How to Properly Size a Tankless Water Heater for Your Home's Needs

Tankless water heaters have become increasingly popular in recent years due to their energy efficiency and convenience. Unlike traditional water heaters that store and heat a large amount of water in a tank, tankless water heaters heat water on demand, providing hot water only when needed. This not only saves energy but also frees up space in your home. However, choosing the right size tankless water heater for your household can be a daunting task. In this post, we'll guide you through the factors to consider and steps to take to properly size a tankless water heater for your home's needs.

1. Determine your household's hot water demand

The first step in sizing a tankless water heater is to determine your household's hot water demand. This includes the number of people in your household, the number of bathrooms, and the typical hot water usage patterns. For example, a family of four with two bathrooms will have a higher hot water demand than a single person living in a studio apartment. To get an accurate estimate of your hot water demand, you can use a sizing calculator or consult with a professional plumber.

2. Calculate the flow rate

Once you have determined your hot water demand, you need to calculate the flow rate. The flow rate is the amount of hot water your household uses at any given time. To calculate the flow rate, you need to add up the flow rates of all the hot water fixtures in your home, such as showers, faucets, and appliances. The flow rate is measured in gallons per minute (GPM). For example, a showerhead typically has a flow rate of 2.5 GPM, while a dishwasher has a flow rate of 1.5 GPM.

3. Choose the right size tankless water heater

Now that you have determined your hot water demand and flow rate, you can choose the right size tankless water heater for your household. Tankless water heaters are rated by their maximum flow rate, measured in GPM. You need to choose a tankless water heater that can meet your household's peak hot water demand. For example, if your household's peak hot water demand is 5 GPM, you need to choose a tankless water heater with a minimum flow rate of 5 GPM.

4. Consider the temperature rise

Another factor to consider when sizing a tankless water heater is the temperature rise. The temperature rise is the difference between the incoming cold water temperature and the desired hot water temperature. The higher the temperature rise, the more powerful the tankless water heater needs to be. For example, if the incoming cold water temperature is 50°F and the desired hot water temperature is 120°F, the temperature rise is 70°F.

5. Consult with a professional plumber

Sizing a tankless water heater can be a complex process, and it's important to get it right to ensure that you have enough hot water for your household's needs. If you're unsure about how to properly size a tankless water heater, it's best to consult with a professional plumber. A plumber can assess your household's hot water demand, flow rate, and temperature rise and recommend the right size tankless water heater for your home.

In conclusion, sizing a tankless water heater requires careful consideration of your household's hot water demand, flow rate, and temperature rise. By following the steps outlined in this post and consulting with a professional plumber, you can choose the right size tankless water heater for your home's needs and enjoy the energy efficiency and convenience that it provides.