The Best Gas Water Heaters in 2021: Buying Guide & Reviews

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Best Gas Water Heaters 2021

A water heater is an essential investment but also an expensive one. If you’re looking for the newest and best gas water heater to upgrade your water heating system, it is crucial that you get it right.

Our buying guide will help you make the correct choice, and the review section has a number of excellent gas heaters ranging from light duty, portable heaters to residential-commercial grade ones.

Traditional Gas Heaters vs. Tankless Gas Heaters

There are two types of gas water heaters: traditional heaters (tank heaters) and tankless heaters (on-demand heaters.)

Traditional Heaters

In a traditional heater, the cold groundwater flows from the pipes and into a large, insulated water tank that is usually between twenty to eighty gallons. The cold water in the tank is heated up by a mechanism at the bottom, or on the inside, of the tank. In a gas-fired traditional heater, this mechanism is either a natural gas or propane burner depending on the model you chose.

Most households are designed to work with a traditional heater (unless you have a brand-new home or your house has been retrofitted for a tankless heater.) So installation, in most cases, is cheaper and easier than tankless heaters. 

Traditional heaters also have the advantage of being simpler than tankless heaters and tend to be more structurally robust, so they require less maintenance and are cheaper to maintain.

The flow rate of a traditional heater is technically unlimited and you can draw as much water as needed from any appliances as long as you don’t exceed its capacity.

 A notorious drawback in traditional heaters is standby heat loss. Even when you are not using hot water, the heater will still be on in order to keep the water warm for later use and this can increase monthly utility bills. The latest heaters, however, have tanks with thicker insulation to minimize heat loss.

Tankless Heaters

In a tankless heater, the water is directly heated up by the unit as it flows through, without the need for a water tank. When you turn on your showerhead, the heater automatically turns on, draws in cold water, and starts the heating process. A trade-off is a limited flow rate from a low of 1.25 gallons per minute (GPM) to as high as 11 GPM, even though the water supply is uninterrupted. 

Since the heater unit only operates when needed, tankless water heaters are also commonly referred to as on-demand heaters. They eliminate standby heat loss, so are more cost effective than traditional heaters. According to the U.S. Department of Energy, a tankless heater can be 8 to 14% more energy efficient for homes that use up to at least 86 gallons of water per day.

Tankless heaters also have a longer average lifespan. While traditional heaters only last about ten to fifteen years, tankless ones can last up to twenty years. Even then, manufacturers often have upgraded parts that can extend the product’s life cycle.

Despite their many advantages, however, tankless heaters cost a lot more in general and installation may require extensive retrofitting. 

How to Select the Best Gas Water Heater

Fuel Type

Gas heaters either burn natural gas or propane. There are important differences between these fuels: 

Propane is more energy efficient. One cubic foot of propane nets about 2,516 BTUs of energy, while natural gas gets only 1,030 BTUs.

Natural gas is more cost effective. Natural gas costs about $9.26 per 1,000 cubic feet (as of March, 2020). That’s about one million BTUs of energy equal to 11.2 gallons of propane. 1-gallon of propane is around $2, so the cost is more than double.

Propane is an environmentally friendly energy source. It is considered as a green fuel and releases much lower levels of greenhouse gases when burned than natural gas due to its low carbon content. It has also been approved by the EPA as a clean alternative fuel.

  • In conclusion, propane is a greener, more efficient fuel type but can be more costly to use. On the other hand, natural gas is the best choice in terms of cost savings.


When considering size, it’s important to first look at flow rate and temperature rise:

Flow Rate

Flow rate is the volume of hot water produced in a period of time. With a tankless heater, flow rate is popularly measured in gallons per minute (GPM). For example, a 2 GPM tankless heater can produce two gallons of hot water per minute.

The exact flow rate of a tank heater is affected by various external factors such as tank capacity, burner size, and fuel source. However, two parameters that can be used to make a good estimation are the first hour rating and the recovery rate or recovery time. 

