15 Best Tankless Water Heaters - (Reviews & Guide of 2020)

In recent years there has been a great evolution in development of tankless water heaters. If you are curious about how to find the best tankless water heater and how they can help your home you have come to the right place.

Tankless water heaters are now becomming a popular choise to replace the big tanks regular water heaters in peoples homes as they provide you with hot water on-demand in the kitchen, bathroom, or any other room you want to install one.

In this article we are going to provide you with a number of tankless water heater reviews that have the best ratings from the best brands so you can decide for yourself which heater is the best for you.


Tankless Water Heater Reviews [Updated List]

Ecosmart ECO 36

  • Sleek and compact design
  • Digital output with temperature display.
  • Pipe Fittings:3/4 inch NPT
  • Required Breaker: 4 x 40 A

Rinnai RUC98iN

  • Concentric or PVC venting option
  • The space-saving design
  • Ultra low NOx emissions
  • 199,000 max BTU

Rinnai RL94eP

  • Up to 9.4 GPM hot water flow rate
  • Circ-Logic technology
  • Outdoor Installation Only
  • Endless hot water for your entire home

Noritz NRC661-DV-NG

  • Endless hot water
  • Can be vented with Schedule 40 PVC Pipe
  • High Efficiency
  • Low Nox


1. Ecosmart ECO 36 Tankless Water Heater

Ecosmart ECO 36

  • Sleek and compact design
  • Digital output temperature display
  • Pipe Fittings:3/4 inch NPT
  • Required Breaker:4 x 40 A

The Eco 36 is the largest in the line of EcoSmart electric tankless water heaters but still saves much more space over a typical water heater tank at 17 x 19 x 3.8 inches. We’ve included it in our search for the best tankless water heater because it’s at the low end of the price range and is a very economical choice.

Similar to the Rinnai RL94eP, the Eco 36 has a self-adjusting technology that will simply change its energy output during the highest demand times. Some families might shower more often before school or work in the morning, or possibly use more hot water at night for baths or washing dishes and clothes. It is so helpful to have a water heater that you can program for your needs, instead of rushing through your water needs to conserve hot water. The Eco 36 also offers a digital thermometer panel for your convenience.

For installation, this unit requires a 4 x 40 double-pole drawer and 150 amps on the circuit breaker. If you are unsure about the electrical ability of your breaker panel, please consider asking a professional electrician to look over your plans before purchasing this tankless water heater.

Read the full EcoSmart Eco 36 Review here.


2. Rinnai RUC98iN Tankless Water Heater

Rinnai RUC98iN

  • Concentric or PVC venting option
  • The space-saving design
  • Ultra low NOx emissions
  • 199,000 max BTU

While this unit is at the higher end of the price range, users rave about its features. Rinnai is pretty proud of the fact that it is the only water tank manufacturer to offer two installation options in one unit—saving you the hassle of buying extra parts. This Rinnai tankless water heater offers two options for natural gas venting—both concentric and PVC pipe options are found on the top of the unit for convenient access during installation.

This concentric vent design is very unique with important safety benefits. The concentric vent means that it holds both intake and outtake pipes, so the vent is cool to the touch as the warm air is insulated inside. If an intake or outtake pipe develops a leak, the air stays in the concentric vent and does not enter the home. The dangers of a gas leak are immeasurable; from fire and combustion to carbon monoxide poisoning. But with this model, you can rest easy at night.

The Rinnai RUC98iN is quiet, compact, and gives you immediate hot water when you want it. One of the main differences with tankless water heaters is because the water is heated on demand, there can be a slight drop in water pressure if multiple showers are running at the same time. Also, be sure to give a tankless unit about 8-10 seconds to clear the cold water out of the pipes before jumping into the shower expecting hot water.

The Rinnai RUC98iN is certified through Energy Star with a rating of 0.96. This tankless water heater will not only work to save you money on your energy bill, but will also save space—it is about the size of a small suitcase at 10 x 18.5 x 26 inches.

Read the full Rinnai RUC98iN Natural Gas Tankless Water Heater Review here.


3. Rinnai RL94eP

Rinnai RL94eP

  • Up to 9.4 GPM hot water flow rate
  • Circ-Logic technology
  • Outdoor Installation Only
  • Endless hot water for your entire home

The Rinnai RL94eP comes in with a higher price tag, but for propane users who need an outdoor unit, this sleek water heater confidently fits the bill. In a comparison of tankless water heaters, you’ll definitely want to keep the Rinnai luxury line in mind. Outdoor water heaters dispel the costly and time-consuming venting needs of indoor units. If you live in a climate that can support an outdoor unit, the RL94eP is a great option to consider.

If you want one of the highest GPMs of hot water for your home or business, the Rinnai RL94eP offers an impressive 9.4 GPM. That translates into at least five different simultaneous demands for hot water; such as two showers, a dishwasher, washing machine, and a sink, all at the same time.

