:
- Flow Rate: 9.8 GPM
- Min BTU: 15,200
- Max BTU: 199,000
- Energy Factor: up to .96
- Voltage: 120 volts
- Weight: 33.1 Kg
- Dimensions: 31.8 x 25.4 x 66 cm
- Recirculation capability
- Concentric % PVC
- Condensing technology features w/dual heat exchanger
Product Overview: If you are looking for the best gas tankless water heater for your home, look no further than the Rinnai RUR98iN Ultra Series. This model is considered by many to be one of the best ever produced for residential use.
Armed with an impressive 96% efficiency factor and the ability to provide 9.8 GPM ( gallons per minute ) of hot water flow at nearly any incoming water temperature, this water heater by Rinnai
is capable of replacing traditional tank water heaters in nearly any climate.
Freeze Protection: What’s also worth mentioning is that the Rinnai models feature freeze protection. This means that the brand’s models offer freeze protection for temperatures as cold as -22° F (-30° C), or for
indoor models as cold as -4° F (-20° C) [1]. This function can protect this brand’s models from any direct wind as long as it is sufficiently supplied with power and gas.
What Makes it Stand Out:
A stand out feature that’s unique to this heater is its Wifi Capabilities. This feature allows you to monitor and change your heating settings over your home network. The water heater is Energy Star certified and also boasts an innovative recirculation line which allows it to produce an endless supply of hot water. It’s worth considering that very few heaters that offer these luxurious features — the investment will easily pay for itself in both savings and ease of use.
Pros
- Can meet any residential needs
- Produced by an industry leader
- Hassle Free Warranty Process
- No Expansion Kit Required
Quiet - A Dual Pipe makes the water heater more efficient by using condensation water
- Freeze Protection
- Energy Star certified
Cons
- Most expensive unit you will find for residential use
- Requires venting and does not come with a venting kit
- Might be excessively powerful for smaller homes
Main Features:
- Flow Rate: 9.8 GPM
- Max BTU: 199,000
- Energy Factor: Up to .96
- Voltage: 120 volts
- Weight: 37.2 Kg
- Product Dimensions 25.4 x 47 x 66 cm
- Ultra low NOx emissions
- Concentric & PVC venting
Product Overview: We can say with confidence that if you’re looking to provide on-demand hot water for your whole house, then the Rinnai RUC98iN Ultra Series is the tankless water heater
for you.
Installation: We recommend professional installation since the Rianni RUC908iN Ultra Series requires a natural gas hook up. It’s important to note, as with any water heater, that it may take up to 20 seconds for the water to heat up from this heating system to the faucet. That said, once it’s warmed up, this natural gas tankless water heater will provide an unlimited amount of hot water and slashed energy bills.
What Makes it Stand Out: With the ability to produce a staggering 9.8 GPM of hot water with a temperature rise of 50 Degrees Fahrenheit, this tankless water heater is perfect for nearly every home. Many of these water systems aren’t capable of providing hot water for an entire house, due to the fact that most natural gas tankless models don’t have the same gallons per minute water flow rate as this model.
Pros
- Can meet nearly any capacity need
- Produced by an industry leader
- Hassle Free Warranty Process
- No Expansion Kit Required
- Quiet
- Dual Pipe makes unit more efficient by using condensation water
- Freeze Protection
Cons
- Most expensive unit you will find for residential use
- Requires venting and does not come with a venting kit
- Gas water heating might be excessively powerful for smaller homes
Main Features:
- Flow Rate: 4.68 GPM
- Weight: 3.63 Kg
- Voltage: 240 volts
- No venting required
- 7/3-year warranty
Product Overview: Electric based tankless water heaters have been making strides in recent years. For example, the Stiebel Eltron Tempra Plus has made waves as one of the best electric water heaters in the industry. It is, after all, Stiebel Eltron’s flagship product.
Efficiency: With capabilities to provide an impressive 4.0 Gallons Per Minute and attain incoming water temperatures of 72 Degrees Fahrenheit, this is truly one of the most powerful and efficient electric heater systems available on the market today.