First hour rating (FHR) refers to the amount of hot water (in gallons) the heater can supply per hour from a full tank. For example, a traditional heater with a FHR of 79 gallons can give 79 gallons of hot water per hour before the tank runs dry.

Vice versa, recovery rate indicates how much hot water the heater can produce once it is emptied. For example, if a heater has a recovery rate of 40 GPH (gallons per hour) and has a 40 gallon tank, it would take the heater about an hour to top the tank up from an empty state.

The first step to selecting the best tank size is to list all appliances that draw hot water and calculate their combined flow rate: 

ApplianceAverage Flow Rate
Tub4.0 GPM
Shower1.5 – 2.0 GPM (depending on efficiency)
Washing Machine2.0 GPM
Dishwasher1.5 GPM
Sink1.5 GPM

You should also take into account people’s habits. At which time of the day does water usage peak? What appliances and how many are used simultaneously during peak hour?

The peak hour demand will act as the baseline for you to size your heater. The U.S. Department of Energy suggests that the best heater should match within one to two gallons of your peak hour demand

Temperature Rise (ΔT)

Temperature rise, or ΔT, refers to the difference in temperature between the inflowing groundwater and the temperature the heater is set to. For example, with a groundwater temperature of 57°F and a set temperature of 110°F, the ΔT would be 53°F.

ΔT is vital to consider if you live in cold regions with groundwater temperature close to freezing. Because your heater may have to work harder to raise it to reach the set temperature, the unit’s flow rate can suffer. 

The greater ΔT is, the less effective your water heater.

Energy Efficiency Rating

The energy efficiency of a water heater can either be denoted by the Energy Factor (EF) or Uniform Energy Factor (UEF). 

EF is an older measurement that’s gradually being phased out and being replaced by UEF. In spite of this, EF is still relevant because many manufacturers are still using the old standard for their heaters.

The math associated with measuring EF and UEF is complicated. Fortunately, you can distinguish a high-efficiency heater from a low-efficiency one using the Energy Star label.

For a heater to be Energy Star qualified, it must first pass a strict battery of tests administered by the U.S. Environmental Protection Agency (EPA). 

Here are all of the criteria that traditional gas heaters must meet for an Energy Star rating:

Note that “medium usage” and “heavy usage” refers to the daily hot water draw of the heaters. Medium usage heaters have a daily draw of roughly 55 gallons and heavy usage heaters have a daily draw of 84 gallons.

UEF for ≤ 55 gallonsMedium Usage UEF ≥ 0.64
UEF for ≤ 55 gallonsHeavy Usage UEF ≥ 0.68
First Hour Rating≥ 67 GPH at 135°F outlet temperature

And here is the table of criteria for tankless gas heaters:

UEFUEF ≥ 0.87
First Hour Rating≥ Max GPM at 67°F ΔT


Modern gas water heaters— either traditional or tankless— are safe to use as long as all of the safety guidelines are followed.

Improperly installed or maintained gas lines can leak and become a hazard. Therefore, scheduled professional maintenance on piping and heater units is necessary. Make sure that at the very least, your heater is checked once a year.

Although extremely rare, it has been known for storage tanks on traditional gas heaters to explode from pressure build-up caused by a defective pressure relief valve. By checking the relief valve periodically, this shouldn’t happen throughout the lifespan of a gas heater.

Additionally, an Energy Star can also tell you whether the model has met safety regulations. Part of the criteria for an Energy Star is meeting ANSI Z21.10.3/CSA 4.3, a robust safety guideline of the American National Standards Institute (ANSI).


The length of the warranty is often determined by the product life cycle. Your service agent can use this information to deduce the frequency of maintenance your heater needs.

Once again, an Energy Star is also a valuable resource. Certified traditional heaters must have six years or more on the warranty for the whole unit, including parts. Tankless heaters must have over six years on the heat exchanger, and over five years for parts.

With all of the requirements for a good gas heater stated, it’s time we move to the reviews.

