When it comes to providing hot water in your home, homeowners today have two primary options: tankless water heaters and traditional storage tank water heaters. While both serve the same essential function, there are significant differences in how they operate, their initial and ongoing costs, installation requirements, energy efficiency, and overall performance.
As an experienced water heater specialist writing for WaterHeaterPick.com, I’ll provide a detailed comparison of these two water heating methods to help you determine which is the best fit for your home.
Water Heater Types
Tankless Water Heaters
Tankless, or on-demand, water heaters heat water instantly as it flows through the unit, rather than storing pre-heated water in a tank. These compact wall-mounted appliances use either electricity, natural gas, or propane to rapidly heat water only when there is a demand for hot water.
The lack of a storage tank is a key advantage of tankless water heaters, as it eliminates the “standby” energy losses associated with continuously reheating water in a tank. Instead, tankless models heat water on an as-needed basis, providing an endless supply of hot water as long as the unit can keep up with demand.
Tankless water heaters come in both electric and gas-fired models. Electric tankless heaters are generally less expensive upfront but may require upgrading your home’s electrical service to accommodate their higher power draw. Gas tankless models tend to have higher initial costs but can be more cost-effective to operate, especially in areas with lower natural gas rates.
Storage Tank Water Heaters
The traditional storage tank water heater is the more common type found in most homes. These units store a reserve of pre-heated water, typically ranging from 30 to 80 gallons, and use either electricity, natural gas, oil, or propane to maintain the water temperature.
When hot water is needed, it is drawn from the top of the tank, and cold water refills the tank from the bottom. This continuous heating cycle to keep the water at the set temperature results in some “standby” energy losses, which can impact operating costs.
Storage tank water heaters come in a variety of sizes to meet the hot water demands of different household sizes. Larger capacity tanks generally cost more upfront but may be necessary for homes with higher hot water usage. Homeowners might want to also consider the physical space required to accommodate the size of the tank in their home.
Water Heater Maintenance
Proper maintenance is essential for ensuring the long-term reliability and efficiency of both tankless and storage tank water heaters. Regular servicing can also help extend the lifespan of these appliances.
Tankless Water Heater Maintenance
Tankless water heaters require periodic maintenance to keep the heat exchanger and internal components clean and functioning optimally. This typically involves flushing the unit with a descaling solution to remove any mineral buildup, as well as inspecting and cleaning the water inlet filter.
Manufacturers often recommend flushing a tankless water heater annually, especially in areas with hard water. Some models may also need the anode rod replaced periodically to prevent corrosion. Keeping up with this maintenance can help double-check that your tankless water heater operates at peak efficiency and avoids potential breakdowns.
Storage Tank Maintenance
Traditional storage tank water heaters also benefit from regular maintenance, such as draining the tank to remove sediment buildup. This process helps prevent the formation of scale and corrosion, which can reduce the tank’s heating efficiency and lifespan.
Most experts recommend draining and flushing a storage tank water heater at least once per year. Homeowners should also inspect the anode rod and replace it if it shows significant deterioration. Keeping an eye on any signs of leaks or other issues can help identify potential problems before they become more serious.
Troubleshooting and Repair
When issues arise with a water heater, it’s important to address them promptly to avoid more significant damage or a complete breakdown. Both tankless and storage tank models may require professional diagnosis and repair from a licensed plumber, depending on the nature of the problem.
Common tankless water heater issues can include error codes, insufficient hot water production, or problems with the heat exchanger or electronic controls. With storage tanks, common trouble spots include leaks, sediment buildup, faulty thermostats, and failed heating elements or burners.
Homeowners should familiarize themselves with the basic troubleshooting steps for their specific water heater model, as well as have a trusted plumber’s contact information on hand in case more advanced repairs are needed.
Plumbing Techniques
The plumbing requirements for installing and connecting a water heater, whether tankless or storage tank, can vary depending on the fuel source, location, and local building codes.
Pipe Materials and Selection
The type of piping material used to connect the water heater to the home’s plumbing system can impact the overall performance and longevity of the installation. Copper, PEX, and CPVC are common choices, each with their own advantages and considerations.
Copper piping is highly durable and corrosion-resistant, making it a reliable option, but it can be more expensive and labor-intensive to install. PEX tubing is flexible, easy to work with, and cost-effective, while CPVC offers a good balance of price, ease of installation, and resistance to scaling and corrosion.
