The Best Gas Water Heaters for the Home

If you’re looking to upgrade or replace your gas water heater, you may want to discover the features offered with many of the best gas water heaters.

By James Fitzgerald | Updated Dec 22, 2020 5:39 PM

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Best Gas Water Heater

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Buying a new water heater used to be easier. With only the conventional tank-style heaters available, you used to have few options. Nowadays, advances in technology have led to the development of different types of water heaters, along with various electronic components and features that can make your purchase decision more challenging.

Since a hot water heater can be a substantial investment, it’s important that it will last for years to come. Read on to learn what factors to consider when looking for a new water heater, to see some of the highest-rated products spanning several different categories and to discover how to find the best gas water heater for your home.

  1. BEST OVERALL: Rinnai High Efficiency 6.5-GPM Tankless Water Heater
  2. RUNNER-UP: A.O. Smith Signature 40-Gallon Water Heater
  3. BEST BANG FOR THE BUCK: Sure Comfort 40-Gallon Natural Gas Tank Water Heater
  4. BEST TANKLESS: Rinnai High Efficiency 7.5 GPM Tankless Water Heater
  5. BEST COMBINATION: Rheem Prestige 9.9 GPM High Efficiency Combi Boiler
  6. BEST 50-GALLON: Rheem Performance 50-Gallon Tank Water Heater
Best Gas Water Heater

Photo: depositphotos.com

What to Consider When Choosing the Best Gas Water Heater

Although knowing that you need a gas-powered hot water heater somewhat narrows your search, there are still several other factors to consider when selecting the perfect one for your home. There are different types of gas water heaters with different installation and maintenance requirements, energy-efficiency ratings, storage capacities, and safety considerations. Take the following considerations into account when looking for the best hot water heater for your home’s specific needs.

Type

There are three primary types of residential gas water heaters: storage tank, tankless, and combination units.

Storage tank water heaters are the most common type. They consist of an insulated tank that uses a flame burner to warm the water stored inside and a thermostat that regulates the temperature of the water in the tank. The heated water stored in the tank supplies all the hot water to your home’s faucets and appliances. The primary disadvantage of these systems is that you need to wait for the tank to refill and reheat after the hot water in the tank is depleted from use, like after a long shower. This can take up to an hour.

Tankless water heaters don’t store a large reservoir of hot water but use a compact boiler that heats water only when hot water is needed. Also called on-demand water heaters, they are similar to running a hot water faucet or shower valve, which makes them significantly more energy-efficient. Since they don’t rely on preheating and storing a large reservoir of water, the risk of running out of hot water is less than with a storage tank heater. However, a tankless hot water heater might not keep up with an excessive demand for hot water if it doesn’t have sufficient output capacity. The other disadvantage of tankless systems is that they’re more expensive to purchase and install.

Combination water heaters, sometimes called combi boilers, combine a hot water heater and a central heating boiler into a single highly energy-efficient unit. They use energy to heat a single unit that’s responsible for both the home’s heating and hot water, instead of requiring energy to fuel two separate appliances. The primary disadvantage of these units is that they’re incredibly expensive to purchase and install and are only practical for homes that are heated with an existing boiler, not a furnace. Although they’re rarely seen in American residences, they’re popular in the United Kingdom, where they account for more than half the boilers installed in newly constructed residences. In the United States, they’re most often used in small apartment complexes.

Size and Capacity

The water-storage capacity of tankless and combination hot water heaters can range from 20 to 100 gallons, with the most common sizes being between 40 and 50 gallons. The general rule of thumb for determining your hot water needs is to add 10 gallons for each person in your household. A 40- to 50-gallon tank should be plenty for a four-person home.

A tankless water heater’s capacity is determined by the flow rate in gallons per minute (GPM). A home’s needed flow rate for a tankless water heater depends on the flow rate required by each of your hot water fixtures, including your kitchen and bathroom sinks, shower, and tub, and the number of people in your household. Each fixture requires a certain flow rate for optimal operation, and more people in your home means there is a higher likelihood that more than one fixture will be running simultaneously. Generally speaking, a household with fewer than four adults needs a tankless water heater with a flow rate of between only 3 and 5 GPM, while a household with more than four adults may need a heater with a flow rate between 6 and 10 GPM.

Combination boilers will have different sizes and capacities depending on the size of the existing boiler that you will be replacing. Therefore, it’s best to consult a professional installer when determining the size and capacity of your combi boiler.

