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10 Factors to Consider in Choosing a Tankless Water Heater

Updated on:
May 2, 2024
Factors to Consider in Choosing a Tankless Water Heater

Image Source: Canva

You're in the market for a tankless water heater, but with numerous options, how do you decide? It's not as simple as picking the sleekest model.

Careful consideration of daily hot water usage, installation environment, water source quality, unit capacity, fuel type, energy efficiency, safety features, durability, regulatory compliance, and even aesthetics can guarantee you choose a unit that's tailored to your specific needs, meets demand, operates safely, and complies with local regulations. 

Intrigued? Let's explore these factors further.

Application Specific Needs

When selecting a tankless water heater, the first vital step is to analyze your specific hot water needs based on your daily usage and the number of users. You've got to be clear about what you're using your hot water for. Is it for a family of four or a bustling restaurant? Maybe there are twelve folks on a bus you're accommodating? Each scenario demands a different capacity.

Rather than focusing solely on the cost, it's important to match the unit's size to your needs. You don't want to end up with an undersized unit that can't keep up, or an oversized one that's wasting energy. As such, you've got to pick a heater that's tailored to your hot water usage patterns and the number of users.

Installation Environment

Having settled on your specific hot water needs, it's important to take into account the environment where your tankless water heater will be installed. The installation environment can impact both the performance and lifespan of the unit.

For instance, if the unit is installed outside, it needs to withstand weather conditions. If it's in a small, enclosed space, adequate ventilation is essential to prevent overheating. The proximity to your power source, whether it's gas or electricity, is important to take into account for practical and safety reasons.

Also, think about the ease of access for future maintenance or repairs. Lastly, local regulations may dictate certain installation requirements. So, make sure you're aware of those before buying.

Water Source and Quality

Next, you'll need to take into account the quality and source of your water, as this can greatly impact the type of tankless water heater you should choose. If you're using city water, it's likely treated and consistent in quality, making it less likely to cause issues with your heater.

Yet, if you're relying on well water, the mineral content can be higher, which may lead to scale build-up, affecting the heater's performance and lifespan. To combat this, you might need a water softener or a unit designed to handle hard water.

Additionally, consider the water temperature at its source. Colder incoming water requires more energy to heat, which could influence your choice of a gas, propane, or electric model.

Unit Capacity and Size

Focusing on the unit's capacity and size is vital as it determines whether the water heater can meet your regular hot water demand. You'll want to make sure the unit can handle the volume of water you need, especially during peak times. If you frequently take long, hot showers or wash large amounts of dishes, you'll require a unit with a higher capacity.

Size is also an important factor. Tankless heaters are compact, but they still require installation space. You'll need to think about where you're going to fit it.

Don't overlook these elements. They directly impact the heater's efficiency and your comfort. Picking the right capacity and size ensures you won't be left in the cold during your morning shower.

Fuel Type and Availability

After securing a water heater with the right capacity and size for your needs, you'll want to evaluate the fuel types available for your unit. Fuel type is an essential factor as it directly impacts the heater's operation and your convenience.

Common fuels used include propane, natural gas, electric, and diesel. Each type has its pros and cons. For example, while propane and natural gas are often cheaper and more efficient, they mightn't be readily available in all areas. Electric heaters, conversely, are universal but might be more expensive to operate.

Consider your location and the availability of these fuels before making your decision. Remember, your choice should provide a balance between practicality and cost-effectiveness.

Energy Efficiency and Operating Costs

It's important to take into account the energy efficiency and operating costs of your potential tankless water heater. An efficient model, while pricier initially, can save you money in the long run. Efficiency is usually measured by the Energy Factor (EF), a higher EF indicates a more efficient heater.

Also, consider if the heater qualifies for Energy Star, an international symbol for energy efficiency. You should also estimate operating costs which include the cost of fuel and maintenance. More efficient heaters typically have lower operating costs.

Safety Features

While you're crunching the numbers on energy efficiency and operating costs, don't overlook the importance of safety features in your potential tankless water heater. High-quality safety features don't just offer peace of mind, they also protect your home and family.

Look for models with overheating protection to prevent potential scalding. Essential safety devices are important, too, shutting off the fuel supply if the flame goes out unexpectedly. An anti-freeze feature can protect your unit in colder climates. Additionally, a pressure relief valve is key for managing pressure within the system, and avoiding possible explosions.

Image Source: Canva

Durability and Maintenance

When selecting a tankless water heater, you should also take into account its durability and the maintenance it requires. A sturdy unit will stand the test of time, reducing the need for costly replacements. Look for models built with high-quality materials to guarantee longevity.

You'd be wise to factor in the ease of maintenance too. Heaters with easy-to-replace parts require less effort when routine upkeep is needed. It's also advantageous to choose a brand that offers local service for more complex issues.

Regular maintenance doesn't just prolong the lifespan of your heater, it also ensures top-notch performance. Therefore, a balance of durability and manageable maintenance guarantees your investment provides continuous hot water without becoming a persistent headache.

Regulatory and Compliance Issues

You should also make sure your chosen tankless water heater complies with local codes and regulations, as these can impact not only the installation process but also its operation and efficiency. 

Non-compliance can result in fines, legal issues, and even unsafe conditions. Check if your model meets safety standards, such as those set by Underwriters Laboratories (UL) or the American National Standards Institute (ANSI).

You'll also want to verify that it's certified for use in your specific location, as some regions have unique requirements. Make sure the unit's emission levels are within permitted levels to protect your household and environment. Finally, ensure it complies with Energy Star criteria for energy efficiency.

Regulatory compliance isn't just about avoiding penalties - it's about ensuring safety and peak performance.

Aesthetic and Space Considerations

Take into account the aesthetic appeal and space requirements of the tankless water heater for your home. Unlike bulky traditional units, these heaters are compact, freeing up valuable space. That being said, they're not always the most attractive appliances.

If you're tight on space or concerned about the heater clashing with your decor, think about its location and visibility. Some units can be tucked away in a utility closet or garage, while others might be more visible.

You'll also want to think about the installation process. Will it involve significant alterations to your home? These are all aspects you need to keep in mind. Remember, while functionality is essential, you shouldn't overlook the impact of aesthetics and space on your overall satisfaction.


In sum, choosing the perfect tankless water heater isn't a one-size-fits-all scenario.

You've got to take into account your specific needs, installation environment, water quality, unit capacity, fuel type, safety features, durability, regulatory compliance, and even aesthetics.

It's all about finding the perfect balance that suits your environment, meets your water usage requirements, guarantees safety, and is also cost-effective.

So, take your time, analyze these factors, and make a well-informed choice.

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