The Rinnai RL94eP is Energy Star certified with an energy factor of 0.82. It also features a patented recirculation program that cycles water through at peak demand times (like the early morning hours) to provide the most efficient and best water temperatures for your family. For those with young children in the home, you can depend on the certainty of the Rinnai’s temperature lock to prevent scalding or burns from the tap or the showerhead.

Read the full review on Rinnai RL94eP Propane Tankless Water Heater here.


4. Noritz NRC661-DV-NG

Noritz NRC66DVNG

  • Endless hot water
  • Can be vented with Schedule 40 PVC Pipe
  • High Efficiency
  • Low Nox

The Noritz NRC661-DV-NG is a good tankless water heater for a small to mid-sized family home. It falls just about in the mid-range of prices for a tankless water heater, and is Energy Star certified. Noritz has been making water heaters for over 60 years, and it shows in this well-engineered model. At 6.6 GPM, the NRC661-DV-NG can easily handle multiple showers, a clothes washer, and a dishwasher simultaneously.

If your home is already using natural gas for your dryer or stove, the Noritz would be a good choice for installation with your already existing gas lines. This NRC661-DV-NG can also be installed with schedule 40 PVC pipe for the venting, so that should help reduce installation costs, as it is very economically priced. This is a condensed model that has a cool exhaust, versus other models that have a hot exhaust.

A highly efficient tankless water heater, this unit should save you 10-20% on your natural gas costs over time. Paired with the opportunity to have endless hot water when you need it (which is always regulated with a digital thermometer on the water output), and you have an ideal combination of features in this Noritz NRC661-DV-NG.

Read More about the Noritz NRC661 Tankless Hot Water Heater here.


5. Titan Tankless N-270

Titan N-270 27

  • Save up to 60% on hot water energy
  • 10/1 year warranty
  • Wall-Mounted installation
  • Measures 12 x 4 x 11 in

Northern climate residents who have to raise the water temperature fairly significantly for hot water needs should look at the Titan N-270. This is the best tankless water heater in the Titan lineup. If you are also looking for an electric unit that will save you up to 60% on your energy costs over your previous water heater tank, this is it!

Titan water heaters have been made in the USA for 30 years. This totally revamped 2019 model has been engineered specifically for homes with higher needs. Users in colder climates that need to raise incoming water temperature even higher than mild or temperate climates would be a good fit for the Titan. It would also be ideal for homes that have multiple fixtures in large bathrooms like jacuzzi tubs or multiple shower-heads or sprayers in the shower.

With a size of just 11.5″ W x 10.5″ H x 3″ D, the Titan N-270 is small but powerful. Because it is designed to power such a large water draw, the electrical demands for this unit are two 60 AMP breakers with 6 gauge wiring. This will easily fulfill the needs of a large whole home with 4 GPM while balancing very nicely as one of the lowest-priced units on our list.

Read the full review on Titan N-270 Heater here.


6. Takagi T-H3-DV-N

Takagi T-H3-DV-N

  • Compact, Space saving
  • Computerized safety features
  • Endless hot water, On-demand usage
  • Ultra-Low NOx Emissions

At 10 GPM, this Takagi T-H3-DV-N outperforms nearly all of the other tanks on the list. This large-capacity tankless water heater performs well in a small commercial application or a large residential space. If you maximize the temperature at 131 degrees F, it will fill your large bathtub almost as quickly as a 50-gallon water heater tank. With gas inputs of 199,000 BTU, in warmer climates, it can provide enough hot water for up to four showers, and up to three showers in colder climates.

Because this is a condensing high-efficiency unit, you will have to allow for a drainage area for your condensation. Be sure to have a drain nearby to the installation point to collect the condensation water. The manufacturer allows for venting with a schedule 40 and 80, PVC and CPVC, and ABS, as well as stainless steel.

This Takagi T-H3-DV-N does satisfy the 2012 SCAQMD rule 1146.2 for ultra-low NOx emissions. All of the connections in the power-vented tankless water heater are silicone-sealed to prevent carbon monoxide leakage. Because of its efficiency and ability to vent almost no hot air exhaust, this unit is Energy Star certified.

Due to its large size and high capacity for heating water, this unit does come in at the higher end of the price range. Its features definitely place it in the top three listings in our tankless water heater review. If you have high water needs, with this Takagi, you are getting endless hot water at a high water flow!

Read the Takagi T H3 Indoor Tankless Water Heater Review here.


7. Chronomite SR-30 208

Chronomite Labs 6240W

  • Country Of Origin: United States
  • Model Number: SR-30/208 HTR
  • Item Package Weight: 2.02 lb
  • Measures 9.6 x 2.8 x 6.2 in

Some homes would really benefit from a point-of-use tankless water heater like this Instant-Flow version from Chronomite. If you have a sink that is located in an upstairs bathroom far from your water heater, or if you want hot kitchen water right away, consider this version that only uses 30 amps of energy.

