What Size Electric Tankless Water Heater Do I Need: A Comprehensive Guide to Sizing and Beyond

When it comes to choosing the right electric tankless water heater, the question of size is paramount. But what does “size” really mean in this context? Is it about physical dimensions, or is it more about the capacity to meet your household’s hot water demands? Let’s dive into the intricacies of sizing an electric tankless water heater, and explore some related considerations that might not follow a strict logical sequence but are nonetheless important.
Understanding the Basics of Electric Tankless Water Heaters
Electric tankless water heaters, also known as on-demand water heaters, provide hot water only when it’s needed. Unlike traditional tank water heaters, they don’t store hot water, which eliminates standby heat loss and can lead to energy savings. However, the key to their efficiency lies in selecting the right size for your home.
Determining the Right Size
The size of an electric tankless water heater is primarily determined by two factors: flow rate and temperature rise.
Flow Rate
Flow rate is measured in gallons per minute (GPM) and refers to the amount of hot water the heater can deliver at any given time. To determine the required flow rate, you’ll need to consider the number of fixtures (like showers, sinks, and appliances) that might be using hot water simultaneously.
Temperature Rise
Temperature rise is the difference between the incoming cold water temperature and the desired hot water temperature. This varies depending on your geographic location and the time of year. For example, if the incoming water temperature is 50°F and you want your hot water at 120°F, the temperature rise needed is 70°F.
Calculating Your Needs
To calculate the size of the electric tankless water heater you need, follow these steps:
- List All Hot Water Fixtures: Identify all the fixtures in your home that use hot water.
- Determine Flow Rates: Find out the flow rate for each fixture. This information is usually available in the product specifications.
- Calculate Total Flow Rate: Add up the flow rates of all fixtures that might be used simultaneously.
- Determine Temperature Rise: Measure the incoming water temperature and decide on the desired hot water temperature.
- Select a Heater: Choose a heater that can handle the total flow rate and provide the necessary temperature rise.
Additional Considerations
While the above steps provide a solid foundation for sizing your electric tankless water heater, there are other factors to consider:
Energy Efficiency
Electric tankless water heaters are generally more energy-efficient than their tank counterparts. However, the efficiency can vary between models. Look for units with a high Energy Factor (EF) rating.
Installation Requirements
Electric tankless water heaters require a significant amount of electrical power. Ensure your home’s electrical system can support the unit you choose. You may need to upgrade your electrical panel or wiring.
Maintenance
Regular maintenance is crucial for the longevity and efficiency of your electric tankless water heater. This includes descaling to remove mineral buildup, especially if you live in an area with hard water.
Cost
While electric tankless water heaters can save you money on energy bills, the initial cost can be higher than traditional tank heaters. Consider the long-term savings versus the upfront investment.
Environmental Impact
Electric tankless water heaters have a smaller carbon footprint compared to gas models, especially if your electricity comes from renewable sources.
Related Q&A
Q: Can I install an electric tankless water heater myself? A: While it’s possible for a skilled DIYer to install an electric tankless water heater, it’s generally recommended to hire a professional. This ensures the installation is done safely and complies with local codes.
Q: How long do electric tankless water heaters last? A: With proper maintenance, electric tankless water heaters can last 20 years or more, significantly longer than traditional tank water heaters.
Q: Are electric tankless water heaters suitable for large families? A: Yes, but you’ll need to choose a unit with a high flow rate to accommodate multiple simultaneous uses. It’s also important to ensure your electrical system can handle the demand.
Q: Do electric tankless water heaters work during a power outage? A: No, electric tankless water heaters require electricity to operate. If you live in an area prone to power outages, consider a backup power source or a different type of water heater.
Q: Can I use an electric tankless water heater for my entire home? A: Yes, but you’ll need to size it correctly to meet the hot water demands of your entire household. In some cases, multiple units may be necessary to ensure adequate hot water supply.
In conclusion, selecting the right size electric tankless water heater involves careful consideration of your household’s hot water needs, energy efficiency, installation requirements, and long-term costs. By taking the time to understand these factors, you can make an informed decision that ensures a reliable and efficient hot water supply for your home.