The Best Gas Water Heaters in 2021: Reviews

The following is a list and brief comparison table for all of the best gas water heaters that are going to be featured in our review:

  1. GASLAND BS318Best to Buy Gas Water Heater
  2. Rinnai RUC98iNBest Value Gas Water Heater
  3. Rinnai V65iNBest Tankless Gas Water Heater
  4. Rheem RTGH-95DVLNBest Natural Gas Water Heater
  5. A.O. Smith GPVL-50 ProMaxBest 50 Gallon Gas Water Heater
NameFlow RateFuel TypeWarranty
GASLAND BS3183.18 GPMPropane1-year warranty
Rinnai RUC98iN9.8 GPMNatural Gas12-year on heat exchanger, 5-year on parts, 1-year on labor upgradable to 5-year.
Rinnai V65iN6.5 GPMNatural Gas10-year on heat exchanger, 5-year on parts, 1-year on labor
Rheem RTGH-95DVLN9.5 GPMNatural Gas10-year on heat exchanger, 1-year on parts
A.O. Smith GPVL-50 ProMaxFirst Hour Rating: 90 Gallons
Recovery Rate: 44.7 GPH
Natural Gas or Propane6-year on tank and parts

1. GASLAND BS318 – Best to Buy in 2021

The GASLAND BS158 is a versatile and adaptable tankless gas heater that can be used both indoor and outdoor. It produces a good amount of hot water, making it a fitting choice for RV-ers or mariners needing hot water on the go. Small residences wanting a point-of-use heater or has low hot water demand can also benefit from the BS158.

Gasland BS318 Outdoors Propane Water Heater


  • Affordable
  • Modest performance
  • Durable for outdoor use
  • Compact and portable
  • Numerous safety features


  • Short warranty

High Portability

Since it’s an outdoor heater designed to work with temperamental water supply at campgrounds or RV parks, it can be connected to a portable water pump when the inflow pressure is too low or unstable. Under optimum inflow water conditions, the heater can produce a constant 3.18 GPM stream of hot water and is enough to supply two water-saving showerheads.

The unit itself is lightweight at around 25.9 pounds and can be quickly mounted on a wall bracket of an RV or a house. Dimension-wise, the BS318 is quite compact— about the size of a backpack— so you won’t have much trouble finding a storage space for it. The burner is ignited with two D-batteries with no need for any electrical connection.


Naturally, since there is some risk involved with a mobile gas unit, it has a number of safety mechanisms. One is a flame failure device to stop the flow of propane to the burner when the flame is extinguished. Another is an anti-freezing mechanism to protect the unit from cold temperatures, as well as an anti-overheating protection mechanism with automatic shutdown.

When used indoors, it is important to make sure that the heater is connected to a 4.33” diameter flue pipe or air duct, or is installed in a well-ventilated area. If you are a hiker or mountaineer, it is worth keeping in mind that the heater cannot perform at altitudes higher than 3,300 feet or in strong wind.


The warranty is only one-year on the whole unit which is understandable for an outdoor heater at greater risk of damage. However, according to customers, with proper usage and upkeep, the unit can last four to five years before needing a replacement.

2. Rinnai RUC98iN – Best Value Gas Water Heater

The Rinnai RUC98iN is a heavy duty gas water heater that can cater to the largest of residences. It’s also energy efficient with low emissions, so you get a lot more for the money you spend.

Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater


  • High performance
  • Energy efficient heat condenser
  • Recirculation system
  • Numerous safety features
  • Low emission
  • Comprehensive warranty


  • High unit cost

Water Condensing Tech

The key to this gas heater’s efficiency is the use of integrated condensing technology, which is also able to maintain an impressive hot water rate of 9.8 GPM. The problem with water heater design— both traditional and tankless— is the amount of heat energy wasted in venting hot gases. With a second heat exchanger, the RUC98iN recaptures heat and reroutes it back into the heater to preheat the cold inflow water.

Because the vented gas, with most of its energy now removed, is much cooler than a non-condensing heater, you can use a low cost PVC or a concentric vent instead of the standard stainless steel. This is how the RUC98iN attains a 0.96 EF or 0.92 UEF as well as an Energy Star rating.