The Chronomite SR-30/208 HTR sits at a nice low price point thanks to its 1.0 GPM flow rate and its 9.6 x 2.8 x 6.2 inch size. It should fit easily under a kitchen or bathroom cabinet and be hidden away from sight. For installation, this unit has two mounted chrome compression fittings and uses 3/8-inch cold water inlet and outlet connections. To hook up the electrical portion, simply punch out the rear electrical knock-out and you will have access to the wiring.

Chronomite can boast about its microprocessor technology, which delivers instant hot water in two seconds instead of the standard six seconds of its competitors. You can pre-set the technology to your desired temperature to prevent accidental burns or scalding. This feature is especially helpful for homes with small children or for those sleepy early mornings. If you choose the Chronomite, you will be more efficient with your electrical use and reduce your hot water delivery time.

Read more about Chronomite SR-30/208 HTR SR Series Tankless Water Heater here.


8. Ariston GL4S Electric Mini-Tank Water Heater

Ariston GL4S

  • 120 volts, 1500 watts
  • No hard wiring needed
  • Point-of-use 4-gallon
  • Measures 13.75 x 13.50 x 13.75 in

For those who would like to try a point-of-use water heater, this Ariston GL4S model is one of the easiest to install. Simply plug the unit into the wall near the sink, with no hard wiring required. Use the cold water line to attach this mini-heater, and you are ready to go. It holds 4 gallons of hot water right at the faucet where you will need it. It is virtually effortless to get your hot water quickly.

This updated version of the Ariston GL now has a sensing probe that more accurately maintains the proper temperature and can adjust the temperature more quickly. The manufacturer does offer a 6-year limited warranty on the heating exchanger and a 1-year limited warranty on the parts.

Because of its small size and power needs, this mini tank is about half the price of the lowest priced electric tankless units on our list. For installation, you will need enough room for the 14” x 14” deep size. A good application for this tank is if you have a sink that is far from your hot water heater, and it takes a long time to run the faucet and get hot water to the tap.

Read the full article on Bosch GL4S Ariston here.


9. Rheem RTG-95XLN

Rheem RTG-95XLN

  • Natural Gas Tankless Water Heater
  • 9.5 gal/min. at 35-Degree Rise
  • UMC-117 remote control
  • Low Nox Version

You will find this Rheem RTG-95XLN at the top of the price range due to its excellent features and its natural gas energy source. Engineered to be installed outdoors for mild or temperate climates, this natural gas tankless water heater does also come with a remote temperature controller. Thankfully you will not have to walk out to the unit to adjust the temperature manually.

Rheem has done a great job with the 9.5 GPM output for users who demand high volumes of hot water. 9.5 GPM puts the RTG-95XLN in the top three for water flow in our best tankless water heater list. Considering the low-NOx emissions from this tankless water heater, it is certainly no surprise that it has a 0.82 energy factor, with its all-copper heat exchanger.

When your home has a high on-off frequency, it can be hard to minimize the cold water stored in pipes before the hot water reaches the tap. The Rheem RTG-95XLN has been built to reduce the “cold water sandwich” common in tankless water heaters with its hot-start programming. You will be grateful for the technology behind this programming when you are standing in the shower, bracing yourself for the cold shot of water and it comes out hot!

Read our full review on Rheem RTG-95XLN Outdoor Tankless Natural Gas Water Heater here.


10. EcoSmart ECO 11

EcoSmart ECO 11

  • Patented Self Modulating Technology
  • 99.8-percent energy efficient
  • Uniform Energy Factor: 0.98
  • 13KW at 240 Volts

If you have lower hot water needs but still want the ease of an electric tankless, the EcoSmart ECO 11 is ideal for a small apartment-size space. The ECO 11 can be used for multiple or single applications depending on your climate. You can use it to provide hot water for two faucets at 1.3 GPM in the coldest climates, or a shower and two faucets simultaneously in warmer climates at 2.7 GPM.

Expect the ECO 11 to pull 13 kilowatts for its power needs. It draws 57 amps and requires a 60 double-pole for installation. EcoSmart’s sizing offering is based on a 240-volt electrical service. Be sure to check your existing electrical panel to ensure you have adequate electrical draw space for the ECO 11.

With a 50% savings in water heater costs, the ECO 11 should help you reduce your electric water heating needs fairly quickly. This unit will also save a sizable amount of space in the utility area, with the height, width, and depth measuring 6.5 x 13.5 x 10 inches, respectively. Especially if you’re removing an existing tank, it would be nice to have that extra space for storage or easy access to other utilities in your basement or utility closet.

An electric hot water heater from EcoSmart will also give you one of the most extensive product warranties on the market. If you’re new to tankless water heaters, a reputable manufacturer might be important to you. Customers are very happy with the customer service support from the team at EcoSmart—technicians are easily available to help with sizing, installation, and maintenance questions. EcoSmart offers a lifetime warranty on the electronics, the stainless steel exchanger, and the heating element.

