Can Tankless Water Heaters Get as Hot as Conventional Tank Water Heaters?

 

Many homeowners considering the switch from a conventional tank-style water heater to a tankless (or on-demand) water heater often ask one major question: Can tankless water heaters provide water that’s just as hot as traditional tank models?

The short answer is yes—but there’s more to it than simply matching temperature numbers. In this post, we’ll explore how tankless systems measure up in performance, what factors affect their heating capacity, and how to ensure you get the right unit for your home’s needs.

How Do Tankless and Tank Water Heaters Compare in Temperature?

Conventional Tank Water Heaters: Most tank water heaters maintain a set temperature, typically around 120°F, and store hot water ready for use. Because they hold hot water in reserve, these systems don’t need to "heat up" on demand but rely on a tank size to ensure a constant supply.

Tankless Water Heaters: Tankless water heaters, on the other hand, don’t store hot water. They heat water as it passes through the system, often with adjustable thermostats ranging from 100°F to 140°F. However, achieving high temperatures consistently depends on several variables, such as water flow rate and incoming water temperature.

Key Factors Affecting Tankless Water Heater Performance

1. Climate and Water Supply Temperature
   Tankless water heaters are rated by the rise in water temperature they can produce. For instance, in a colder climate like Chicago, where the incoming water temperature may be as low as 40°F, a tankless water heater will need to work harder to reach the same hot water temperature compared to warmer climates like Arizona, where the incoming water may be 70°F. This variation directly affects the efficiency and output of tankless models.

2. Sizing the Unit for Your Household
   Unlike tank models that store hot water, a tankless system's ability to deliver hot water depends on its flow rate. A larger household with multiple simultaneous water demands (e.g., showers, dishwashers, and washing machines running at the same time) will need a larger unit or possibly multiple units to maintain the desired temperature. Incorrect sizing can lead to issues with water not being as hot when multiple sources are in use.

   Expert Tip: To avoid temperature drops, calculate your household’s peak water demand and ensure the unit can handle the gallons-per-minute (GPM) required.

Efficiency: Tankless vs. Tank Water Heaters

One of the biggest advantages of tankless systems is their energy efficiency. Since they only heat water when needed, they can save significant energy over time, especially when sized correctly. This is in contrast to tank models, which continuously expend energy to keep stored water hot.

However, in colder climates, where more energy is required to heat the incoming water, the efficiency benefits may slightly decrease due to the heater working harder. It’s important to balance energy savings with performance needs by ensuring your tankless system is appropriately sized.

Do You Need a Larger Tankless Water Heater in Cold Climates?

In colder regions, such as the Midwest or the Northeast, a tankless water heater needs a higher BTU (British Thermal Unit) rating to compensate for the colder incoming water temperatures. The difference in the temperature rise required is significant. For instance, in Chicago, where the water temperature might be 40°F, the heater needs to increase the water temperature by at least 80°F to provide 120°F hot water.

In contrast, someone in a warmer region like Florida may only need a 50°F rise. Homeowners in colder climates should look for models specifically rated for high temperature rise or consider hybrid systems that combine the best of both tank and tankless technology.

The Importance of Professional Installation and Maintenance

Installing a tankless water heater can be more complex than a traditional tank system due to its higher gas or electric power requirements, especially for larger units. A professional installer will ensure the unit is sized correctly, vented properly, and meets all local building codes. Additionally, regular maintenance, including descaling, is crucial in areas with hard water to prevent mineral buildup and maintain efficiency.

Tankless Water Heaters: The Right Choice for Your Home?

Choosing between a tankless and conventional water heater depends on various factors, including climate, household water demand, and your long-term energy goals. Tankless systems are highly efficient and space-saving, but they require careful consideration when it comes to sizing and climate.

What's Next?

Both tankless and conventional water heaters can provide ample hot water for your household, but the key lies in selecting the right system for your unique needs. If you’re unsure which water heater is best for you, consider consulting with an expert to assess your home’s water heating requirements.

For personalized advice, feel free to contact ABC Plumbing, Sewer, Heating, Cooling and Electric if you live in Illinois and ABC Plumbing, Air & Heat if you live in Florida. We’re here to help you make the best choice for your home.

Also check the following blog post: What's the Purpose of a Water Heater Expansion Tank?