What Makes it Stand Out: Our favourite feature of the Stiebel Eltron Tempra is its easy to use digital controls. Its small and sleek design allows you to install it nearly anywhere, from under the sink to behind a furnace or in a small utility closet. It uses solar as a power source, making it highly efficient — in fact, it can nearly match the energy costs of the best natural gas tankless water heaters or, in some cases, outperform them significantly.
Pros
- Best in class water flow rate
- Trusted by many verified online purchases and reviews
- Great warranty for peace of mind
- Industry leader
- Easy to install
Cons
- Slightly more expensive than other models
- Will require 2+ units to provide for an entire house
Full Review: Stiebel Eltron Tempra Plus 24 kW
Main Features
- Flow Rate: 3 GPM
- Weight: 4.99 Kg
- Size: 4.99 Kg
- Voltage: 240 volts
Product Overview: If you are in need of a simple hot water heater to put under your sink or in a new powder room, then at 240-volts, is the right unit for you. This unit is perfect even if your incoming water temperatures are quite cold, because it is able to provide a 1.5 GPM flow rate with a temperature rise of 50 degrees Fahrenheit.
EcoSMART ECO Model’s GPM: Generally, this type of heater isn’t capable of handling high gallons per minute flow rate. For simple purposes, however, this unit from EcoSMART will be more than enough for nearly any home — regardless of its incoming water temperature.
What Makes it Stand Out:
EcoSMART is a highly trusted brand and for good reason. Their tankless water heater has been a leading seller for three years straight, and is known as one of the most efficient units on the market — it even has the reviews to back it up!
Pros
- Great value, flow rate and quality for the price
Trusted by many verified online purchases and reviews - Lifetime warranty for peace of mind
Digital temperature control - Easy to install
Cons
- Isn’t capable of handling high GPM flow rate
- Larger unit than expected
Full Review: EcoSmart ECO 27 Tankless Water Heater
Main Features:
- Flow Rate: .26 GPM (MIN) 9.5 GPM (MAX)
- Energy Factor: 0.94
- Weight: 35.5 Kg
- Size: 47 x 24.8 x 69.8 cm
- Voltage: 120 volts
- Stainless steel
- Condensing heat exchanger
- 2-Pipe Direct Vent System
- Didgital (UMC-117) remote control
10-Feet of thermostat wire included
Product Overview: The Rheem RTGH-95XLN Prestige is one of the best outside tankless units you can find on the market. The model comes with an EZ link cable that will allow you to connect the unit to another and boasts a digital temperature display to make it easy to monitor its progress.
Energy Efficient: The Rheem RTGH-95XLN Prestige is an incredibly efficient unit as it is compact and conserves energy. In fact, its intelligent electronic controls were specifically designed to increase the unit’s safety and efficiency.
What Makes it Stand Out:
In addition to being high quality and well-rated, the Rheem RTGH-95XLN Prestige also boasts a high energy factor (94%) and one of the highest flow rates (9.5 GPM). The best part? The water heating system requires no ventilation and can meet the needs of most homeowners!
Pros
- One of the most trusted brands in the business
- Standard 10 year warranty
- Leading energy efficiency rate at 94% (Compared to other outside units)
- High energy factor & high flow rate at 9.5
- Gallons Per Minute
- Does not require any ventilation
- Stainless Steel
Cons
- While it seems expensive up-front, the high energy efficiency will make it cheaper over time.
Main Features:
- Weight: 54 pounds
- Dimensions: 14 x 10 x 26 inches
- Flow Rate: 8.4 GPM
- 35-Degree Rise
- UMC-117 remote control
- 10-Feet of thermostat wire is included
Overview: If you’re considering a heater outside to save a few dollars, then the Rheem RTG-84XLN is the best tankless water heater for you.