Read the full article on EcoSmart ECO 11 here.


11. Takagi T-KJr2-IN-NG

Takagi T-KJr2-IN-NG

  • 140,000 BTU. Voltage: AC 120V
  • 6.6 GPM max flow rate
  • Energy factor of 0.81-0.83
  • Measures 6.7 x 13.8 x 20.3 in

As a smaller natural gas tankless water heater option (6.7 x 13.8 x 20.3 inches), Takagi recommends this unit for apartment residents or smaller family homes with one or two bathrooms. That smaller size also brings a lower price tag, for those looking for tankless water heaters at economical prices for their home.

For installation, Takagi requires 4-inch category III stainless steel venting for the T-KJr2-IN-NG. Some other units give piping and material options for venting, but this unit requires the stainless steel. Some installers have suggested mounting your unit as near as possible to your vent, and configuring your water and gas lines a little bit farther to the Takagi, in order to save money on the more expensive stainless steel venting.

It is also Energy Star certified with an energy factor range of 0.81-0.83. If you are looking to save money on your natural gas bill and use hot water on demand, this is a great unit to try. The Takagi T-K Jr. 2 offers a maximum flow rate of 6.6 GPM (gallons per minute), which is typically enough to run a dishwasher, a shower, and a washing machine all at the same time. If it happens that more hot water is needed, the water pressure will drop slightly in the faucet or shower-head.

Read the full Takagi T-KJr2-IN-NG Indoor Tankless Water Heater Review here.


12. Rheem RTG-84XLN

The Rheem RTG-84XLN falls in the middle of the price range due to its 8.4 GPM water flow and its natural gas energy source. Engineered to be installed outdoors for mild or temperate climates, this natural gas tankless water heater comes with a remote temperature controller. It is especially convenient that you will not have to walk out to the unit to adjust the temperature manually.

Rheem offers a super line of mid-range tankless heaters, this one with an 8.4 GPM flow output for users who demand a high volume of hot water. Also, if you want to save more energy, there is a water savings setting that reduces the water flow in the pipes until the heater can reach your ideal temperature, and will then ramp up and increase to your desired flow rate. This unit is also part of Rheem’s low-NOx emission line and offers a 0.82 energy factor with its all-copper heat exchanger.

Be sure to check the specifications in the manual and be certain that your gas lines conform to the pipe requirements for installation. The RTG-84XLN is compatible with ½-inch gas lines. This unit is for outdoors, so there are no venting needs during setup and installation. Another perk of this outdoor natural gas tankless heater is its 3/5-inch concentric vent system with integrated condensation collector, which saves you the headache of installing drain lines like condensing indoor units will need.

Read our full take on Rheem RTG 84XLN here.


13. EcoSmart ECO 18

The EcoSmart ECO 18 gives consumers a sizeable draw of hot water with a flow rate of 2.5 GPM. This should be adequate for a large apartment or townhome or even possibly a small home with moderate water needs. If you are in a colder climate, the ECO 18 can handle powering one shower and one sink at the same time. In warmer climates, the water does not need to be heated as much, and it should be able to heat water for two showers and two sinks.

True to its name, the ECO 18 does pull 18 kilowatts for its power needs, draws 75 amps, and requires two 40 double-poles for installation. EcoSmart’s size offering is based on a 240-volt electrical service. Be sure to check your existing electrical panel to ensure you have adequate electrical draw space for the ECO 18.

With a 50% savings in water heater costs, the ECO 18 should help you reduce your electric water heating needs fairly quickly. This unit will also save a sizable amount of space in the utility area, coming in at 17 inches high, 14 inches wide, and 3.75 inches deep. Especially if you’re removing an existing tank, the extra space in your basement or utility closet will come in handy.

An electric hot water heater from EcoSmart will also give you one of the most extensive product warranties on the market. If you’re new to tankless water heaters, a reputable manufacturer may be important to you. Customers are very happy with the customer service support from the team at EcoSmart—technicians are readily available to help with sizing, installation, and maintenance questions.

Read the full review on Ecosmart ECO 18 Electric Tankless Water Heater here.


14. Rheem RTG-64XLN

Rheem has done a fine job with the 6.4 GPM output for homes that have low-to-average level hot water needs. The Rheem RTG-64XLN is at the middle of the price range due to its flow rate of 6.4 GPM and its natural gas energy source.

Engineered to be installed outdoors for mild or temperate climates, you will not have to walk out to the unit to adjust the temperature manually because this natural gas tankless water heater comes with a remote temperature controller. This line of Rheem heaters has low-NOx emissions, and this model has a 0.82 energy factor for efficiency. Count on the Rheem RTG-64XLN for standard ½-inch gas line compatibility for easy hookup on outdoor installation.

