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Best tankless water heaters in 2017-2018

small-heat-logoDid you know that approximately 1 out of 13 water heaters gets changed every year? The era of energy efficiency is here, and water heaters are among the first that need to be changed. The technology that allows us to heat the water has improved dramatically over the last years. Qualified entities such as ENERGY STAR have taken a stand into promoting and sustaining cost-effective machines.

Before I dip into reviews, comparison charts, guides and related, I would really like to give you some numbers on this industry field, so you’ll have a good grasp on what’s going on lately in the plumbing area:

  1. Water heating represents the second largest energy consumption (in domestic use), first being space heating/cooling. Approximately 17% of the residential power consumption goes into heating water. An average US household pays $200-$600 per year for this service.
  2. 99.5% of US households have at least a water heater, and most of them are fairly old (30%). More than 27 million households have water heaters older than 10 years, which is the average functional life of this type of appliance.
  3. Each year, 8% of US households replace their water heaters. Furthermore, around 1.2 to 2 million units are installed in new houses. That means around 9 million new water heaters are annually bought and used by Americans.
  4. Many of the water heaters sold today meet the regulations imposed by the Federal standards back in 2004, almost 15 years ago. ENERGY STAR qualified water heater units may consume up to 55% less, thus saving you up to $300/year. Although they’re a bit more expensive, they will most likely return the investment in time. There are also government incentives for buying ENERGY STAR qualified units in some parts of our country.

Types of water heaters

Considering the source of energy, there are basically 2 types of water heaters: with gas and electrical. Around 50% of US households use gas water heaters. These are mostly used in the West coast, Midwest and Middle Atlantic:

Prelevance of gas water heaters

Almost all the rest is served by electric water heaters (40%). These are used in the East South Central, South Atlantic and in the Pacific Northwest. There are other types of sources which are rapidly growing: fuel based (oil), propane, wood and last but certainly not least, solar.

My rating system

Unlike any other bloggers/handymen out there, I have a strict system of rating water heaters (I give them grades between 0 and 100), based on several features and characteristics, such as:

  • Controls (temperature control, LED indicators, digital or analog)
  • Wattage (power consumption)
  • Flow rate (how much hot water it produces)
  • Certification
  • Dimensions and weight
  • Warranty
  • Reliability
  • Accessories (i.e. a shower head, timers, thermostats, additional heating elements)
  • Special features (how easy it can be installed, used and serviced)
  • Price

I also differentiate between electric and gas, with tank or tankless water heaters, so I compensate the values to reach a common ground.

Brands and Manufacturers

There are several well known producers of water heaters. Among the most popular I may count A.O. Smith, Bradford White, Rheem, Ecosmart, Eccotemp, Reliance and Bosch. Others less known are Noritz, Stiebel Eltron, Atwood, PowerStar, Ariston or Water Worker. A.O. Smith, Rheem and Bradford White manufacture more than 2 thirds of the residential water heaters. These are old companies with a lot of history behind. Solar water heater kit are just starting to gain market, and are produced by smaller companies such as Heliatos or Milliard.

The distribution chain is a funny business. The main actors are big retailers (Lowes, Walmart, Sears, Home Depot and so on), specialized distributors and plumbers. The wholesalers and distributors sell about half, the other half being sold by retailers. Plumbers buy most of these for resale purposes. This is what I can’t understand: why homeowners, builders and all the others don’t just buy their own water heaters, instead of paying extra to plumbers? Plumbers make in fact about 20% of their business just from selling new water heater units. They work independently and usually care more about the price, than about the efficiency of the unit. Almost 70% of these water heaters are then installed by homeowners themselves, and only 30% still relay on plumbers’ help.

The water heaters are usually replaced for 3 main reasons:

  1. the previous unit dies completely
  2. the efficiency of the unit drop bellow a certain threshold
  3. the homeowners renew their water heaters after the expected lifetime of the previous units (planned replacement).

Here are the main features of the most used types of water heaters:

  • Common Electric Tankless
  • High-Efficiency Gas Storage
  • Gas Tankless
  •  Gas Condensing
  •  Solar
  •  Heat Pump
Innovations – Flow-sensor-activated heating mechanism, no standby losses, no venting required (no gas)

Energy consumption – 4-5000 kWh/year

Advantages – Inexpensive, easy to install and upgrade

Disadvantages – Relatively high operating costs

Typical installed costs (equipment + installation) – $700

Innovations – Good insulation, effective heat traps, low burner waste

Energy consumption – 240 therms/year

Advantages – Inexpensive, easy to install and upgrade

Disadvantages – High operating costs

Typical installed costs (equipment + installation) – $1300

Innovations – Flow-sensor-activated heating mechanism, no standby losses, good venting

Energy consumption – 180 therms/year

Advantages – Continuous delivery of hot water, requires less space

Disadvantages – High installation costs

Typical installed costs (equipment + installation) – $2000

Innovations – Higher yield, with more heat captured from combustion

Energy consumption – 190 therms/year

Advantages – Low consumption

Disadvantages – High installation costs: many require powered vents and condensate drains

Typical installed costs (equipment + installation) – $2200

Innovations – Uses solar energy

Energy consumption – 130 therms/year, 2400 kWh/year

Advantages – Very low consumption

Disadvantages – Higher cost, more frequent maintenance

Typical installed costs (equipment + installation) – $3200

Innovations – Moves heat from air to the water

Energy consumption – 2,195 kWh/year

Advantages – Low consumption

Disadvantages – Complex installation, requires a condensate drain and periodic filter cleaning

Typical installed costs (equipment + installation) – $1800

As you can see, tankless is usually better in terms of initial cost, maintenance and future replacements/upgrades. That is why I focus my advice on these types of water heaters. However, occasionally I will review some old fashioned models, and I will definitely provide guides and advice on both types. You never know when these might come in handy.