Energy & Cost Savings: With a strong flow rate of 8.4 GPM, which is satisfactory for most homeowners, this “middle of the road” unit with strong efficiency and low emissions is ideal. Compared with a hot water tank run on natural gas, this model will not only save you a ton of money but save tons of carbon from being emitted into the atmosphere as well.
What Makes it Stand Out:
One of this model’s greatest features is its remote control capabilities — this is best in the winter when you don’t have to go outside to adjust your settings. There’s a lot to love about the heater that boasts an environmentally conscious design to ensure efficiency and low.
Pros
- From leading brand Rheem
- Standard 10 year warranty
- Leading energy efficiency rate at 84% (Compared to other units)
- Strong flow rate at 8.6 Gallons Per Minute
- Does not require any ventilation
Cons
- May not last as long in harsher climates
Main Features
- Flow Rate: 6.6 GPM
- BTU: 140,000
- Energy Factor: 0.81-0.83
- Weight: 16.8 Kg
- Volts: 120 volts
- Dimensions: 17 x 35.1 x 51.6 cm
Perfect for Small Homes & Budget-Friendly: This heater is perfect for families on a budget who aren’t looking for a model with all the stops and a hefty price tag to match. The unit is specially designed for small homes and is nice and compact for easy storing — it’s actually the smallest system on the market! It is best used for single point applications.
The system may be small, but it’s equally powerful and is known for its many positive reviews thanks to its durability and compact nature.
Takagi products are well known in the industry (although not as reputable as Rheem and Rinnai), and come highly rated on various online shopping websites. This model boasts the absolute best value in gallons per minute on the market today, thanks to its ability to generate a maximum of 6.6 GPM for under $500.00.
Pros
- One of the most powerful models below the $500 price mark
- Built by a reputable brand name
- Comes with a standard 10 year warranty
- Very easy to maintain, comes apart easily
Cons
- One of the louder units you can find
- 6.6 GPM won’t meet the needs of a medium-sized house
- Only 81% energy efficient, so in some respects, it’s more expensive than high-efficiency counterparts.
Main Features:
- Weight: 54 pounds
- Dimensions: 14 x 10 x 26 inches
- Flow Rate: 8.4 GPM
- 35-Degree Rise
- UMC-117 remote control
- 10-Feet of thermostat wire is included
Overview: If you’re considering a heater outside to save a few dollars, then the Rheem RTG-84XLN is the best tankless water heater for you.
Energy & Cost Savings: With a strong flow rate of 8.4 GPM, which is satisfactory for most homeowners, this “middle of the road” unit with strong efficiency and low emissions is ideal. Compared with a hot water tank run on natural gas, this model will not only save you a ton of money but save tons of carbon from being emitted into the atmosphere as well.
What Makes it Stand Out:
One of this model’s greatest features is its remote control capabilities — this is best in the winter when you don’t have to go outside to adjust your settings. There’s a lot to love about the heater that boasts an environmentally conscious design to ensure efficiency and low.
Pros
- From leading brand Rheem
- Standard 10 year warranty
- Leading energy efficiency rate at 84% (Compared to other units)
- Strong flow rate at 8.6 Gallons Per Minute
- Does not require any ventilation
Cons
- May not last as long in harsher climates.
Main Features:
- Flow Rate: 6.6 GPM
- BTU: 140,000
- Energy Factor: 0.81-0.83
- Weight: 16.8 Kg
- Volts: 120 volt
- Dimensions: 17 x 35.1 x 51.6 cm
Overview: If you are looking for that “middle of the road” system that is both high quality and affordable, then look no further than the Takagi T-KJr2-IN-NG.
Budget Friendly System: This heater is perfect for families on a budget who aren’t looking for a model with all the stops and a hefty price tag to match. The unit is specially designed for small homes and is nice and compact for easy storing — it’s actually the smallest system on the market! It is best used for single point applications.
The system may be small, but it’s equally powerful and is known for its many positive reviews thanks to its durability and compact nature.