To save more energy, the Rheem RTG-64XLN features water-saving settings that reduce the water flow in the pipes until the heater can reach your ideal temperature, and will then ramp up and increase to your desired flow rate. RTG-64XLN offers an impressive minimum flow rate of 0.26 GPM, which is standard in the RTG line and the first in the tankless water heater industry. To satisfy the consumer, Rheem has also engineered a minimum activation flow rate of 0.40 GPM, offering instant hot-water even in those low-demand hot water situations.

Read our full Rheem RTG 64XLN Outdoor Tankless Review here.


15. Stiebel Eltron Tempra 24

Rest assured, if you are willing to break away from traditional tank water heaters and try an electric tankless for your home, you will not be disappointed with the Tempra 24 Plus from Stiebel Eltron.

The foolproof digital temperature controls on the Tempra 24 Plus help it stand out from the crowd. This model’s claim to fame is the fact that it self-adjusts and maintains a consistent hot water temperature, no matter the demand, and no matter the duration of water use. That means that multiple showers can be running in a home and you’ll never run out of hot water.

At just over 15 pounds and 21.5 x 19.5 x 8.8 inches, this tankless water heater takes up much less space than traditional water heater tanks. Since it is an electric tankless water heater, the Tempra 24 Plus does require a minimum circuit breaker space of a double pole 2 x 60. While the unit is very reasonably priced, if you are considering purchasing this model, please be sure to factor in the cost of installation by a professional and/or any electrical work that might need to be done. For your convenience, the Tempra 24 Plus does come with a three-year limited warranty (but the product must be installed by licensed personnel).

Read more about Stiebel Eltron Tempra 24 Plus here.


Tankless Water Heater Buying Guide

Benefits of a Tankless Water Heater

One of the most important pieces of advice to remember is that there is no single best choice when it comes to tankless water heaters. Each home is unique in its needs and its energy sources, so what works for someone living in a different climate might not be the ideal option for your home in a cold-climate area. Also, the price of a good tankless water heater will vary greatly based on its capacity and the power source.

For those looking for a comparison of tankless water heaters, you’ll first want to decide whether you prefer an electric or gas tankless water heater. Then, once you consider your hot water needs, you should be able to narrow down your top options based on the gallons per minute (GPM) flow rate that you need for all of the fixtures in your home. One home that has four bathrooms for six occupants might have different energy needs than those empty nesters with a household of two.

If you are building a new home, you have the best opportunity to install a tankless water heater and take advantage of the greatest price savings and energy efficiency. When you are designing your utility area, speak with your builder and plumber to decide how a tankless water heater can fit into your plans. If you have decided to replace an old water heater tank with a tankless water heater, read on to discover the pros and cons of a tankless water heater and see if one would be a good fit for your home.


How Does a Tankless Water Heater Work?

Best Tankless Water Heater ReviewsThe mechanics of a tankless water heater is fairly simple. Cold water enters the unit through your cold water intake pipe. It then snakes through a series of heating elements and exits the unit from the hot water pipe. Within the unit, there are sensors that monitor the intake temperature of the water as well as the output to ensure you receive a precise temperature.  After it is heated, it will travel through your water pipes to your faucet, shower, or other hot water source.

The heating elements within the tankless heater vary in layout based on the energy source: either electricity or gas. Most have a recirculation feature that will reroute the water within the heating elements until it reaches the correct temperature.

It is worth noting that some tankless water heaters will have a feature called a “minimum flow rate” to turn on. You can expect some units to sense the demand at 0.5 GPM, but if you want it lower than that, you might have to turn on a faucet at a fuller speed to trigger the tankless heater, and then reduce the flow to your liking. This would only be an issue if you wanted a slow stream of hot water, for example, to wash dishes.

Now, it might not be very energy efficient to start taking 45-minute showers, but, it is possible. Homes with large soaker-style tubs or indoor jet-style tubs would benefit from a tankless water heater because after filling such a large tub, there will still be hot water left over for other household uses. With a traditional hot water tank, users would have to wait for the hot water tank to recover and refill before enjoying the comfort of hot water again.

Tankless water heaters work more efficiently to allow hot water to stay hot at all of the open water sources. The always-hot technology works so that when there is more demand, the water flow is slightly reduced to ensure that it stays hot for all users. Most would agree that whether at a sink faucet or in the shower, it is better to maintain a consistent temperature instead of the highest water pressure. Plus, if you have already installed eco-friendly showerheads or kitchen or bathroom faucets, you already understand that low-flow water pressure is what helps save you money on your water bill and helps the environment.


Differences Between Tankless Water Heaters and Traditional Water Heaters?

Best Tankless Water HeaterWith traditional water heater tanks, anywhere from 20 to 100 gallons of water is kept at a high water temperature. But, all good things must come to an end, and the stored water within can run out. We’ve all been privy to other household members using up all of the hot water before we could get a hot shower or bath, and been forced to rush through using lukewarm, and then eventually, cold water.

