Best Tankless Water Heaters
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Before the invention of the modern water heater, people largely relied on water heated over a fire grate or stove to take a warm and comfortable bath. Then came the invention of the first water heaters in the mid-19th century. While the convenience of bathing in warm water minus all that hauling was still beyond the reach of the general populace, it was only a matter of time before many households in the country had a water heater of their own.

Conventional water heaters, however, are bulky and quite complicated to install. They are also notoriously inefficient when it comes to energy consumption, resulting in higher utility bills for many homeowners.

All that changed with the arrival of tankless water heaters. They are compact and easier to install. You can have hot water in an instant, and they are great if you’re looking to save on utility bills.

If you’ve decided to switch from a conventional water heater to a tankless one, then we’ve got you covered. We’ve curated some of the best tankless water heaters you can purchase online. Check out their pros and cons below, as well as some tips on how to choose the perfect on-demand water heater.

Rinnai V53DeP Tankless Hot Water Heater, 5.3 GPM, Propane, Outdoor Installation
  • Endless Hot Water: Our tankless hot water heaters let you enjoy unlimited hot water flow throughout the house with a compact and durable design that fits your home and lifestyle
  • Energy and Space Efficient Tankless Gas Water Heater: This small hot water heater conserves energy, only heating when necessary; Enhanced scale detection lessens possibility of serious, long-term damage to unit
  • Optimal Water Pressure: This tankless water heater offers a high-performance hot water flow rate up to 5.3 GPM for a powerful, constant stream that serves up to 4 appliances at once
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Guaranteed to Last: 10-, 5-, and 1-year residential factory warranty for heat exchanger, labor, and parts, respectively
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White, 20.2
  • CONTINUOUS FLOW – Advanced Flow Control patented technology invented by Stiebel Eltron, automatically maintains water temperature for constant comfort. It’ll reduce flow slightly if hot water demand exceeds capacity. Hot showers will never be interrupted again
  • SPACE & ENERGY SAVER – Its small, sleek white design saves space yet still provides endless hot water for your whole house, and no venting is required. Eco friendly unit saves energy with auto-modulation and the ability to electronically control water flow. Savings monitor even shows how much you save on energy costs
  • EASY OPERATION – Electronic switch activates the hot water heater and it’s noise free while in use. Has a digital temperature display and preset temperature and memory buttons, while the interior solid copper heating system does all the power work
  • TEMPRA 24 PLUS – This specific model is 24kW, 240V, requires a min recommended electric service of 150 A, and offers an output water temperature of 68° to 140°F. Check our guides below to compare features of our various Trend and Plus models, each available in different kW levels, Tempra Plus tankless water heaters can be set to limit the maximum hot water temperature to 109°F. This can be important in some installations to prevent the possibility of scalding.
  • WARRANTIES INCLUDED – Stiebel Eltron’s top-rated electric tankless water heaters perform with the highest standards for comfort and reliability. Our 7-Year Leakage and 3-Year Parts Warranties are included with purchase
Noritz NR50ODNG Outdoor Tankless Water Heater, max. 120,000 Btuh, 5.0 Gpm - Natural Gas
  • Endless hot water
  • Ideal for outdoor applications
  • High Efficiency
  • Low Nox
EcoSmart ECO 27 Tankless Water Heater, Electric, 27-kW - Quantity 1, 17 x 17 x 3.5
  • Endless on-Demand Hot Water; Consistent hot water when you need it that never runs out; Continuously monitored water temperature and controlled flow rates ensure efficiency and consistent performance within 1 degree of selected temperature
  • Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank heaters; may be installed on wall or at point of use; Dimensions 17 x 17 x 3.75 inches
  • Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only heats water when called unlike a tank heater that maintains water temperature even when not being used. Save up to 50% in water heating costs according to the Department of Energy
  • EcoSmart ECO 27 Sizing; Refer to the sizing map. Requires 3x40 AMP Double Pole Breaker, 27-kilowatt tankless electric water heater ideal for providing hot water for whole home applications; provides between 2.7 and 6.5 gallons-per-minute depending on the inlet water temperature; refer to the sizing guide to select the proper solution
  • Warranty and Certifications; Limited Lifetime Warranty on electronics, exchanger and element; UL-499 certified; ETL Listed
Rheem 18kW 240V Tankless Electric Water Heater, Gray
  • External digital thermostatic control with LED display (+/1 degree accuracy)
  • Most advanced self-modulation, adjust power to meet hot water demand
  • Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM
  • Simple installation – bottom 3/4 inch NPT water connections
  • Threaded for easy replacement, simple installation, digital temperature display
BLACK+DECKER Tankless Electric Water Heater 18kW 240 Volt 3.7GPM, Self-Modulating Multi-Application Unit for Small Homes or Apartments, Hot Water on Demand, Digital Temperature Display
  • Hot Water on Demand: Powerful 18kW heating system provides endless hot water with automatic water flow sensors. Ideal for entire home to receive instant and continuous hot water in seconds. Self-modulating unit allows you to set and maintain desired temperature in increments of 1℉. Easy-to-use and read digital temperature display.
  • Multi-Use Application: For commercial or residential use. Hot water tank designed for up to 3 simultaneous applications or a small apartment in hot climates. Ideal for bathrooms and kitchens.
  • Save Space & Money: Wall-mounting design allows you to install virtually anywhere - in a cabinet, closet, garage, basement. Save space with compact unit size. No bulky hot water tank needed; Save up to 50% on heating costs as water only heats when you need it.
  • Reliable & Durable: Extensive warranty of 7-year leakage-free coverage, 5-year heat exchanger, 2-year parts; Durable stainless steel, non-corrosive internal canisters and piping provide increased heating efficiency and life expectancy. Lead-free.
  • Easy Installation: Requires 2 x 40 amp single-phase double-pole breaker, 2 x8 AWG wire size and 240V; Standard 1/2 in. NPT (straight thread) fittings. Unit does not require gas lines or venting.
Takagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural Gas
  • 140,000 BTU. Voltage: AC 120V
  • 6.6 GPM max flow rate. Water connection location- bottom
  • 4-Inch category III stainless steel venting required
  • Inlet, outlet thermistors for constant temperature monitoring
  • Energy factor of 0.81-0.83

