How Many Amps Does a Gas Tankless Water Heater Use?

A water heater is one of the most important appliances you can get for your home. It can provide you with an unlimited hot water supply, thus very convenient.

Tankless water heaters don’t take up a lot of space, give hot water on demand, and are highly efficient. With one, you can save up to 50% on your monthly energy bill.

However, you need to know the basics, including how many amps the water heater draws. This will help you avoid overloading your home’s electrical system.

So, how many amps does a gas tankless water heater use? A gas tankless water heater requires a minimal electrical connection. Check for the installation requirements when buying the model.

How Many Amps Does a Water Heater Use?

Understanding the number of amps a water heater draws is vital. It will help you decide on what model to settle for.

The amount of amperage a water heater uses depends on the following:

  1. Heater type
  2. Capacity
  3. Fuel type
  4. Energy Efficiency
  • Heater Type: Tank or Tankless

There are 2 types of water heaters: with a tank and tankless. Models with tanks are the oldest and are also known as container or storage heaters.

The tank stores water that is continuously heated, awaiting use. Tank water heaters require fewer amps than tankless models.

However, they might need more power as they are continuously heating the water.

Tankless water heaters, also known as on-demand heaters, are the most recent designs. Since these models only run when there’s a need, they draw less power depending on the amount used.

  • Capacity

A water heater is only helpful if it provides you with enough hot water when you need it.

Whether with a tank or tankless, if it doesn’t have the suitable capacity to meet your household’s water demands, you don’t need it.

Tank water heaters have come with 20 to 80-gallon size tanks. The bigger the tank, the more amps it’ll draw to heat the water.

The capacity of tankless heaters is calculated by flow rate or gallons per minute. The higher the flow rate, the more amps it will draw.

Note that although choosing a unit with the largest capacity might sound appealing, it may require more amps than your home can accommodate.

  • Fuel Type: Electric or Gas

The fuel a water heater uses affects the amount of power it requires to run effectively. Electric models are more expensive than natural gas models.

Electric heaters are also easy to install, unlike gas heaters, which require attachment to a gas line. There will be added expenses when installing a gas water heater for the first time.

  • Energy Efficiency

How efficiently your water heater uses energy will affect the amps it uses. The more energy-efficient a unit is, the more amps it’ll draw.

However, although a more energy-efficient heater might require more amperage to work, it’ll save your overall energy costs.

Electric water heaters are more energy-efficient than gas units. However, because gas costs less than electricity, the 2 break even cost-wise.

To ensure that you get an energy-efficient water heater for your home, look for the energy star logo. If the model has the logo, it meets the energy star standards for efficiency.

Frequently Asked Questions

Q1. How Many amps does a Rinnai Water Heater Use?

A Rinnai tankless water heater requires 120 volts AC and less than 3 amps.
The brand provides some of the most cost-effective and efficient tankless water heaters.

Q2. How many amps does it take to run a tankless water heater?

A standard electric tankless water heater requires at least 120 amps to run. The capacity for an average home is 200 amps.
A gas tankless water heater requires only a minimal electrical connection. What you need to look into is the installation requirements of the heater before paying for it.

Q3. How many amps does a tankless water heater use?

The average electric tankless water heater uses at least 120 amps. The average household’s capacity is 200 amps.

Q4. How many amps does a tankless water heater use?

The number of amps a water heater uses depends on the fuel it uses. The amperage for electric heaters differs from a unit that runs on gas.
On average, an electric water heater uses 120 amps, and the capacity of an average home is 200 amps.
Gas models need a minimal electrical connection.


Different electric tankless water heaters have different amperage requirements. That’s why you need to check a model’s amperage specs before paying for it.

Gas tankless water heaters require a minimal electrical connection, and thus amperage requirements are not fundamental. However, you need to check on the venting options since you don’t want to end up with a model that’s too complex for you to install.

When you buy something through our affiliate links, we earn a commission without you having to pay extra.