Best electric tankless water heater

Here are my favorite electric tankless water heaters:

Ecosmart ECO 18 / 24 / 27 / 36 with Patented Self Modulating Technology Rheem RTE 3 / 7 / 9 / 13 / 18 / 27 Electric Tankless Water Heater Stiebel Eltron Tempra 15 / 20 / 24 / 29 / 36 Plus Electric Tankless Water Heater
Limited lifetime warranty 10-year warranty (1 year on parts) 3-year limited warranty
95/100 91/100 96/100
2.5 GPM / 3 GPM / 3 GPM / 3.5 GPM 1.5 GMP / 2.5 GPM / 3 GPM / 3.5 GPM / 5 GPM / 5 GPM 4.5 GPM / 8 GPM / 8 GPM / 8 GPM / 8 GPM
Digital temperature control, self modulating technology Analog controls Digital temperature control, advanced flow control
$359.00 / Check price / Check price / Check price Check price / - / Check price / Check price / Check price / Check price $667.58 / Check price / Check price / Check price / Check price

Best indoor gas tankless water heater

Here is my top 3 for the indoor gas tankless water heaters:

Rheem RTG-64DVLN / RTG-84DVLN / RTGH-95DVLN Low NOx Direct Vent Tankless Natural Gas Water Heater Rinnai RU98IN 9.8 GPM Indoor Ultra-NOx Condensing Tankless Natural Gas Water Heater Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater
12-year warranty (5 years on parts) 12-year warranty (5 years on parts) 15-year warranty (5 years on parts)
92/100 96/100 97/100
6.4 GPM / 8.4 GPM / 9.5 GPM 9.8 GPM 10 GPM
Direct Vent Indoor, UMC-117 remote control, 10 ft. of thermostat wire Ultra-Efficient, Condensing Technology Computerized safety features, no pilot light
$749.99 / Check price / Check price $2,233.38 $1,099.90

Best outdoor gas tankless water heater

Here are some of the best outdoor gas tankless water heaters:

Rheem RTG-64XLN / RTG-84XLN / RTG-95XLN Low NOx Outdoor Tankless Natural Gas Water Heater Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing Tankless Natural Gas Water Heater Eccotemp L10 High Capacity Outdoor Tankless Water Heater
10-year warranty (1 years on parts) 12-year warranty (5 years on parts) 1-year warranty
92/100 96/100 90/100
6.4 GPM / 8.4 GPM / 9.5 GPM 9.8 GPM 2.6 GPM
Low Nox Version, UMC-117 remote control, 10 ft. of thermostat wire Ultra-Efficient, Condensing Technology Automatic safety shutoff timer, 9′ gas regulator and hose, a stainless steel rain cap, a 1/2″ NPT
- / Check price / Check price $1,250.39 $229.00

Best solar water heater

While not exactly tankless per se (they are actually based on big tanks and usually use hybrid sources of energy), solar water heater kits are gaining popularity lately. Here are my top picks for solar water heaters:

Rheem RS47-21BP Solaraide Passive Solar Series 47-Gallon Storage Capacity Water Heating System Rheem RSG75-40BP SolPak Gas Assist Solar 75-Gallon Natural Gas Complete 4 Panel EZ-Connect Hybrid Solar Water Heater Kit
5-year limited warranty 6-year tank warranty, 10-year collector warranty, 2-year pump warranty No warranty
97/100 97/100 80/100
Check price Check price Check price

Final words

small-heat-logoI hope this site provides real usable information. If you spot an error, want to share some thoughts on the subject or need some help with your projects, don’t be afraid to comment. I love comments. I try to comment on other people’s blogs as much as I can. Comments are useful and feedback helps in making sites better.

Beth Cummings

Beth is a 30 years old handy-“woman” who likes to work hard on accessible DIY plumbing projects, specifically on installing, servicing and replacing water heaters. She also finds talking at third person about herself to be rather awkward.


  1. Thanx for informative site, wish I had come across it 14 months ago before I got con into installing Quietside (now Coaire) DPW120A. I was under impression from my limited research at the time it was a Takagi product. It worked fine till recently. Three service calls in a month, $700 later & DPW120A still not working?!? It’s an expense hardly worth savings on gas which i dont think has made much difference. I waited 3weeks without hot water service for a pump which Skky Radiant said would only take 2-3 days. Unit ran for 2days after Wayne (indie service tech) replaced another pump which he had already replaced 2months ago. Error code reads A5 same as last time, I switched unit off & on again & it ran for 5 days but now, switching off & on would only run unit for 3 minute & automatically shuts down again with same Error code A5. Sales & Installer claimed 24/7 service but has been ignoring my calls. I went on to Challenger site in Fortworth Texas only to discover faulty product with a safety recall since Nov/14 & no one from Skky Radiant, March Green, nor Challenger contacted me with any hazard warning. Had unit not broken down, i would not have stumble upon that information. Unit 1st broke down only 14 months after installation & with recent multiple repairs within 2months having never ending results, it’s time March Green, Skky Radiant & Challenger stand behind their products & take responsibility by replacing this overpriced landfill anchor with something that actually works. Any suggestions?

    • Its the water pump and the electronic panel. You could try to repair it, but in the end, you’ll end up replacing the unit. My recommendation: get a new one.

  2. Hello, thanks for the information given. I am wondering why you don’t mention the Ecosmart 11. I live alone and have a small house and believe it will be just enough for me. Please comment.


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