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How to choose a Tankless Water Heater for your home, your needs, and your budget.

A tankless water heater

Congratulations on deciding to buy a tankless water heater for your home! Now, how do you choose the right one for your home and your budget? Petro is here to help you sort through the choices that will help you decide on the right tankless hot water heater for your needs.

First, out of all the solutions for heating water for your home, choosing a tankless water heater is perhaps the best way to help you save on utility bills over the course of a year.

Whether you choose to go with a gas-powered tankless water heater or an electric tankless water heater, you are set to save between approximately $40 to $100 a year in energy costs according to the U.S. Department of Energy.

It’s also important to know that tankless water heater installations are generally more expensive than their tank-bound counterparts, but the energy savings over the years will pay for the additional upfront costs.

There are many considerations when choosing whether to purchase a tankless water heater, and which type. This provides an overview of those considerations and, as always, your team of experts at Petro is here to guide you through any questions.

Determine the maximum number of devices.

Tankless models ready for installation

One of the most important considerations when thinking about tankless water heaters is how many units you will need in your home.

This is based on your average hot water usage, which is a function of how many people are using hot water in your home. For instance, if there are ten people in your home you may need more than one unit. But, if you live alone, or only have one other person, then one hot water heater unit might be fine for your needs.

Petro’s experienced technicians have worked for years in the water heater industry. This means our professionals will be able to correctly determine how many tankless water heaters you will need in your home.

Determine the required temperature rise.

Washing machine using hot water from a tankless water heater

The next most important factor when choosing a tankless hot water heater is how well it heats water to the required temperature. In the industry, we call this ‘temperature rise’.

Determining the correct temperature rise capabilities for your tankless water heater requires some information about your home. Perhaps the most important factor is the average temperature of the water coming into your home.

The most common hot water usage is showering, which usually runs between 101-105 degrees Fahrenheit. Determining the right temperature rise factor for your tankless water heater is a calculation based on the incoming temperature of the water. For example, if the incoming water temperature is at 40 degrees, you’ll want a tankless water heater with a temperature rise factor of about 60 degrees.

You can find out your average water temperature with various online heat map tools; Petro can easily assist you in determining it, too. Heat maps give you a general idea of the temperature of incoming water, which helps you choose the right tankless water temperature. In warmer climates, you’ll need a less powerful tankless water heater. In colder climates, a unit with a higher temperature rise factor will be required.

As our tankless water heater technicians have extensive experience in their service areas, Petro can help you figure out right away which type of unit will work for your home.

Determine the right size.

Hot water from a shower head

Figuring out how to choose the right size of a tankless water heater can be a challenge. You need to determine how much hot water you are using, while also understanding the required temperature rise for your home appliances.

This is because it takes time to heat up water. The greater your temperature rise need, the larger the unit. A larger unit is also needed if there are several people using hot water, or if you plan to have several appliances running at once.

Flow rates.

An important factor for determining the right size of a tankless water heater is knowing how much water and at what temperature various appliances use hot water. Here’s a handy guide for the average temperature and flow rates (measured in gallons-per-minute, or GPM).

  • Bathtub Flow Rate - Bathtubs have an average flow rate of four gallons per minute, at a temperature of 102 degrees.
  • Shower Flow Rate - Showers have an average flow rate of 2.5 to three gallons per minute, at a temperature of 104 degrees.
  • Washing Machine Flow Rate - Washing machine flow rates average at two gallons per minute, at an average temperature of 120 degrees.
  • Dishwasher Flow Rate - Dishwashers have an average flow rate of 1.5 gallons per minute, with an average temperature of 110 degrees.
  • Kitchen Sink Flow Rate - Kitchen sinks have an average flow rate of 1.5 gallons per minute, with an average hot water temperature of 110 degrees.

Select the power source - Natural gas, propane or electric.

Bathroom using water from a tankless water heater

Tankless water heaters use three different types of power sources – natural gas, propane or electric.

If you are considering using any electric-powered appliance, you must determine how it will impact the power usage of your home overall. Some older homes might have weaker electric systems. This means that a whole-house electric tankless water heater may not be the best option, as it might overload an older system.

Natural gas- and liquid propane-powered tankless water heaters are, on average, more powerful than electric units. For this reason, they are most often used as a whole-house solution for hot water needs.

Additionally, natural gas and liquid propane tankless water heaters are far more energy-efficient. The U.S. Department of Energy has determined that electric units save you about $40 a year in energy costs, while natural gas and liquid propane units save about $100 annually.


As with any high-usage appliance, maintenance is a crucial consideration when thinking about having a tankless water heater in your home.

Petro Home Services recommends that you have your tankless water heater serviced annually. This helps you achieve the longer life expectancy of these units over tank-bound units. Experienced technicians will change the air filter and make sure the burner is in working order.

Additionally, mineral buildup, in areas with hard water, is detrimental to any water heater. Using vinegar to remove mineral buildup, which we call “scale”, every 500 hours is crucial to keeping your unit running smoothly year-round.

Proper maintenance for any water heater, whether using a tankless unit or otherwise, is best done by experienced technicians. Our team of experts can help determine the proper maintenance regimen you need for your home, no matter where you live.

Whether you’re looking for hot water heater troubleshooting tips or want to know when it might be time to upgrade or replace your water heater, the experts at Petro Home Services have the answers.

We’re here to help.

At Petro Home Services, we understand how to keep your home running smoothly all year round. With many years of experience, dealing specifically with tankless water heaters, you can rest assured that Petro will keep your unit running well for its full life expectancy. Plus, you will have reliable hot water and energy savings for years to come.

Contact Petro Home Services today at 800.645.4328 to find out how to choose the right tankless waterheater, keep your hot water running, and save money on your home utility bills.

Petro Home Services is proud to not only serve communities in DC, CT, MA, MD, NJ, NY, PA, and RI but we also proudly acknowledge the skills and experience of our expert team behind all resources. With insights on topics ranging from heating oil facts to common air conditioning questions, you can rely on Petro Home Services for facts and information to help you understand more about your heating, cooling and home comfort needs. This article and all articles on the Petro Home Services website have been approved by our team of home service experts.