Traditional water heater tanks are large, often 4–6-feet tall drums. These units monitor the temperature of the water, constantly heating it to your required temperature so it is available on demand. Hot water is drawn to all areas of the home, from the clothes washer and dishwasher to hot water taps and showers. The price of a traditional water heater tank is fairly stable, ranging from a few hundred dollars to maybe $750 on the high end. Traditional water heater tanks have been around for over 100 years. While their design has been improved, they do usually require users to insulate the units to try and keep heat and energy loss at a minimum.

One of the most common reasons consumers choose to go with a tankless water heater is because they do not want to pay to heat water that sits in a tank that they are not going to use. It is simply wasteful. Thus, the on-demand tankless water heater appeals to those who want to heat as needed.

Tankless water heaters are also very compact, allowing for significant space savings for the consumer. If you need to use your typical utility space for storage as well, it might be worth looking into a tankless water heater to save that space. Or, if your utility area is on the same floor level as your living space, you might be concerned about the possibility of a water heater tank leaking. If you have heirloom or expensive furniture, antiques, or paper items at floor level, water damage might be a worry for you.

In a small footprint, these tankless water heaters can power a lot! It might be worthwhile for those with a very small space to consider a tankless water heater for their hot water needs. For instance, if you have a small apartment or loft-style space, and you are responsible for your hot water, a tankless heater might be for you. Another consideration is if you travel often, you will not be paying for a tank to constantly heat water that you are not using.

Tankless water heaters only turn on when hot water is demanded. While they are running, they draw a significant amount of power, whether it’s electricity or natural gas or propane-powered. But, once the hot water is turned off, the unit powers down as well. Tankless water heaters also range from a few hundred dollars for the smallest units or point-of-use heaters to over $1,000 for some of the largest units.

The most significant price difference between hot water tanks and tankless water heaters comes in the installation costs. But, if you consider the longevity of tankless water heaters lasting 15-20 years versus traditional water heater tanks having to be replaced maybe 2-3 times in that span, the costs differences do not seem as vast.


Gas vs Electric Tankless Water Heaters

Gas vs Electric Tankless Water HeatersTankless water heaters vary greatly in price based on electric versus gas models, and the size and output demanded. Typically, electric models are cheaper than gas units. Outdoor gas units are more expensive than indoor gas-powered tankless heaters (but you also have to factor in the venting requirements of the indoor gas unit into the price). Point-of-use heaters, like the smaller electric units on our list, are the cheapest because of their small size and GPM flow rate. Costs can range from a few hundred dollars cheaper than the most common water heater tank to almost double the price.

If your home is already set up with gas lines for a traditional water tank, then you should be able to substitute it for a gas tankless water heater. Be sure to check your existing gas lines to make sure they match the required size for the new tankless water heater. Another thing to consider is that there is adequate wall space to mount a new tankless water heater near your current gas lines.

For an electric unit, the main consideration is that your have the appropriate space in your electrical panel for the necessary hard wiring. Wiring a new, larger-capacity panel can run almost $1,000 or more in parts and labor costs. First, consult the electric specifications or installation manual of your electric tankless water heater before you buy one to make sure you have the proper space.

The big drawback of electric tankless water heaters is the significant electrical needs of the heater. If you have an older home, your electrical panel might not have enough capacity to run the heater. Or, if you have other large appliances that are already drawing a large load (like a hot tub), you might not be able to dedicate the necessary ampage for the tankless heater. If you live in a region with high electricity costs, it might be worth looking into a gas-powered tankless water heater to see if those savings would be more beneficial for you.

The cost of the electrical wiring and parts (if not included with the unit from the manufacturer), and the copper piping and fittings to refit to your new tankless heater could cost anywhere from $200 to $300. If you are using a professional plumber to install the unit, you also have to factor in labor costs. When you add all of these factors up, the total could be close to the cost of a more expensive gas-powered unit.

For gas-powered units, all manufacturers have very specific venting requirements to ensure proper air circulation for indoor units. Some tankless water heaters require expensive stainless steel venting to prevent corrosion. Others give options of stainless steel or cheaper PVC piping. You also have to consider the rerouting of the gas lines to hook up to the heating elements, as well as the wiring requirements.

Most indoor units require a condensation drain for the vent, so be sure that there is a drain nearby. Labor costs for installation might be high for indoor units, considering the venting required. Gas-powered units require a significant amount of oxygen to mix with the gas for proper combustion. Outdoor units use the natural airflow under the heater for proper function and venting. If you choose an outdoor unit and live in a moderate or cold climate, be sure to use short water lines and insulate them to prevent freezing and energy loss.

