Gas Vs Electric Tankless Water Heater: Which Is Best

Gas Vs Electric Tankless Water Heater: Which Is Best

Anthony Barnes

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For years, there has been a huge debate between gas and electricity. Especially when it comes to choosing a new tankless water heater.

In some areas, there isn’t a choice, and you can only have one. However, if you happen to have a choice, then it can be quite overwhelming knowing which one you should select that will suit your needs.

In this article, we will be discussing the difference between a gas and electric tankless water heater (see also ‘Why Using A Tankless Water Heater For Radiant Floor Heating Is A Good Idea‘). Ultimately coming to a conclusion on which one is best.

Gas Vs Electric Tankless Water Heater


When it comes to installing your water heater, you should hire a professional to do the job. They will have experience and know what they are doing.

A tankless water heater is also a huge money investment, so you want to make sure that it is properly and safely installed as well. 


A gas tankless water heater (see also ‘Tankless Water Heater Vs. Tank‘) is much more expensive and complicated to install when compared to an electric one. 

A reason why it is much more complicated to install is because the gas lines and venting ducts are rarely compatible with the chosen tankless gas water heater.

This modification to the home has to be made to accommodate the needs of the gas water heater. 


An electric tankless heater is much cheaper and easier to install. Alongside that, you will notice that an electric tankless water heater is around 1/3 smaller than a gas water heater.

This is because no form of combustion needs to take place, and an electric water heater doesn’t need ventilation like a gas system does. 

As a result, you have much more options of where you can install an electric tankless water heater due to their small size.

However, for older homes, the electrical system in place may not be able to meet the demands of the electric water heater.

Therefore, you would have to upgrade the electric in your old home if you really wanted an electric system, which is expensive. 

Operating Costs

There are two elements that make up the operating costs for any tankless water heater. These include the cost of the fuel and the efficiency of the system.

The cost of gas and electricity are constantly going up and down. Also, fuel costs differ in every region and state.

Therefore, in some area’s electricity is cheaper than gas and vice versa.

Although, it has been predicted that gas prices will constantly go up over the years, while electricity will stay at a steady price. 

Also, the efficiency of a system is based on the amount of water that is created by 1 unit of fuel.

The more efficient a heater is, the less fuel it needs to use or easy to get the water hot. It is known that electric systems are often much more efficient than gas systems.  


When it comes to a tankless gas water heater (see also ‘ Operating A Tankless Gas Water Heater Without Electricity ‘), it is known to have an efficiency rating of around 80 to 85%.

However, the price of gas is always fluctuating, so the price of gas to run your tankless heat can go up or down all the time. Thus, it’s difficult to say if it is more reasonable to run than an electric system. 


On average, an electric tankless heater will reach an efficiency of around 98 to 99&. Making it far more efficient than a gas tankless water heater.

Sometimes the price of electricity is far higher than gas, yet as this system is much more efficient it helps to balance out the cost. 


Every tankless water heater reaches some form of maintenance on it from time to time. This is to help it to keep working as efficiently as possible and also prolong their service life. 


With a gas water heater, it is known to come with a lot more maintenance needs.

You need to have this system inspected at least once a year by a technician. They will make sure the combustion process is working properly and safely.

Alongside this, a gas water heater (see also ‘Should You Invest In Water Heater Booster‘) is much more prone for sediment to build up from minerals that haven’t been caught in the filtration system. This build up can cause performance issues if not flushed away regularly. 

If small issues occur on a gas water heater, then you can complete them yourself. However, you can also hire a professional to do the job as well.  


An electric water heater doesn’t have as much maintenance needs when compared to a gas water heater. However, the inlet water screen filter should be cleaned once it starts to look dirty.

Also, the electric system should be flushed annually. This will remove any limescale that has built up from the water. 

Although, if you do have any issues with your electric system, then it is best to hire a professional to fix the problems than trying to do it yourself. 

Service Life And Warranty

A tankless system has been created and built to last. Compared to a water heater with a tank that will after around 10 years begin to form leaks and need to be replaced.

While a tankless system has been created to be constantly repaired instead of replaced. 

On average, a tankless heater, whether that be a gas or electric system, has a service life of around 20 years. Which is double of a tank-style water heater.

There are many things that can affect the life of a water heater, this can be sediment buildup, not installed properly or not maintained frequently enough. 


A gas system is said to have a lifespan of around 20 years. The warranty of a gas unit can vary, you  may see a 10-year warranty on the heat exchanger or 5-year warranty on parts. There is also a 1-year warranty for labor. 

The service life of a gas unit can be hugely impacted if the water heater (see also ‘Wood Burning Water Heaters | How It Works, Types, Buying Tips‘) isn’t maintained or served frequently. 


Often an electric water heater will exceed its 20-year lifespan as it has such a simple design. Again, the warranty can vary depending on the make and model of the system.

However, parts normally have a 5-year warranty and there is a 1-year Hannity on labor.

If there is an issue with your electric tankless water heater (see also ‘ 4500 Vs 5500 Watt Water Heater ‘), it is much easier to find the issue and repair it. 

Hot Water Production

This is all about how many gallons per minute (GPM) can a system deliver. The general idea is that 8 GPM is the right amount of water for an average family.

However, you also need to think about your household needs and how much water you need. No one wants to run out of hot water during their shower. 

It is known that colder areas have a lower GPM rate than warmer areas. As the water is much cooler already, the system needs to work a bit harder to heat the water to the right temperature.

It is believed that gas slightly has the edge in this area, when it comes to larger volumes of water. 


It is known that a tankless gas water heater can easily produce more than 8 GPM when needed.

Thus, for a larger family a gas water heater (see also ‘Gas Hot Water Heater Installation‘) may be a better choice as you will have a higher demand for hot water and gas can keep up with the need. 


Whilst an electric system can produce up to 8 GPM of hot water, however, it may struggle if there is a super high demand. 

Although, the output of both systems are affected by the temperature of the water that is coming in.

Therefore, if colder water is entering, then the GPM is going to be much lower than the average. 

Final Thoughts

As you can see, there is a lot to think about when it comes to the great gas or electric tankless water heater debate.

It is difficult to say which one is better because everyone’s needs are different, thus the best tankless water heater for you depends on what you need. 

A lot of professionals will say that an electric system is the better choice, as they are easier to install and much less expensive to buy and maintain. 

However, a gas system is the ideal choice, if you have higher than average water needs. Although, a gas tankless water heater does require a lot more maintenance and can be difficult to know what is causing issues with it. 

Which type of system is up to you and your needs. We hope this article has helped you to come to a decision on which type of tankless water heater will be much more beneficial for you and your household. 

Thank you for reading!

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By Anthony Barnes

Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age