What Makes it Stand Out:
Takagi products are well known in the industry (although not as reputable as Rheem and Rinnai), and come highly rated on various online shopping websites. This model boasts the absolute best value in gallons per minute on the market today, thanks to its ability to generate a maximum of 6.6 GPM for under $500.00.
Pros
- One of the most powerful models below the $500 price mark
- Built by a reputable brand name
- Comes with a standard 10 year warranty
- Very easy to maintain, comes apart easily
Cons
- One of the louder units you can find
6.6 GPM won’t meet the needs of a medium-sized house - Only 81% energy efficient, so in some respects, it’s more expensive than high-efficiency counterparts.
Overview: Whether you’re camping or roughing it at a cabin, there is nothing quite like a hot shower at the end of the day when you spend your day outside. The Eccotemp L10 Portable Outdoor Propane Tankless Water heater is the best model for this purpose.
Great for Outdoor Installation: The Eccotemp L10 heater is specially designed for outdoor purposes. It can provide you with an endless supply of hot water at your cottage, cabin, camping site, or any other outdoor area. It boasts a flow rate of 2.65 Gallons Per Minute and its 2 “D” cell battery ignition makes sure there is no overheating thanks to the fact it only starts when water
runs.
What Makes it Stand Out:
This propane tankless water heater is able to heat nearly any incoming water temperature and provide refreshing hot water to your shower outside. This model works with the standard 20lb propane tank and comes with the standard garden hose
adapter. Simply buy it, hook up your gas line and garden hose, and you are off to the races! The unit is even capable of handling water temperatures below freezing (32 Degrees Fahrenheit).
Pros
- Powerful unit capable of handling any incoming water temperature
- Backed by one of the biggest brand names
Industry leading warranty - Works with standard garden hose and BBQ propane tanks
Cons
- Water can take a while to heat up
- Uses more propane than you would expect
- The product doesn’t come with an external cover to keep it protected, so we suggest purchasing one
Full Review: Eccotemp L10 2.6 GPM Portable Tankless Water Heater.
Tankless Water Heater Buying Guide
Why Go Tankless?
Tankless heaters provide instant and on-demand hot water, whereas traditional tanks keep a fixed amount of water hot at all times [2] — this is an important distinction. Whether it is gas or electric, a traditional tank uses energy all day long.
The thing about these systems is that they only draw power when hot water is demanded — this makes them energy efficient and cost-effective. According to Energy.gov, tankless heaters can offer up to 37% energy savings [3].
Types of Tankless Water Heaters
There are various types of tankless water heaters; you can have one indoors or outdoors, fueled by gas or electricity.
It can be a challenge to identify the best unit for your home, which is why we’ve compiled a best tankless water heaters review guide It’s crucial that you are aware of the advantages and disadvantages of your options.
Gas:
Natural gas tankless water heaters use gas to heat the water instead of electricity.
Advantages:
- Much more powerful, able to heat multiple faucets at once
- Lower cost than electricity in most cases
Able to heat water from cold incoming water temperatures
Disadvantages:
- More expensive than electric heaters
- Emit emissions directly from the unit
- May require ventilation, depending on the unit and placement
Electric
Electric water heaters use electricity instead of gas to heat up the water in your tank. They are typically smaller and more affordable than gas units.
Advantages:
- Doesn’t directly emit CO2 (your electricity may come from a coal plant, however)
- More affordable than a gas water heater
- Doesn’t require any ventilation
Disadvantages:
- Most homes would require multiple units to produce the same amount of hot water as a gas powered unit
- Require more maintenance due to limescale and calcium build-up
- Electricity is generally more expensive than gas
- Buying a single, large, gas powered tankless water heater or buying multiple tankless electric water heaters can produce the same hot water output for roughly the same initial cost.
Buying a single, large, gas powered tankless water heater or buying multiple tankless electric water heaters can produce the same hot water output for roughly the same initial cost.
Energy Star Certified Models
Products earn Energy Star certification if they are proven to be cost-effective, energy-efficient, and environmentally friendly. To be Energy Star certified, a product must be tested to ensure that it meets efficiency specifications [4].