Something to consider is that while tankless heaters might have a higher price tag initially, their cost might average out based on their lifespan. Consider the longevity of tankless water heaters—most can more than double the lifespan of typical water heater tanks. Be sure to properly maintain all of the functional parts of your unit (some require de-scaling or vinegar rinses periodically throughout the year) to ensure that it lasts as long as possible for you. You might also be able to install a filter on the water source to limit mineral deposits in the heating unit, prolonging the heater’s life. Depending on the brand, some tankless water heater units can last up to 20 years.


How to Install a Tankless Water Heater?

How to Install a Tankless Water HeaterOne important consideration when talking about price is the installation costs of a new tankless water heater. If you are switching to an electric model, there can be significant power needs for the new unit, so a circuit breaker panel upgrade may be necessary. We’ve also discussed the important venting requirements for a gas-powered unit. Some will argue that installing an outdoor unit (which is common in many areas around the world) will save you the worry of gas leaking indoors. These installation factors can affect your budget for the switch to a tankless model.

Water heater installation can be done by an experienced DIY home installer, but the electrical wiring or gas line work can be difficult or even dangerous if done improperly. You do not want to deal with gas exhaust leaking from your venting. From fitting the piping properly to following very specific vent routing, gas venting can be tricky.

Please take care to be meticulous and follow all instruction manuals if you attempt installation without a professional license. Ask for support by calling your water heater manufacturer—they are there to help and are the most qualified to answer any questions you may have. Overall, if you are not comfortable in your skills, hire a professional who installs units daily. They have the experience to know exactly where the problems may lie and how to fix them quickly. Moreover, a professional installation will usually seal your manufacturer’s warranty.

Be sure to check your manual before you attempt a DIY install, because it might void your warranty rights. Although, if you install the unit properly yourself, you might save enough money on the installation labor costs to average out the cost of a new unit (thus nullifying the need for the tankless heater warranty). Be sure to weigh up all of the price factors before you choose—we want you to have all of the facts before you decide.


What Size of Tankless Water Heater Should I Go For?

When looking for a good tankless water heater, determining the proper size for your home is the most important step. Actually, there is no such thing as buying too big of a tankless water heater. In fact, if you oversize, some electric units allow you to hardwire only the number of heating elements that you think your home will demand. It is always possible to go back and hardwire more heating elements if your water needs change. But, on the flip side, if you buy a small tankless water heater and your water needs are too great for the unit, your only option is to buy a secondary or different, bigger unit. That would likely cause some annoyance, and many users who are frustrated with their tankless water heater have probably purchased the wrong size.

For the most part, the more hot water taps or demands your home has, the bigger the unit you should purchase. This will make sure that no matter how many showers or faucets you are running, they will all have hot water at an even water pressure. Most of the tankless water heaters work so that if you have multiple units that demand hot water  that are open at the same time, the water pressure will drop and spread out so that everyone can have hot water simultaneously.

If you are in a warmer, more temperate climate, it will take less energy to warm up your cold water intake. Therefore, you would likely be able to choose one of the smaller capacity tankless heaters and have no problems with water pressure. Also, if you have one or two bathrooms or a family size of one to three people, your home would probably run fairly well on a smaller tankless water heater.

But if you live in a cold northern climate, your cold water intake temperature is pretty low and will have to use more energy (whether electricity or gas) to heat up the water. For a larger home of 2,000 square feet or more, three or more bathrooms, or four or more occupants, you would probably want a larger unit, too. It would probably be better for your home to use a larger electric or gas-powered unit. Although outdoor gas units are made to withstand the elements, it’s likely a better choice to look at indoor gas heaters, so you don’t have to worry about the possibility of pipes freezing.

There are multiple ways you can decide how much water your home uses. Online calculators or your latest energy bill are two good places to start. Once you have determined that average, you can make an educated choice about which tankless water heater will give you the GPM (gallons per minute) that your faucets, showers, and appliances will need. Most manufacturer websites will also give you a very close estimate of your water input temperature in your area of the country. You can then decide how much of a water temperature rise you will need for your home.

Interestingly, while your hot water demands might not change if you switch to a tankless water heater, your home occupants might become prone to using more hot water if they think that the unit is supplying a seemingly endless supply of hot water. Let’s say you have teenagers in your home, for example. It’s baffling how much time teens can spend in the shower. Your energy bills might benefit from a tankless system.


Do I Need to De-Scale Your Tankless Water Heater?

Do I Need to De-Scale Your Tankless Water HeaterWhether you have a tankless water heater or a traditional water heater tank, the minerals within your water will cause deposits. What region of the country you live in will affect the percentage of minerals in your water. Those with higher percentages will have harder water, and those with lower percentages are said to have soft water.

A buildup of scale, lime, or rust can coat the heating element or your water pipes and can cause up to a 30 percent reduction in energy efficiency. If you have already decided to use a tankless water heater, then you have researched and realized the importance of appliance efficiency. For it to function at its best, your tankless water heater cannot simply be installed and forgotten about. More than anything, tankless water heater manufacturers want your unit to function properly and as expected.

