Definition and Brief Overview

Tankless water heaters, both gas and electric models, provide hot water on demand without the need for a storage tank. By heating water directly as it flows through the unit, they offer a continuous supply of hot water and improved energy efficiency compared to conventional water heaters. This guide will help you make an informed decision between gas vs electric tankless water heater. You will understand the main differences ad pros and cons of each

Importance of Choosing the Right Water Heater

Selecting the right water heater is crucial for meeting your household's hot water needs efficiently and cost-effectively. Whether you opt for an electric or gas tankless water heater depends on your existing natural gas availability, electrical supply, and hot water demand.

Advantages of Tankless Over Traditional

Tankless water heaters, devoid of standby energy losses associated with storage tanks, are more energy-efficient. They occupy less space and can significantly reduce energy costs, making them a favorable choice over conventional tank water heaters.

Brief Explanation of Gas and Electric Types

Gas tankless water heaters utilize natural gas or propane to heat water on demand, requiring adequate ventilation for safe fuel combustion. Electric tankless models, on the other hand, use electrical power to heat water and are known for their simpler installation and the absence of combustion air supply requirements.

Gas Tankless Water Heaters

A. How They Work

Heating Mechanism

Gas tankless water heaters utilize a high-efficiency heat exchanger activated by natural gas or propane service, instantly heating water on demand. This system eliminates the need for a traditional storage tank, ensuring that hot water is readily available without the standby energy losses associated with conventional tank water heaters.

Advantages and Drawbacks

The key advantage of gas tankless heaters lies in their ability to deliver a continuous supply of hot water, catering to high hot water demands efficiently. Despite their energy efficiency and reduced greenhouse gas emissions, the complexity of venting requirements and the initial installation cost pose significant drawbacks.

B. Key Factors to Consider

Flow Rate and Capacity

Choosing a gas tankless water heater involves careful consideration of its flow rate and capacity to meet your household's peak hot water demand. Adequate sizing is crucial to avoid running out of hot water during high demand periods.

Energy Efficiency Ratings

The Energy Factor (EF) rating of gas tankless water heaters indicates their energy efficiency. Higher EF values denote more efficient units, leading to lower energy costs and fewer greenhouse gas emissions, making them a more environmentally friendly option compared to electric tankless models or conventional gas water heaters.

Venting and Installation

Gas tankless water heaters require proper venting to ensure safe fuel combustion and to prevent the accumulation of hazardous gases. Installation costs can be influenced by the complexity of venting and the need to comply with local building codes, which may dictate specific requirements for side wall venting or roof venting.


Regular maintenance, including servicing the heat exchanger, checking the inlet screen filter, and ensuring the venting system is unobstructed, is essential for maintaining the efficiency and safety of gas tankless water heaters. Neglecting these maintenance requirements can lead to higher gas consumption and increased operating costs.

C. Pros and Cons

  • Energy Efficiency and Cost Savings: Gas tankless water heaters offer significant energy savings by heating water only when needed, reducing energy costs and minimizing greenhouse gas emissions compared to their electric counterparts or conventional storage tank heaters.
  • Unlimited Hot Water: These units provide an endless supply of hot water, ideal for large households or those with high hot water usage habits, without the worry of depleting a storage tank.
  • Initial and Installation Costs: The upfront purchase and installation costs of gas tankless water heaters, including the need for adequate gas lines and complex venting systems, can be substantially higher than those for electric tankless water heaters or traditional gas models.
  • Maintenance and Venting Requirements: Regular maintenance to ensure safe fuel combustion and adherence to venting requirements can add to the long-term costs and complexity of owning a gas tankless water heater, making electric models a potentially more straightforward and cheaper installation option for some households.

 Electric Tankless Water Heaters

A. How They Work

Heating Mechanism

Electric tankless water heaters harness high-powered electrical heating elements to instantly warm incoming water, eliminating the need for a conventional storage tank. This direct heating approach ensures efficient water heating without the standby energy losses associated with traditional water heaters, offering a cost-effective solution, particularly in homes with adequate electrical supply.

Advantages and Drawbacks

A key advantage of electric tankless models is their streamlined installation and minimal maintenance, attributed to the absence of a combustion process, thus reducing greenhouse gas emissions. However, the reliance on electricity means their operational efficiency can be heavily influenced by local electricity prices and the demand for very high power appliances within the household.