Plumbing Connections and Fittings
Proper connections and fittings are crucial for ensuring a secure, leak-free installation. Threaded, compression, and push-fit fittings are all common options, each with their own strengths and appropriate applications.
Tankless water heaters, in particular, may require specialized hardware like flex connectors or unions to facilitate installation and future servicing. Attention to detail in the plumbing connections is essential for the safe and efficient operation of any water heater.
Plumbing Code Requirements
Local and national plumbing codes dictate the specific requirements for water heater installations, including venting, clearances, and safety features. Homeowners and plumbers might want to be familiar with the applicable codes in their area to double-check that the water heater installation meets all necessary regulations.
These code requirements can vary significantly based on factors like the water heater’s fuel source, location within the home, and proximity to other appliances or hazards. Working with a licensed, experienced plumber is highly recommended to navigate the complex code requirements for water heater installations.
Installation Methods
The actual process of installing a new water heater, whether tankless or storage tank, involves several key considerations to double-check that a safe, functional, and up-to-code setup.
Tankless Water Heater Installation
Tankless water heaters are generally more compact and easier to install than traditional storage tank models. However, the installation process can still be quite involved, especially if transitioning from a tank water heater to a tankless system.
Factors to consider include the unit’s power requirements (electric or gas), venting needs, water and gas line connections, and appropriate placement within the home. Many manufacturers recommend – or even require – that their tankless water heaters be installed by a licensed, factory-trained professional to maintain the warranty.
Storage Tank Installation
Installing a traditional storage tank water heater is typically a more straightforward process, as the appliance is often replacing an existing tank in the same location. However, homeowners should still carefully evaluate factors like the tank’s capacity, fuel source, and spatial requirements to double-check that a proper fit.
Proper venting, water and gas/electrical connections, and seismic strapping (in earthquake-prone areas) are all important considerations. As with tankless models, working with an experienced plumber is highly recommended to double-check that the storage tank water heater is installed safely and to code.
Safety Considerations
Regardless of the water heater type, safety should be a top priority during the installation process. This includes ensuring proper ventilation, secure connections, and the incorporation of essential safety features like temperature and pressure relief valves.
Tankless water heaters, in particular, may require additional safety precautions due to their higher-powered gas or electrical components. Proper venting, clearances, and shut-off mechanisms are crucial to mitigate risks.
Energy Efficiency
Both tankless and storage tank water heaters have their own advantages and disadvantages when it comes to energy efficiency and operating costs.
Energy Efficiency Standards
Water heaters sold in the United States might want to meet certain energy efficiency standards set by the U.S. Department of Energy. These standards, known as the Uniform Energy Factor (UEF), rate the overall efficiency of the water heater based on factors like insulation, heat loss, and energy consumption.
Tankless water heaters generally have higher UEF ratings than traditional storage tank models, indicating their superior energy efficiency. However, the specific UEF rating can vary depending on the fuel source, features, and overall design of the water heater.
Cost Savings and Utility Rebates
The increased energy efficiency of tankless water heaters can translate to significant cost savings on utility bills over time, especially for households with high hot water usage. Some studies have shown that tankless models can save homeowners up to 30% on their water heating costs compared to storage tank heaters.
To further incentivize the adoption of energy-efficient water heaters, many local utilities and government agencies offer rebates or tax credits for the installation of qualifying tankless or high-efficiency storage tank models. Homeowners should research available incentives in their area when selecting a new water heater.
Environmental Impact
The improved energy efficiency of tankless water heaters not only saves homeowners money but also has a positive impact on the environment. By consuming less energy to heat water, these systems reduce greenhouse gas emissions and the overall carbon footprint associated with home water heating.
For environmentally conscious homeowners, the environmental benefits of tankless water heaters can be an important factor in the decision-making process, alongside the potential cost savings.
Water Heating Capacity
Both tankless and storage tank water heaters are designed to provide hot water for a home’s various needs, but the way they meet that demand can differ significantly.
Household Water Demand
Determining the appropriate water heater size for a home requires an understanding of the household’s typical hot water usage. Factors like the number of occupants, the number and type of plumbing fixtures, and the frequency of use all contribute to the overall hot water demand.
