how to choose the right size tankless water heaterChoosing a tankless water heater that is the correct size for your needs is probably the most important part of the process. The promise of a tankless water heater is that you get unlimited hot water, in a way that is energy efficient. Choose a tank that is too small, and you won’t feel like you have unlimited hot water at all. Instead, it’ll be kind of cold sometimes. Here’s what you need to understand to choose the right size tankless water heater and a quick guide on how to get it right the first time.

Understand Tankless Water Heaters

Why do you even need to choose a tankless water heater size? Don’t they just heat up enough water for you to use once you demand it? That’s not quite how it works, and understanding how will help you pick a tankless water heater that is the right size for your family.

Tankless water heaters can continuously produce hot water. That’s why they don’t have a tank. They simply take the water in your pipes and heat it up on demand. However, they can only heat up so much water every minute. All tankless water heaters will have a GPM, gallons per minute, rating. This is how many gallons of hot water they produce a minute. Most are between two and five gallons per minute. If you choose a model that produces two gallons, but then you run enough fixtures to require five gallons, you’ll get lukewarm water at best and be pretty disappointed. That said, tankless water heaters that produce more GPM are more expensive, so you don’t want to buy one that produces much more than you need.

You need to choose the right size. Here’s how.

Choose the Right Size

Calculating your peak hot water needs is essential to choose the right tankless water heater. What does peak needs mean? It means the most hot water you’ll demand at once. We suggest you observe your household for a day or more and find the time when the most fixtures, appliances, or other plumbing features are demanding hot water. Then you simply have to add up how many gallons those fixtures uses. This number is how much your tankless water heater should generate.

For example, in your home you might have one person running the shower while you run the dishwasher and someone else turns the washing machine onto a “hot” cycle. You’d then need to add up the gallons per minute of the shower head, the dishwasher, and the washing machine.

Note that if your peak use adds up to significantly more than the tankless water heater you want to buy, you could make some changes to keep your use under the water heater’s GPM. Using the washing machine on cold or delaying the dishwasher until nighttime are good options.

Check with Your Plumber

Your plumber in Discovery Bay or beyond, is your best source of information on your tankless water heater and the size that you should choose. Talk to them about what size you think you need and see if they agree.