It's 07:24 AM on and we're open!

What Size of Tankless Water Heater Do I Need

Are you tired of running out of hot water while in the middle of a shower? Or perhaps you’re looking for a way to save on energy costs. Whatever the reason may be, switching to a tankless water heater can provide you with a nearly endless supply of hot water while being energy efficient. However, it’s important to find the right size for your home. Here’s how to determine the correct size of tankless water heater for your household.

Consider the Flow Rate

The most important factor in determining the correct size of a tankless water heater is its flow rate. This is the amount of hot water the heater can produce per minute. A 3.2 gallons per minute (gpm) tankless water heater can provide enough hot water for a shower and a sink, making it a good option for smaller households. However, if you have a larger household, you will need a higher flow rate.

Add up the flow rate for all the fixtures you expect to use at the same time. For instance, if you have two showers and a sink that you expect to use at the same time, you would need a 5.75 gpm unit based on two 2.5 gallon-per-minute showers and one 0.75 gallon-per-minute faucet.

Calculate the Required Heating Capacity

In addition to the flow rate, you should also consider the heating capacity of the tankless water heater. This is the amount of heat that the unit can put into the water. To determine the required heating capacity, subtract the incoming water temperature from the desired temperature.

For example, if the water coming into your home is at 60 degrees Fahrenheit and you want to heat it to 120 degrees Fahrenheit, you will need a tankless water heater that can add 60 degrees of heat. However, keep in mind that in winter, the water temperature can drop lower than 60 degrees Fahrenheit, and you may need to add 75 or 80 degrees of heat to reach your desired temperature. Therefore, make sure the tankless water heater you purchase can provide enough heat for your desired temperature and flow rate.

Factors to Consider

When choosing a tankless water heater, there are other factors to consider, such as the fuel source. Tankless water heaters can be powered by electricity, natural gas, or propane. Electricity may be the easiest option if you don’t have access to natural gas or propane, but it may be more expensive to operate. Natural gas and propane are often more efficient and may cost less to operate, but they require proper venting and may not be available in all areas.

It’s also essential to have a professional install your tankless water heater. Proper installation can ensure that your unit operates safely and efficiently.


Switching to a tankless water heater can provide you with a constant supply of hot water and energy efficiency. When determining the correct size of tankless water heater for your household, consider the flow rate and the heating capacity needed to reach your desired temperature. Additionally, consider the fuel source and have a professional install the unit for optimal performance. With the right tankless water heater, you’ll never have to worry about running out of hot water again.

If you’re considering switching to a tankless water heater, let Guardian Plumbers help you find the perfect size and fuel source for your household. Our team of professionals can provide expert installation and ensure that your unit operates safely and efficiently. Contact us today to schedule an appointment!

Schedule an Estimate Today
Why Choose

Guardian Plumbing?

  • Exceptional Customer Service
  • Unbeatable Prices
  • Satisfaction Guaranteed
  • Certified, Reliable Technicians
  • 24/7 Emergency Availability

Professional & Comprehensive

You can trust that our Riverside County plumbing company will only provide the highest quality customer service with a commitment to professionalism and helping you, no matter how big or small your issue may be. We back up all our workmanship with a comprehensive warranty and always strive to go above and beyond your expectations. We will be there when you need answers and always explain your options without trying to upsell you.

What Our Customers Are Saying!

Everyone I spoke to was courteous informative and made an emergency situation where my ceiling was leaking a lot less stressful and I very much appreciate that.

- Kathryn S.

These guys are AWESOME I’ve used them about 10 times now for random Plumbing things and will NEVER call anyone else great customer service honest quotes and great rates thanks for being awesome guys.

- Jon F.

Guardian Plumbing is very professional, they answer your questions and very knowledgeable. They also walk you through of what they’re going to do.

- Maria G.

As regular customers for our house and Rental Properties Guardian Plumbers always provides great customer service, prompt repairs at a great price with excellent work.

- Scott E.
Left Quote
Right Quote