What Size of Tankless Water Heater Do I Need? Get Them Answered Here!

The highest temperature rise you may achieve at a certain flow rate is used to rate tankless water heaters. Therefore, you must ascertain the flow rate and temperature rise you’ll require to size a demand water heater for your home’s application (the entire house or a distant use, such as only a bathroom).

So, what size of tankless water heater do I need? It’s crucial to remember that under-sizing your tankless water heater is never a good way to save money.

What Size of Tankless Water Heater Do I Need?

The per-minute flow rate of tankless water heaters is compared to standard hot water tanks instead of their gallon capacity, recovery rate, and first-hour rating. Most major brands’ typical flow rates fall between 4 and 12 gallons per minute (GPM). Take into account these typical hot water demands and the necessary flow rates for each:

  • Dishwasher 0.5 – 1.0 GPM
  • Bathroom sink 0.5 – 1.5 GPM
  • Kitchen sink 1.5 – 2.0 GPM
  • Utility sink 1.5 – 2.0 GPM
  • Washing Machine 2.0 – 2.5 GPM
  • Shower 1.5 – 2.5 GPM
  • Bathtub 2.5 – .0 GPM
  • Jacuzzi/Hot tub 4.0 – 5.0 GPM
what size of tankless water heater do i need

To establish the maximum flow rate necessary, consider how many of these demands you could have. For example, we advise 6-7 GPM for a house with a single bathroom, 8–9 GPM for a home with two bathrooms, and 9–11 GPM for a house with three or more bathrooms.

The question of “what tankless water heater do I need?” based on our experience has shown that smaller 4-5 GPM units work well for studio flats, small residences with one bathroom, and other application-specific requirements. There are more alternatives for big homes, like connecting many tankless units in series.

Tankless Water Heater Size Calculator

Once you have purchased a tankless water heater, you must choose the size you need.

  • Tankless Water Heater Size for a Family Of 5

We wish there were a more straightforward solution, but you need to use the calculator to determine your unique requirements.

Your tankless size will depend on your location, how many fixtures will be used at peak times, and whether you will run laundry or other appliances.

However, it’s safe to state that you’ll have to get a bigger tankless heater. Most of the time, you’ll require a tankless heater with a minimum of 7 GPM output.

  • Tankless Water Heater Size for a Family of 4

One of the most often asked topics is how big a tankless water heater you need for a large household. For example, a family of three will require a smaller tankless water heater than a family of five. But, on the other hand, home of four will require around 8-10 GPM and a tankless water heater rated at 20–28 kW.

Installing & Maintaining a Tankless Water Heater

Now that you have the question answered, you ought to know how to maintain them:

  1. Fuel Type

You can install a gas tankless water heater if you presently have a gas tank water heater (natural gas or propane). However, the gas connection from your meter to your heater will likely need to be upgraded, as tankless heaters frequently need a dedicated line to handle their high needs of up to 200,000 BTU.

If you already use an electric water heater, you need to connect an existing gas connection to your water heater setup or apply gas or propane service to your house. Switching to gas tankless is a terrific option and an excellent opportunity to take advantage of these rebates, which some utility providers give multiple refunds for doing so.

Electric tankless water heaters do not provide good feedback, do not provide a favorable temperature, or have sufficient flow capacity.

  1. Location

Choosing the ideal location for your tankless water heater is crucial to save space and have the lowest installation expenses. Discuss with your installer the perfect place for a tankless water heater in your house.

Also, take into account the fact that the device will require reliable electricity. Remember that the device won’t deliver hot water if the power goes off.

However, if you wish, installers can build a battery backup system. Before starting work in your house, your installer should discuss the current plumbing rules and permit charges with you to estimate the overall cost of installing a tankless water heater.

Make sure you comprehend the criteria to secure your water heater installation. Additionally, ask “what size of tankless water heater do I need?” to your installation to explain how to maintain a tankless water heater regularly.

Despite the minimal maintenance cost, certain manufacturers advise descaling, the frequency of which will depend on the caliber of the water in your area. This will increase the lifespan of your tank. The owner’s handbook in your vehicle might provide you with more advice.

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Heater Technician is a skilled author and water heater expert with years of experience in the field. He has authored several articles and books on various aspects of water heater installation, maintenance, and repair.