B. Key Factors to Consider

Flow Rate and Capacity

Evaluating the flow rate and capacity is essential when selecting an electric tankless water heater, as it must meet the peak hot water demand efficiently. Units that fall short in capacity can lead to a disappointing performance, especially during simultaneous hot water usage.

Energy Efficiency Ratings

The energy efficiency of electric tankless heaters is often measured by the Uniform Energy Factor (UEF), where higher ratings indicate greater efficiency. Given the fluctuating electricity prices, opting for a unit with a high UEF can lead to more energy savings and a reduction in operating costs, despite the generally higher energy consumption associated with electric units.

Electrical and Installation Considerations

Electric tankless water heaters require a robust electrical service capable of handling the high power demand. Installation may involve upgrading the home's existing electrical system to accommodate the heater, which can affect the installation cost. Additionally, the simplicity of electric models often allows for cheaper installation compared to gas tankless heaters, which require complex venting and an adequate gas supply.

Maintenance Requirements

Maintenance for electric tankless heaters typically involves periodic checks of the heating elements and cleaning the inlet screen filter. This straightforward maintenance schedule contrasts with the more involved requirements of gas tankless models, which need regular checks for safe fuel combustion and venting efficacy.

C. Pros and Cons

  • Simplified Installation and Maintenance: Electric tankless water heaters often boast a more straightforward and significantly cheaper installation process than gas models, thanks to the lack of gas lines and complex venting systems. Their maintenance is typically less demanding, focusing on electrical components and water inlet filters.
  • Eco-Friendly Operation: By eliminating the combustion process, electric tankless heaters contribute to lower greenhouse gas emissions, aligning with energy-efficient and environmentally conscious water heating solutions.
  • Dependency on Electricity Rates: The operational efficiency and cost-effectiveness of electric tankless water heaters are directly affected by local electricity prices. In areas with high electricity rates, these units can incur higher running costs compared to natural gas or propane-powered models.
  • Performance in Cold Climates: The efficiency of electric tankless heaters can be compromised in colder climates, where the lower incoming water temperatures demand more electrical power to heat the water to desired temperatures, potentially leading to insufficient hot water supply for the household's needs, especially during peak usage times.

Comparison between Gas and Electric Tankless Water Heaters

A. Energy Efficiency Comparison

Efficiency Ratings Explanation

The energy efficiency of tankless water heaters is quantified through the Energy Factor (EF) for gas models and the Uniform Energy Factor (UEF) for electric tankless water heaters. Higher EF or UEF values signify a unit's superior ability to convert its energy source, whether natural gas or electricity, into hot water efficiently.


While gas tankless heaters are valued for their ability to heat water rapidly, their EF ratings can be lower due to energy losses during venting. Electric tankless water heaters, conversely, typically showcase higher UEF ratings, reflecting their more efficient use of electrical power to heat water, making them particularly energy-efficient in warmer climates where less heating is required.

B. Cost Considerations

Initial Cost

Electric tankless water heaters often present a lower initial cost compared to gas tankless water heaters, primarily due to the simpler installation process that doesn't require complex gas lines or venting systems, making them a cost-effective choice for many.

Operating Costs

The operating costs of gas tankless water heaters can be advantageous in areas with low natural gas rates, but volatile gas prices can impact long-term affordability. Electric tankless models may have higher operating costs, particularly in regions where electricity prices are steep, affecting the overall energy costs of water heating.

Maintenance Costs

Maintenance costs for gas tankless heaters tend to be higher due to the necessity for regular checks of the venting system and combustion air supply to ensure safe fuel combustion. Electric tankless models, on the other hand, usually demand less maintenance, contributing to lower long-term costs.

C. Performance and Output Comparison

Hot Water Rate and Capacity

Gas tankless water heaters excel in providing high flow rates, making them ideal for larger households with substantial hot water needs. Electric tankless heaters, while efficient, may not match the high gas consumption capacity of gas models, especially in settings with simultaneous hot water demands.

Temperature Control

Both gas and electric tankless heaters offer precise temperature control. However, gas models are often preferred for their consistent performance under varying demands, leveraging the readily available natural gas or propane service.

Longevity and Reliability

Generally, gas tankless water heaters boast a longer service life, attributed to their robust design capable of enduring high hot water demand scenarios. Electric tankless heaters, though reliable, might exhibit a shorter lifespan in heavy use environments due to the stress on electrical components.

D. Specific Scenarios Considerations

Large Households

For households with significant hot water usage, gas tankless water heaters are typically better suited due to their superior capacity and quick response to high demand, ensuring a steady supply of hot water.