Households with higher hot water needs, such as those with large families, multiple bathrooms, or frequent use of appliances like dishwashers and washing machines, may be better suited for a higher-capacity storage tank water heater or multiple tankless units.
Sizing Considerations
Choosing the right size water heater, whether tankless or storage tank, is crucial for ensuring adequate hot water supply without wasting energy or incurring unnecessary costs.
For storage tank models, the tank’s capacity, measured in gallons, is the primary sizing factor. Tankless water heaters, on the other hand, are typically sized by their maximum flow rate, measured in gallons per minute (GPM).
Consulting with a qualified plumber or using online sizing calculators can help homeowners determine the appropriate water heater capacity for their specific needs and home layout.
Performance Metrics
In addition to size, other performance metrics can help evaluate the capabilities of different water heater models. For storage tanks, the recovery rate (how quickly the tank can reheat after hot water is used) is an important consideration.
For tankless water heaters, the minimum flow rate (the amount of water flow needed to activate the unit) and the maximum temperature rise (the difference between the incoming and outgoing water temperatures) are key specifications to review.
Understanding these performance metrics can help homeowners select the water heater that best meets their household’s hot water demands.
Lifespan and Durability
The overall lifespan and durability of a water heater can have a significant impact on the long-term cost of ownership, making it an essential factor to consider.
Tankless Water Heater Lifespan
Tankless water heaters are generally known for their extended lifespan, with many models rated for up to 20 years of reliable operation. This is due in part to the lack of a storage tank, which can be prone to corrosion and sediment buildup over time.
However, the lifespan of a tankless water heater can be influenced by factors such as water quality, maintenance practices, and the frequency of use. Homeowners in areas with hard water may need to perform more frequent descaling and cleaning to prevent premature wear on the heat exchanger and other components.
Storage Tank Lifespan
Traditional storage tank water heaters typically have a shorter expected lifespan, with most models lasting around 10 to 15 years. The storage tank itself is susceptible to corrosion and mineral buildup, which can eventually lead to leaks and complete system failure.
Proper maintenance, such as regular flushing and anode rod replacement, can help extend the lifespan of a storage tank water heater. But even with diligent care, these units will eventually need to be replaced as they approach the end of their useful life.
Maintenance Impact on Lifespan
The level of maintenance required for both tankless and storage tank water heaters can have a significant impact on their overall lifespan and performance. As mentioned earlier, regular servicing and cleaning are essential for ensuring the longevity and efficiency of these appliances.
Homeowners who are proactive about maintaining their water heaters, whether through DIY tasks or professional service, can often extend the usable life of the unit and avoid costly, unexpected breakdowns.
Aesthetic and Space Considerations
Beyond the technical aspects of water heater performance and efficiency, the physical size and appearance of the appliance can also be an important factor for some homeowners.
Tankless Water Heater Design
Tankless water heaters are known for their compact, wall-mounted design, which can be a significant advantage in homes with limited space or where traditional storage tank models would be difficult to accommodate. This streamlined profile can also be more visually appealing, allowing the water heater to be installed in relatively discreet locations.
The smaller footprint of tankless units also provides greater flexibility in terms of placement, as they can often be installed in closets, utility rooms, or even outdoors, depending on the model and local code requirements.
Storage Tank Placement Options
In contrast, traditional storage tank water heaters require a dedicated space to house the larger, freestanding appliance. This can be a consideration for homeowners with finished basements, tightly-packed utility rooms, or homes without a basement or ground-floor utility space.
While storage tank water heaters can be placed in attics or crawl spaces in some cases, the physical size and weight of the unit may limit the viable placement options, especially in older homes with more compact floor plans.
Architectural Integration
For homeowners concerned with the aesthetic integration of their water heater, tankless models often have a more streamlined, modern appearance that can blend seamlessly into the home’s architecture. Storage tank water heaters, with their larger size and traditional cylindrical shape, may require more consideration to double-check that they don’t clash with the surrounding decor or design.
In some cases, storage tank water heaters can be concealed within dedicated enclosures or cabinetry to improve their visual appeal, but this added step can increase the overall installation cost and complexity.
Ultimately, the choice between a tankless or storage tank water heater should consider not just the technical specifications and cost, but also the physical constraints and design preferences of the home. Working closely with a qualified plumber can help homeowners navigate these important considerations.
Tip: Use insulation blankets to improve energy efficiency