The heating element of a tankless water heater is usually made of copper and is sensitive to mineral buildup or scale. In order to keep your tankless heater functioning at its most efficient, most manufacturers will recommend an annual vinegar rinse, or de-scaling to remove deposits. If you do not de-scale the unit, you run the risk of buildup, which forces your heating element to work harder and use more energy. Without regular maintenance, mineral buildup can cause the unit to fail.

Studies show that 80% of homeowners do not do any kind of appliance maintenance. Think of your appliances (and thus your tankless water heater) like you would your car—you would not expect it to run at its peak performance without regular maintenance and upkeep. More than anything else, regular maintenance is key to performance. Another good prevention option tankless water heater owners often employ is to use a premium water filter on the cold water pipe intake. This filter removes many deposits from the water before it even has the chance to enter (or harm) the tankless water heater.


Energy Savings and Tankless Water Heater Size

If you have been researching tankless water heaters, then you likely know that the typical hot water heater in the U.S. is the second-largest energy drainer in the home. Usually the standard per-year costs range from $500 to $800, based on energy costs in your part of the country. Other areas of the world, such as parts of Europe and Japan, have been using tankless water heaters for quite some time, but their popularity in the U.S. has been less than stellar until more recently. There are quite a few U.S.-based water heater manufacturers, and the cheaper price of conventional water heater tanks has likely been a factor in sales. More often, as consumers have more global access to products, support, and information, homeowners are willing to try tankless heaters to save energy.

If you are already an eco-conscious consumer who cares about how your choices affect the Earth’s longevity, then saving energy and utilizing water efficiently are already important to you. Consider lightbulb usage and the changes that have been made in that industry. From low-flow showerheads to reduced-flush toilets and water faucets, there are many ways we can save water and associated energy around the home. Employing smart water-saving habits is not only important to conserve resources, but also to reduce water bills.

It has been estimated that tankless water heaters can be 24-34% more efficient than typical storage water heaters, and those are conservative estimates. Tankless water heaters ensure that your water is only heated when you need it at the exit point, as opposed to traditional water heater tanks that store gallons of heated water (and waste a percentage of that energy) to be ready when needed. It’s also possible that water consumption will drop because taps won’t run at their max flow until the water is hot enough to use.

Not only will most users save over $100 a year in natural gas or electric energy costs, there will also be a reduction in carbon dioxide emissions. You might think that it’s silly to discuss carbon dioxide, but studies have shown that electric water heater tanks produce about 3/4 of the average automobile’s CO2 every year. Reducing greenhouse gases like carbon dioxide is an important step to keep our Earth in its best shape.


Tankless Water Heater Comparison Chart

Water HeaterPower SourceWeightWarrantyRating
Ecosmart ECO 36Corded-electric 18.35 pounds Limited Lifetime 8
Rinnai RUC98iNGas-powered82 pounds Limited 12-year on heat exchanger9
Takagi T-KJr2-IN-NGGas-powered37 pounds 10 year heat exchanger 8
Rinnai RL Series HE+Gas-powered44.3 pounds 12-Year Heat Exchanger9
Noritz NRC66DVNGGas-powered39 pounds 12 Year Heat Exchanger9
Titan N-270Corded-electric 10 pounds Manufacturers6
Ariston GL4SCorded-electric 23.1 pounds 6-year warranty8
Takagi T-H3-DV-NGas-powered59 pounds Manufacturers8
Rheem RTG-95XLNGas-powered54 pounds Manufacturers8



You should thoroughly consider your average water needs and balance that with price considerations to decide if a tankless water heater is in your future. One benefit of a tankless water heater is the technology gives you exactly what every busy household needs—a perfect supply of hot water that will not turn cold after five minutes, or after two or three other people have already used it. While in the past you might have to wait for a hot water tank to refill over the course of an hour, that is no longer the case.

For those times when you oversleep and need to get ready for work quickly, you can depend on the hot water right away for your morning shower. A young family with messy children definitely washes more laundry and takes more baths—a tankless system will be a parent’s best friend in such a household.

The future is here—you demand hot water, and it is available at the tap almost instantly. It’s quite fascinating to consider what the next innovation will be.

After reading our tankless water heater reviews, we hope you have enough information to make an informed choice. All of the options for tankless water heaters can be overwhelming. Do not hesitate to call and ask for a recommendation for your home from a manufacturer or even a local plumber. It is also in the manufacturer’s best interests to give you an idea of which tankless water heater model is the best for you, because you will be a happy customer and you will get just the right fit for your home. Most call centers and plumbers are happy to help, and would rather you ask sizing questions up front instead of buying a unit and finding out that it is the wrong size for your household needs.

While we hope that you will continue to find other ways to reduce your water and energy usage in your home, we believe that investing in a good tankless water heater is a significant step in the right direction.