What Size Unit Do I Need?
Of the many tankless water heaters on the market, which size is best suited for your home? For the purposes of this chart, we will assume that your home’s incoming water temperatures are 67 degrees Fahrenheit or above. If not, you will generally want to play it safe and invest in one of the best tankless water heaters reviewed in our guide.
| Demand Type | Size |
|---|---|
| Bathroom Sink | 0.5 GPM |
| Standard Shower | 2.5 GPM |
| Low-Flow Shower | 1.5 GPM |
| Dishwasher | 1.0 GPM |
| Washing Machine | 1.5 GPM |
| Kitchen Sink | 0.5 GPM |
| Laundry Sink | 1.0 GPM |
| Dwelling | Bathrooms | GPM |
|---|---|---|
| Apartment / Condo | 1 | 3.0 GPM |
| Small House (<1000 sq. ft.) | 1 | 4.0 GPM |
| Average House (<1600 sq. ft) | 2 | 7.5 GPM |
| Large House (1600+ sq. ft) | 3+ | 10+ GPM |
1 bedroom 1 bathroom apartment with appliances:
A normal apartment with a bathroom sink, shower, kitchen sink and dishwasher (but no washing machine), you would need a 4.0 GPM flow rate to run everything simultaneously. One option would be to buy two electric systems — one for the restroom and one for the kitchen.
2 bedroom 2 bathrooms
A 2 bedroom 2 bathroom house will generally have 2 showers, 2 restroom sinks, a kitchen sink and dishwasher as well as a washing machine. In order to run everything at once, you will need at least 8.5 GPM of flow rate. A homeowner typically won’t need to run everything at once, in which case they could get away with 7.5 GPM. Keep in mind, however, that you need more power in the winter for higher temperatures to rise.
4 bedroom 3 bathrooms, in-law suite
A large home with 3 showers and restroom sinks, and 2 kitchens with 2 dishwashers and 2 washing machines would require flow rate over 15 GPM to provide hot water to all faucets at the same time. While this is an unlikely scenario, it is a good idea to have at least two gas-powered tankless water heaters to provide sufficient demand to the entire house.
Indoor vs Outdoor Systems
Even though we typically recommend buying an indoor system, you have to consider two important factors before ruling out investing in an outside heater.
Space: If space is a constraint for you, you can save space by placing your system outside. Proportionally speaking, a small cabin or cottage, or a multi-unit building that requires multiple units, can save a lot of indoor square footage using this kind of system.
Sound: Some heaters make more noise than others, although all of them make some noise. In a small enclosed space, this can be irritating and can be avoided by placing the unit outside.
Ventilation: If for any reason you foresee your system’s ventilation being overly complicated or constrained, you may want to place it outside to avoid all ventilation concerns. The truth of the matter is that sometimes ventilation takes up more space than is available.
Incoming Water: Hardness and Temperature
- Temperature
If your incoming water temperature is below 50 degrees Fahrenheit, that’s an indicator that you’re better off with a gas-powered tankless water heater.
Other heaters are simply not powerful enough to raise the temperature to more than 30 degrees Fahrenheit. Unless you are willing to give up hot water during the winter, you’re likely better off going with a gas-powered unit.
On the other hand, if you have a cottage or cabin that is only used in the summer, then you may want to consider a different heater for your water.
Map of incoming water temperatures in the United States [5]
- Hardness:
If your water is particularly hard (i.e. you need to use a softener), then you will need to either maintain your system more regularly or use additional equipment to soften the water before it
enters the heater. Limescale and calcium build up can destroy your unit if it’s not cleaned
regularly.
Map of water hardness in the United States [6]
How do Tankless Water Heaters Work?
All tankless water heaters work more or less the same way. They heat water directly without the use of a storage tank. When a hot water tap is used, the incoming cold water enters a heating chamber and is then heated by a powerful heat exchanger.
