Best Gas Hot Water Heaters
Review & Buying Guide
(updated 2018)

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The best gas hot water heaters are high-efficient, high performing and environment-friendly systems, great choice for the homeowners that are looking to buy a brand new or upgrade an existing water heater. Even if you already have an electric unit, you might want to switch to gas, because of all the benefits and savings natural gas and propane-powered water heating devices bring.

Let's see what these benefits are, how gas hot water heaters compare to electric, top-selling brands, prices and where to shop for the deal.

This review and provided links are about gas water heating in residential homes, powered by propane and natural gas, and are providing tips for buying, covering both storage tank-type and tankless models. The articles also include reviews of the most popular manufacturers and models, installation, and maintenance tips, the most common problems, and help with the troubleshooting.

Selecting a gas hot water heater - Things to consider

Choose a fuel source

Gas hot water heaters are designed to use both natural gas and liquid propane - LP. Most of the built and sold water heaters are factory set to use natural gas as it is widely used and cheaper than propane.

To run propane water heaters, you need liquid propane (LP) storage tank and regular fuel delivery. The performance is similar to natural gas units.

When comparing natural gas vs. propane, it is worth mentioning that the energy factor (EF), is almost the same for most brands of gas heaters, both heating water fast.

Choose a type

There are two types you can choose from; storage tank type and tankless, advanced with and conventional without condensing technology.


Tank type water heaterTank-type

Tank-type water heaters are designed with the water storage tanks that have capacity from as little as a few gallons to over 100 - for residential homes. Hot water is always ready and available. The advantage over tankless type is the lower cost and simpler design, so less prone to failures. Best selling models utilize condensing technology, such as this Vertex model from AO Smith.

Recommended 50-gal models to Buy


Navien tankless water heaterTankless

Tankless does not store hot water but heat water as needed - on demand. Hot water is not seating at the bottom of the unit but is always delivered fresh. The greatest advantages over the tank-type are small design, advanced technology, longer life, energy savings, and flexible installation. Savings are even higher if the condensing units are chosen, which also gets lower energy consumption and better environmental protection. Good examples are those below, found as the best selling models.

Best selling gas powered tankless type models

Determine the size you need

This is an important one because a properly sized water heater will provide enough hot water for a home, resulting in increased comfort, efficiency and savings.

Storage tank-type gas hot water heaters are usually installed in a designated room, standing on the floor, while tankless, because of its small size and flexible venting options, almost anywhere, but mainly on the wall.

The most popular models are those with the tank capacity of 40, 50 and 60 gallons, as they can produce enough hot water for families of four, and homes with up to 2 baths, yet still being affordable. For the same family size, tankless water heaters with the flow rate of 8 gallons per minute or more will do the same work.

Select the best venting option

Other important factors to consider when looking for gas hot water heaters to buy, install or troubleshoot, are the options you have for the efficient and cost-effective venting.

When the gas water heater is running, it requires fresh air for combustion and ignition, and it can be used either from indoors or from the outside. It is also vital to safely remove products of combustion/flue gases outside, using the house chimney or provided vents.

There are several types of venting systems one should consider:

  • A conventional, atmospheric vent is using the chimney.
  • Direct vent, no chimney and blower needed, it vents directly out through the wall by using the provided vents.
  • Power vent is like the direct vent but with the help of the electrical power vent - blower.

Which gas water heater to buy?

If looking to buy the best tank-type gas heater, check out AO Smith GDHE-50-NG Vertex 100 or Polaris Water Heater, both with an ultra high energy efficiency of 96% making it the most energy-efficient models on the market. The first-hour rate on both units is very high, delivering hot water fast and when needed.

If looking for the best tankless, the recommendation is to buy one of the condensing units, such as Navien, Rinnai or Noritz, as they are known for ultra-efficient water heating, fast hot water delivery when needed and in endless supply.

Gas versus electric water heaters

  • Heating with gas is two times faster than using electricity, so more hot water is available during the peak hours.
  • Higher recovery rate. The 50-gallon gas hot water heater has the average recovery rate of 80-90 GPH while electric 50-gallon size has the recovery rate of approximately 60 GPH.
  • It costs less to operate than the electric units.
  • They are high-efficient by design.
  • There is a variety of products, from tank heaters to tankless and combination of gas-fired burners and tank type heaters.
  • Ultra efficient, condensing models are available.

Money saving tip: If gas hot water heaters are expensive to buy, renting one is always an option. Renting a water heater is convenient and gives you peace of mind, so if anything goes wrong with the unit, most parts and service are covered.

If planning to switch from an existing heating system to a new one, using natural gas or propane, consider next:

  • Converting to the natural gas hot water heater is easy.
  • If there is no chimney, direct or power vented heaters are your best bet.
  • If the chimney already exists, it has to be checked by a professional, and if it is needed, perform cleaning or resizing. Other options include using direct or power vent system which does not require a chimney.
  • It is also straightforward to replace an existing and old natural gas water heater with a newer one, but first, check the venting options in a home.
  • Older heaters are less energy efficient.

Main parts

  • Water tank to store water.
  • Glass lining for metal tank protection against corrosion.
  • Foam insulation - thicker better.
  • Draft hood for flue tube installation.
  • Flue tube to remove the products of combustion out.
  • Anode rod for corrosion protection. Some models are equipped with the stainless steel tank, so no anode rods are installed.
  • Dip tube for bringing the cold water inside the tank.
  • Drain valve for draining water during maintenance (for example).
  • Gas burner.
  • Gas combustion chamber.
  • Thermocouple safety element.
  • Pilot light or electrode for igniting the gas.
  • Gas valve.
  • The electric blower on power units to remove the gases out.
  • TPR Valve (Temperature and Pressure Relief Valve) safety element, protects from the excessive temperature and pressure.
  • Thermostat to control the temperature of hot water.

How tank type heater works

Once the hot water tap is open, hot water from the top of the tank starts running through the hot water outlet to the faucet or shower. At the same time, cold water enters from the bottom through the dip tube.

The thermostat senses the cooler water and turns on the gas at the gas valve and the burner that is mounted at the base of the tank. Thermocouple, as a safety element, sends the signal to the gas valve to open - only if there is a presence of a pilot flame to lit the gas. Once the flame is established, water is heated, and the products of combustion from the combustion chamber are removed through the flue vents out.

Related articles

Best models
Top 50-gal models
Natural gas
Propane gas
Direct vent
Power vent
Gas water heaters vs. heat pumps

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