Climate and Temperature

In colder climates, gas tankless heaters are often more effective, less impacted by the cold incoming water temperature, and capable of maintaining efficiency despite high gas consumption. Electric models may require additional capacity to offset the efficiency loss due to colder incoming water temperatures.

Availability and Cost of Gas

The decision between gas and electric tankless water heaters can also be influenced by the local availability and cost of natural gas. In areas lacking existing natural gas infrastructure or where gas rates are high, electric tankless water heaters emerge as a more accessible and potentially more cost-effective solution, sidestepping the complexities of gas model installation and the fluctuating gas prices. Conclusion

Recap of Advantages and Disadvantages

Electric tankless water heaters offer ease of installation and lower upfront costs, making them an attractive option for many homeowners, especially those concerned about reducing greenhouse gases. Gas tankless models, however, are often favored for their higher flow rates, capable of supplying enough hot water simultaneously to various fixtures like showers and dishwashers, albeit with potentially higher overall costs due to gas prices and the need for ventilation.

Factors for Individual Consideration

Key factors for homeowners to consider include the existing infrastructure (e.g., availability of an incoming gas line or adequate electricity), the home's hot water demand, and energy sources' cost-effectiveness in their region. The choice may also depend on the location's specific requirements, such as rural areas where natural gas might not be readily available, influencing the decision towards electric tankless units.

Final Recommendation

For those in many locations looking to install a tankless water heater, the decision between gas and electric models should account for the household's size, hot water usage habits, and the long-term impact on energy costs. Electric tankless heaters could be more suitable for smaller homes or those with limited hot water needs, offering a less expensive and easier-to-install solution. In contrast, gas tankless heaters might be the better choice for larger families or homes in areas with lower gas rates, where their efficiency and ability to produce a higher flow rate of hot water can more effectively meet the demands, despite the initial higher investment and the need for professional installation to ensure proper ventilation.

FAQs on Tankless Water Heaters

Is it better to have a gas or electric tankless water heater? The choice between gas and electric tankless water heaters depends on several factors, including your home's existing infrastructure, hot water needs, and energy costs in your region. Gas tankless heaters typically offer a higher flow rate, making them suitable for homes with significant hot water demand. Electric models, while generally cheaper to install and requiring less space, might be more suitable for smaller households or areas without easy access to natural gas.What is the downside of a gas tankless water heater? Gas tankless water heaters require proper ventilation to expel combustion gases, which can complicate installation and increase costs. They may also have higher initial costs compared to electric models. Additionally, fluctuating gas prices can affect the overall cost of operating a gas tankless water heater.Why not to buy an electric tankless water heater? One potential downside of electric tankless water heaters is their dependency on your home's electrical service's capacity. Homes without sufficient electrical power may require expensive upgrades. Electric models may also struggle to provide a high flow rate of hot water simultaneously to multiple fixtures, especially in colder climates where the incoming water temperature is much lower.Is it cheaper to heat water by gas or electric? The cost-effectiveness of heating water by gas or electric depends on local utility prices and the efficiency of the unit. Generally, natural gas is less expensive than electricity in many regions, making gas water heaters cheaper to operate. However, electric tankless water heaters tend to have higher efficiency ratings, which can offset the higher cost of electricity in some cases.Should I convert my gas water heater to electric? Converting from gas to electric might be worth considering if you have limited access to natural gas, prefer a lower maintenance solution, or wish to reduce greenhouse gas emissions. However, consider the cost of such a conversion, including any necessary upgrades to your home's electrical system, and compare it to the potential benefits and savings.What is the cheapest way to heat water? The cheapest way to heat water often involves using the most efficient water heater that aligns with the lowest-cost energy source available in your area. For some, solar water heaters might offer the lowest operational cost, albeit with higher initial investment. In areas with low natural gas prices, a high-efficiency gas water heater could be most cost-effective. Electric tankless water heaters can also be economical, especially in homes with lower hot water demands or where electricity rates are favorable.Can tankless water heaters handle hard water? Tankless water heaters can be affected by hard water, which can lead to mineral buildup inside the unit, reducing efficiency and lifespan. Regular maintenance, including descaling, is recommended for areas with hard water. Installing a water softener can also help prolong the life of a tankless water heater.How long do tankless water heaters last? Tankless water heaters typically have a longer lifespan compared to traditional tank heaters. On average, a tankless water heater can last up to 20 years or more with proper maintenance, compared to 10-15 years for conventional tank models.