Circ-Logic Recirculation System

Another notable feature of the RUC98iN is the Circ-Logic recirculation system. Heaters without recirculation tech need some time to heat the cold inflow water when switched on. Circ-Logic routes the left-over hot water back to the heater unit and reheats it at regular intervals. The result is instant hot water the moment you turn on your tap, showerhead, or sink.


The controls are completely digitized with a small LCD screen displaying the temperature. There are buttons to change the temperature, turn the heater on or off, and adjust basic settings. The heater is also shipped with a MC-91-2US remote control. You can place the control anywhere you want as long as it’s wired back to the heater using a basic thermostat wire. The remote for the Circ-Logic system, or a waterproof one for use inside the bathroom, are separate purchases.

Safety and Assurances

Rinnai has plenty of safety mechanisms including a flame failure device, overheating protection, a thermal fuse, an electrical overload fuse, and anti-frost.

There’s also a combustion fan RPM sensor which regulates the oxygen flow to the combustion chamber to streamline fuel burning. If the fan doesn’t spin due to a malfunction or low RPM, the burner will either not start, or produce an unstable burn. The sensor can be a handy troubleshooting tool when you notice a drop in the heater’s performance.

For residential use, Rinnai offers a twelve year warranty on the heat exchanger, and five years on parts. Labor has a one year warranty, with the option to increase it to five.

3. Rinnai V65iN – Best Tankless Gas Water Heater

There are several reasons that make this Rinnai one of the highest rated heaters and an ideal choice for most households. It’s reliable yet moderate performance keeps up with demand, and the smart control system is desirable for a lot of people.

Rinnai V65iN High Efficiency Tankless Hot Water Heater


  • Affordable
  • Moderate performance
  • Smart control option 
  • Multiple safety mechanisms
  • Comprehensive warranty


  • Not so efficient


The V65iN is a natural gas heater with a maximum flow rate of 6.5 GPM with optimal groundwater temperature. That’s enough to supply a standard showerhead, a washing machine, a dishwasher, and an energy-saving sink at the same time. The burner may consume up to 150,000 BTUs/hour at its peak, equivalent to 147 cubic feet of gas/hour or roughly $1.36/hour at current gas rates.

The V65iN requires a 120 volt – 60 Hz AC power source. The heater’s normal operation consumes 76 watts and 2 watts on standby, and the maximum amperage draw is 4A. Since the UEF of the heater is only about 0.72 to 0.82, it’s not qualified for an Energy Star rating.


The control interface is basic, but has an optional WiFi module (Control-R). This allows you to control the temperature and other settings via Rinnai’s app. A small LCD screen shows the temperature, with buttons for changing settings, and the power switch. It’s shipped with an MC-91-2US remote controller.

Safety and Assurances 

All standard safety mechanisms are included, such as overheating and circuit overload fuses, a combustion fan RPM sensor, a flame failure device, anti-frost and more. The warranty package includes ten years on the heat exchanger, 1 year on labor, and five years on parts.

4. Rheem RTGH-95DVLN – Best Natural Gas Water Heater

The Rheem RTGH-95DVLN is a heavy duty, whole house, tankless system with a proven track record. Its performance can satisfy the most demanding households, and its efficiency also translates into lower running costs. 



  • Affordable
  • Moderate performance
  • Smart control option 
  • Multiple safety mechanisms
  • Comprehensive warranty


  • Not so efficient


The natural gas burner has a maximum gas input of 199,000 BTUs/hour or 196 cu.ft /hour). Based on the current national average of $9.26 per 1.000 cu.ft, running costs at full capacity would be just less than $2 per hour ($1.81). Its maximum flow rate of 9.5 GPM is also top rated and can supply two bathrooms with a standard showerhead and a sink, with enough capacity to spare for a washing machine.

The RTGH-95DVLN is also a condensing heater, so it recycles vented heat and  doesn’t require an expensive vent other than a PVC pipeline. However, although it has  an EF of 0.94, it doesn’t have an Energy Star rating. 

A 120 volt – 60 Hz AC power supply is required and it has a max amperage draw of two amps. The heater may consume 100 watts during normal operations, and three to five watts on standby. 