Direct-Fired vs. Indirect-Fired

Storage tank water heaters can heat water through either a direct-fired or indirect-fired process. Direct-fired heaters have their own burner that heats the water in the tank directly. They have an open-flame burner integrated into the tank, so combustion gases need to be released through ventilation lines to the outside. Direct-fired heaters are the most common type since they’re typically more affordable and energy-efficient and can be installed in any home.

Indirect-fired heaters use a boiler that’s separate from the storage tank. They use heat transfer coils to transfer the heat from a separate boiler, typically the boiler used for the home’s central heating, to the water in the storage tank. Depending on the distance between the water tank and the boiler, they may be less energy-efficient. However, they require less maintenance since they don’t have a burner that can experience mechanical defects, or gas and ventilation lines that need to be periodically serviced. They also can be potentially more energy-efficient than direct-fired heaters since they passively utilize the heat generated from a boiler or furnace already running to heat your home. Indirect-fired heaters can only be installed in homes already equipped with compatible boilers and don’t require any ventilation since no combustion is taking place at the tank.

Energy Efficiency

The energy efficiency of a water heater refers to the amount of energy that is actually used to heat the water. This is an important factor to consider since water heaters are the third most energy-demanding appliance in most homes and can account for as much as a quarter of your monthly utility bill. Every new water heater comes with an Energy Factory (EF) efficiency rating that indicates the percentage of heat energy that’s used to heat the water. The EF factor is expressed as a ratio instead of a percentage, but an EF rating of 0.7 means that it converts 70 percent of the energy used into heat. Combination hot water heaters use the Annual Fuel Utilization Efficiency (AFUE) rating, which expresses the energy efficiency as a percentage and is the rating standard used for boilers.

Although gas water heaters are less efficient than electric water heaters, gas is usually considerably cheaper than electricity, which will likely translate to a reduced overall operating cost. Regardless of fuel source, tankless water heaters are much more efficient than storage tank peers and can reduce your monthly energy bill by up to 40 percent.

Safety

Hot water heaters are generally safe to use, but there are still some important safety considerations to keep in mind. Direct-fired hot water heaters require proper ventilation to allow the toxic and flammable combustion gases to escape to the outdoors. Proper temperature regulation of the water inside your tank also is important, and you don’t want the water getting too hot or too cold. Water temperatures that are too high, above 140 degrees Fahrenheit, can cause scalding burns on people exposed to the hot water. Water temperatures that are too low, below 120 degrees Fahrenheit, can cause bacterial growth and an increased risk of contracting Legionnaires’ disease.

Water temperatures inside a water tank in excess of 212 degrees can turn into steam, which will increase the pressure in the water tank and possibly cause an explosion. Fortunately, water heaters have temperature and pressure relief (T&P) valves to prevent this from happening by automatically relieving the tank’s internal pressure when a high enough pressure is reached. You should never attempt to relieve the T&P valve manually by yourself but should contact a professional plumber if you are concerned about your water heater’s temperature or pressure levels.

Installation

Installing hot water heaters can be an expensive and labor-intensive task that requires a considerable knowledge-base and skill set. As a result, it’s not a task that should be attempted as a DIY project but should be done by a professional plumber.

Installing a tankless water heater by yourself is especially discouraged since new gas and water supply lines often need to be installed. Installing a combination water heater also is a highly complicated procedure that should be reserved for professionals. Depending on where you live, the cost of installing a storage tank water heater can range from $800 to $1,300, installing a tankless water heater usually costs between $1,000 and $3,500, and the cost of installing a combination hot water heater can be between $3,500 and $8,000.

Maintenance

Unlike installation, a hot water heater can be easily maintained by the average DIYer. Regardless of the type of hot water heater you have, the primary maintenance consideration is the removal of mineral and sediment buildup. Mineral deposits will accumulate in your storage tank over time, causing corrosion that can reduce the energy efficiency and lifespan of your heater.

For storage tank heaters, it’s recommended to flush the tank every two years. This is done by shutting off the gas and water supply to the tank, attaching a hose to the drain valve at the bottom of the tank, running the hose outside, and then opening the tank’s drain valve until it’s completely flushed.

Tankless water heaters need to be flushed more often, usually once or twice a year since mineral deposits tend to accumulate more rapidly. Most tankless heaters have purge valves that are accessible under the tank’s lid that will accommodate a hose attachment so it can be flushed like a storage tank heater. You simply shut off the water and gas supply, hook your hose up, run your hose outside, and open the purge valves. It’s also recommended to rinse the heat exchanger with vinegar to remove accumulated mineral deposits from the coils.

