What Size Tankless Water Heater Do I Need?

Choosing the right size tankless water heater for your home is crucial to ensure you have enough hot water to meet your daily needs. A tankless water heater can be a small home upgrade with major benefits – as long as it’s sized and installed correctly. If you’re asking, “What size tankless water heater do I need?” the answer depends on two key factors: flow rate and temperature rise. Let’s break down these factors so you can make an informed decision and get the most out of your investment.

Of course, there’s no need to reinvent the wheel. A plumber certified by one of the two leading tankless brands, Rinnai or Navien, could quickly answer this question for you. Your plumber will be able to recommend proper placement of your tankless, talk with you about recirculation options, and ensure your home will allow for a safe, code compliant installation. At Aaron Services: Plumbing, Heating, Cooling, we provide free tankless consultations daily.

Your plumber will consider the following to determine what size tankless water heater you need:

Flow Rate (GPM)

The flow rate is the amount of hot water you’ll need at any given time, measured in gallons per minute (GPM). To calculate this, consider how many fixtures (like showers, faucets, or dishwashers) will be using hot water at the same time. For example:

Add up the GPM for each fixture you expect to use simultaneously to determine the total flow rate. For a home with two bathrooms, running two showers at once may require at least 5 GPM.

Temperature Rise

The next factor to consider is temperature rise, which is the difference between the incoming water temperature and the desired hot water temperature. For instance, if your incoming water temperature is 50°F and you want it heated to 120°F, you’ll need a tankless water heater that can handle a 70°F temperature rise. Homes in colder climates will typically require more powerful units to achieve this rise.

Typical Tankless Water Heater Sizes

• For a home with 1 bathroom, a 6-7 GPM tankless water heater is usually sufficient.
• For a home with 2 bathrooms, an 8-9 GPM unit is typically recommended.
• Homes with 3 or more bathrooms may require a 9-11 GPM unit to ensure adequate hot water supply during peak usage times.

These units are especially effective when powered by gas, as gas tankless water heaters tend to provide higher flow rates and handle larger temperature rises better than electric models.

What Other Considerations Should I Make to Determine What Size Tankless Water Heater I Need?

When choosing the right size tankless water heater, there are several other factors to keep in mind:

Venting Requirements

Gas tankless water heaters require proper venting to safely expel combustion gases. Make sure your home has the necessary ventilation setup, or be prepared for modifications during installation.

Gas Meter and Gas Line Size

A tankless gas water heater demands a larger gas supply than traditional units. Your gas meter and gas line must be sized appropriately to handle the increased demand. Many tankless units require a ¾-inch gas line to ensure proper operation, so you may need to upgrade your current system if it’s not sufficient.

Installation

Tankless water heaters are more complex than traditional storage tank models, making professional installation essential. A certified and experienced plumber can ensure that your system is installed properly, so you can avoid common issues like incorrect venting or gas line sizing.

Reputable Tankless Water Heater Brands

When choosing a tankless water heater, it’s also important to go with a trusted brand. Two of the most highly recommended brands are Navien and Rinnai.

• Navien units are known for their efficiency, with many models featuring built-in recirculation systems that reduce the wait time for hot water. They offer energy savings and top-quality performance.
• Rinnai is another reputable brand offering reliable and long-lasting units. Known for their quiet operation and strong warranties, Rinnai tankless heaters are designed to provide years of dependable hot water.

Recirculation Systems for Instant Hot Water

For homeowners who want instant hot water, some tankless water heaters come with recirculation systems. These systems keep hot water circulating through your pipes, so you don’t have to wait for the water to heat up. Some models from Navien and Rinnai even come with built-in recirculating pumps, providing both endless hot water and instant access to hot water with minimal wait time.

The Importance of Hiring a Certified Plumber

While it’s important to choose the right size tankless water heater, it’s equally crucial to hire a certified, experienced plumber to install it. Tankless water heaters are sophisticated systems that require precise installation. Even plumbers with years of experience may not fully understand the intricacies of these units. A poorly installed tankless system can lead to frequent issues, from insufficient hot water to costly repairs.

At Aaron Services, we specialize in tankless water heater installations and have the experience to ensure your system operates smoothly from day one. Choosing the right plumber can be the difference between endless hot water and endless headaches.

If you’re still wondering, “What size tankless water heater do I need?” contact us today for a consultation. We’ll help you choose the right size for your home and ensure a seamless installation. With Aaron Services, you’ll get expert advice, quality service, and a tankless water heater that’s built to last.