Controls and Safety

There are no controls directly on the unit like in other tankless heaters, but it does ship with a remote control and 10 feet of thermostat wire. The remote can also display maintenance codes for self-diagnosis.

Safety mechanisms include a flame failure device, overheating and overloading fuses. The warranty is ten years on the heat exchanger and one year on parts, which is about as generous as it comes.

5. A.O. Smith GPVL-50 ProMax – Best 50 Gallon Gas Water Heater

If you prefer the simplicity of a traditional heater, the A.O. Smith GPVL-50 ProMax is a nice whole house solution with a 50 gallon storage tank.

A.O. Smith GPVL-50 ProMax Power Vent Gas Water Heater


  • Household capacity 
  • Energy efficient
  • Low maintenance
  • Low cost venting
  • Multiple safety mechanisms


  • High unit cost


The 50 gallon tank has a high-grade 40,000 BTU burner which secures 90 gallons for the first hour rating, with a recovery rate of 44.7 GPH (at 90°F rise.) This can easily provide enough hot water for a household of three to four people. The heater’s EF rating is 0.7, which qualifies for an Energy Star rating. 

Efficiency is boosted in a number of ways. The unit traps heat at the inlet and outlet to minimize energy loss, and the storage tank is insulated with foam. Additionally, instead of an energy wasting pilot light, the GPVL-50 ProMax uses a hot surface ignitor. Like a hot plate, the ignitor exploits electrical resistance to light up the gas, which is far more efficient and reliable.

The heater uses a power vent design with a 3-position rotatable, motorized blower to force the vented gas out. As for the vent material, the heater is compatible with plastic vents (ABS, PVC, CPVC, and PP) which are cheaper than stainless steel ones.


The digital LED control panel at the bottom of the heater displays several parameters which can also be used for diagnosing problems.


Unique to A.O. Smith’s ProMax series, the GPVL-50 features the DynaClean II diffuser dip tube. The tube is made from cross-linked polymer, which is more durable and requires less maintenance. It also reduces lime and sediment in the tank. Additionally, the storage tank is coated with Blue Diamond glass to harden the tank against corrosion.

Safety and Assurances

Safety is handled by the computer system and other automated mechanisms including a gas shut-off device, and a fuel vapor sensor that shuts the burner down in case of a fuel leak. Additionally, there’s an air intake snorkel to prevent flammable fuel vapor from entering the combustion chamber.

It comes with a six year period of limited warranty for the tank and parts.

Safety Tips For Using Gas Water Heaters

The numerous safety mechanisms on modern heaters mean the possibility of a dangerous mishap is highly unlikely as long as you properly maintain your heater. However, there are still a couple of things that you can do to further ensure the safety of yourself and your family.

Invest in a Carbon Monoxide Detector and a Fuel Leak Detector

Modern heaters burn cleanly and release very little Carbon Monoxide (CO). However, in the rare case of the vent being blocked, causing gas seepage into the house, or the heater leaking, it’s best to have a carbon monoxide detector— as one would with any gas appliance. 

We also recommend installing a gas leak detector. Although propane and natural gas are both odorless, manufacturers usually add scented chemicals, which is why gas has that tell-tale rotten egg smell. Still, it’s a good idea to have detectors around the house just in case.

Clear the Surrounding Space

The air in the installation room should be clean and free of chemicals and smells that could mask a gas leak. There shouldn’t be any combustible materials like papers, aerosol cans, fuel canisters, or chemical cleaners in the room.

A wall-mounted heater (mostly tankless), should be mounted as high as possible. Most gas fumes are heavier than air, so elevating the heater will allow for faster and easier detection of gas leaks lower down.

Periodic Professional Maintenance

Contact your local plumber or heating technician to periodically check the heater, the piping, and the detectors to make sure everything is in working order. Even small jobs such as replacing the batteries in the detectors can go a long way in safeguarding your home.


We hope this buying guide has helped your understanding and that you have found the best gas water heater for your needs. There are dozens to choose from, but our selection is the most promising yet!

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