Tankless Hot Water Heater Buying Guide

Here are some of the aspects you have to consider before buying a tankless hot water heater.

Type of Fuel

There are two types of fuel used by tankless hot water heaters: gas and electricity. They both heat water, but they both have pros and cons that you need to consider before choosing the right unit for your home.

Electric tankless water heaters are easier to install compared to gas water heaters. They are more compact, and they do not require ventilation as gas water heaters do. Since they are more compact, they can be installed not only in the basement but also in closets and other unexpected areas in your house.

You have two fuel choices when it comes to gas-powered tankless water heaters, and these are natural gas and propane. Whether you choose natural gas or propane, know that gas tankless water heaters are a bit more complicated to install than their electric-powered counterparts. First, you have to check if your house’s existing gas lines and venting ducts are compatible with your chosen unit. Non-condensing gas water heaters, in particular, can take a little longer to install as they require a more complicated venting system.

Overall Cost

Initial Cost

When it comes to the initial cost, electric hot water heaters are the clear winner. As mentioned, they are more affordable than their gas counterparts as they are more compact and easier to install. Gas tankless water heaters, on the other hand, are bulkier and are more complicated to install, and these factors drive the initial cost higher.

best tankless water heater

Energy-Efficiency and Fuel Cost

Electric water heaters are more energy-efficient than gas-powered ones, thus allowing you to save more when it comes to fuel costs. In many areas around the country, natural gas and propane are often cheaper than electricity. But the price of gas on the market often fluctuates, while the price of electricity generally remains stable. If you want to save more on fuel, then it’s best to choose an electric tankless water heater instead.

Flow Rate

1.32 GPM. 3.7 GPM. 5.0 GPM. These numbers can be a real head-scratcher if you don’t know what they mean and you’re shopping for a new on-demand water heater. These numbers refer to the water heaters’ flow rate, which is measured by gallons per minute (GPM). Knowing your household’s flow rate is crucial if you want to purchase a tankless water heater with the right capacity.

Let’s say your showerhead has a maximum flow rate of 2.5 GPM, while your kitchen faucet has a flow rate of 1.8 GPM. Or let’s say you and your spouse have to use two different showers at the same time, and both showerheads have a flow rate of 1.8 GPM. In the first example, you have to have a tankless water heater with a flow rate of at least a 4.3 GPM to be able to use both the showerhead and kitchen faucet at the same time. The second example, on the other hand, calls for a tankless water heater with a minimum flow rate of 3.6 GPM.

best tankless water heater


Our choice for the best tankless water heater is the Rinnai Tankless Water Heater. Let’s take a look at why this particular water heater is a good choice for your home.

This Rinnai Tankless Water Heater is a compact and powerful gas-powered water heater. If natural gas is available in your area, then this is the ideal tankless water heater for you. But if natural gas is not available in your area or you just don’t want to use it, then you can hook it to a propane tank. Keep in mind, though, that this gas water heater is for outdoor use only, so you might need a local plumber to install it for you.

Its maximum flow rate is 5.3 GPM, making it ideal for larger households. Planning to use the kitchen sink while your child or your spouse is using the shower? Then this water heater won’t let you down. It is also quite energy-efficient for a gas water heater. It is Wi-Fi ready, and you can enable voice activation using an optional remote control Wi-Fi module.

There you have it. The best tankless water heater on the market. If it’s too pricey for you or if you want an electric tankless water heater instead, then be sure to check out the other options above.

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