Our Top Picks

Now that you know more about gas water heaters for the home, it’s time to start shopping. Keeping the above factors in mind, consider the following top-rated products in several categories.

Best Overall

Best Gas Water Heater Rinnai
Photo: lowes.com

One of the main disadvantages of many tankless hot water heaters is the cost of the unit, but Rinnai’s tankless unit is a powerful hot water heater at an affordable price. This tankless unit boasts an EF rating of 0.82 but still generates enough power to produce a 6.5 GPM flow rate that will bring continuous hot water to a four-person household. Although it will still be more expensive to install than a conventional storage-tank heater, its compact size offers a wider range of location options, and it won’t take up precious floor space in your home.

Runner-Up

Best Gas Water Heater Smith
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A.O. Smith’s 40-gallon hot water heater offers features similar to more expensive units but at a fraction of the price. It features a 40,000-BTU burner that can satisfy the hot water demands of a three- to four-person household and can deliver as much as 67 gallons in the first hour to avoid the hassle of running out of hot water when demand is high. It’s also equipped with an LED display for diagnostic reporting, push-button ignition, an electronic gas valve for precise temperature regulation, and safety features that prevent accidental fires from vapor ignition.

Best Bang For The Buck

Best Gas Water Heater Sure
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For an affordable hot water heater that doesn’t compromise on functionality, this 40-gallon water heater from Sure Comfort might be all you need to affordably replace your hot water heater. Although it’s not the most powerful unit on the list, the 34,000-BTU burner is plenty for a household of two to four people and delivers 67 gallons of hot water in the first hour of operation. Its tall and sleek design is made to make installation easier, which may even reduce the cost of installation.

Best Tankless

Best Gas Water Heater Rinnai75
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If you’re looking for an energy-efficient water heater that takes up the least amount of space, a tankless unit may be your best bet. Rinnai’s tankless water system has a high EF rating of 0.82 but is still powerful enough to generate a 7.5 GPM flow rate that is large enough to satisfy the hot water demands of a four-plus-person household. Since it only measures 23 inches high and 14 inches wide, it can be installed in out-of-the-way places like an attic, basement, and crawl space without taking up floor space like a conventional storage tank heater.

It also comes equipped with an integrated scale detection feature that monitors for mineral deposit and corrosion buildup so you can stay on top of maintenance and maximize the life of the unit. This tankless heater also is more affordable than many tankless systems but is still more expensive than storage tank models.

Best Combination

Best Gas Water Heater Rheem
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If you’re tired of wasting money to power a central heating boiler and hot water heater, you may be considering a combination hot water heater. This combi boiler from Rheem boasts a 9.9 GPM output capacity that can satisfy the hot water demands of a home with up to two and a half bathrooms while using the least amount of energy possible with an AFUE rating of 95 percent. It also features a room air intake vent to eliminate the need to install an intake vent to the outside, and the exhaust vents are compatible with PVC to further reduce installation expenses.

Best 50-Gallon

Best Gas Water Heater Rheem50
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For a no-frills storage hot water tank that offers enough power and storage capacity for a three- to five-person household, Rheem’s 50-gallon hot water heater might be just what you need. It features a 38,000-BTU burner that can deliver an impressive 85 gallons of water in the first hour. The tank’s narrow profile was designed for ease of installation in a variety of indoor spaces, so the unit’s affordable price point is complemented by a potentially reduced installation cost. However, its EF rating of 0.63 won’t save you as much money on your utility bill as other more efficient units.

FAQs About Gas Water Heaters

There’s a lot of information to digest when you’re considering a new water heater, so you might have many questions. The following answers to some of the most frequently asked questions may help.

Q. What are the disadvantages of tankless water heaters? 

Cost is the main disadvantage of tankless water heaters since the units are typically more expensive to purchase, and they’re also more expensive to install.

Q. Will a gas water heater keep the water warm in the entire house? 

If you purchased a gas water heater with a sufficient capacity to satisfy your home’s hot water demands, it should easily be able to keep the water warm in your entire house.

Q. Can I replace my own water heater? 

Unless you’re an experienced plumber, it’s generally recommended to hire a professional to install your new hot water heater.

Q. How long do gas water heaters last? 

Gas water heaters can last between eight and 20 years.