For those not familiar, a heat exchanger is a tool that allows heat to transfer between sources. You’d also find a heat exchanger in your other household appliances i.e. your refrigerators and air conditioners [7].
The best tankless water heaters on the market are made with different materials and are used for varying purposes. It’s important to do your research and read our tankless water heater review guide to ensure that you get the right heater for your unique needs.
Water Heater Cleaning & Maintenance
If you invest in one of the best tankless water heaters on the market, you are going to want to take care of it.
If you are a handy person who’s familiar with water heater maintenance, check out these quick refresher videos on how to flush your heater:
It’s also important to clean out the filter, which can accumulate some sediment as well. This video quickly explains how to do this:
If you are a beginner and have never performed maintenance before, don’t be nervous about maintaining your tankless water heater. This 8 minute video takes you through the process step by step.
It’s important that you don’t use store-bought descaling products, as they contain harmful chemicals that can run off in your tap water. As mentioned in the video below, use all-natural, pure white vinegar. Vinegar is completely safe for humans to consume, so no need to worry if you don’t flush 100% of the vinegar out of the system.
Frequently Asked Questions About Tankless Water Heaters
There are some common questions that get asked about these water heating systems and how they work — and if they are even worth it to begin with:
What is the best rated tankless water heater?
We’ve only listed water heaters that have been rated 4+ stars on Amazon on our tankless w list of water heater reviews.
What brands of water heaters are the most reliable?
The most reliable water heater brands are Rinnai, Rheem, Eco Smart Eco, Stiebel Eltron, and Takagi.
How reliable are tankless water heaters?
Tankless water heaters are exceptionally reliable as they produce endless hot water, leak less, live longer than other models, and generally are a lot more compact than others.
What is a condensing tankless water heater?
Condensing tankless water heaters use the thermal energy of exhaust gases to heat water. It recycles any extra heat by only venting vapour when it’s no longer needed. These systems run above 90% efficiency, are less expensive to vent, and are much more efficient. This saves homeowners money in the long run!
Why do I need a heating system with a high flow rate?
A flow rate is quite literally the rate of water flow. It’s the rate at which water is passing through your heating system; this measurement is important because the faster the water passes through, the quicker the water gets heated!
What is a non-condensing tankless water heater?
A non-condensing tankless water heater is more wasteful, as it loses 20% of heat when its condensation gets vented.
What is a high energy factor?
This is a measure of energy efficiency. This means, quite literally, that the higher a tankless water heater’s energy factor, the more energy-efficient it is — and the more likely it is to slash your energy bills! [8]
A product’s energy factor is determined by how much hot water it produces per unit of fuel it uses on a given day. [9]
Are there rebates available for these systems?
Some cities like Ontario offer a rebate for these energy-efficient tankless water heating systems to encourage people to be less wasteful with their water and conserve!
Is getting a tankless water heater worth it?
Getting a tankless water heater is worth it when you consider the space and money you save. Because they only heat up water as you need it, these heaters are also energy efficient.
Conclusion: The Best Tankless Water Heater
Tens of thousands of households save money every month by having a tankless water heater. These heaters save homeowners money, and help the environment by requiring less coal to be burned in power plants — it’s a win-win situation.
Those who choose a traditional hot water tank for their home, on the other hand, are spending an arm and a leg renting these tanks from utility companies. If you switch from a hot water tank rental to a tankless system, you can reduce your monthly utility bill drastically! After all water heating makes up 15-25% of our water heating bills [10].
The drawback of these tankless heaters, however, is that they require routine maintenance. That said, our guide just goes to show that this maintenance is pretty easy, straightforward and safe.
It goes without saying that these water systems are well worth the investment. We know that the countless heaters on the market can be intimidating, which is why we based our tankless water heaters reviews based on the purposes they are most suited for.
We hope that our guide to some of the best tankless water heaters helps you choose the best water system for your home, outside, cabin, cottage, RV or simply to put under your sink. You deserve hot water everywhere you go!
