5 Key Factors to Consider When Choosing a Tankless Water Heater

If you're tired of running out of hot water or dealing with bulky storage tanks, switching to a tankless water heater is a smart move. But with so many options—like electric tankless water heaters, natural gas tankless water heaters, and propane water heaters—how do you know which one is right for your home?

Here are five key factors to consider when choosing the best tankless hot water solution for your needs.

1. Fuel Type: Electric vs. Natural Gas vs. Propane

The first step is choosing the right fuel type:

• Electric tankless water heaters are energy-efficient, compact, and ideal for homes with limited space. They're perfect for both whole house and point of use applications.

• Natural gas tankless water heaters offer a higher flow rate and heat water quickly, making them ideal for larger households with higher hot water demands.

• Propane water heater tankless units are similar to natural gas models but are ideal for off-grid or rural homes where natural gas isn't available.

👉 Pro Tip: If your home is already equipped with a gas line, a tankless natural gas water heater can be a powerful and cost-effective solution. For homes without gas, an electric tankless hot water heater is typically easier to install.

2. Flow Rate (GPM)

Flow rate, measured in gallons per minute (GPM), tells you how much hot water a tankless system can deliver at once.

Here are typical flow rates by fixture:

• Shower: 2.0–2.5 GPM

• Kitchen faucet: 1.5–2.0 GPM

• Washing machine: 2.0 GPM

If you need hot water for multiple fixtures running at the same time, a whole house tankless water heater with a high GPM rating is essential. For individual fixtures, like a bathroom sink or wet bar, a point of use tankless water heater may be all you need.

3. Sizing and Usage Needs

Not all households require the same size water heater. Ask yourself:

• How many bathrooms do you have?

• Do you often use hot water in the kitchen and laundry at the same time?

For larger families or homes with two or more bathrooms, you’ll need a higher-capacity system—like an 18kW–27kW electric tankless water heater or a natural gas tankless water heater with 6–10 GPM flow rate.

For small homes, vacation properties, or single-application needs, a compact point of use tankless water heater is both affordable and efficient.

4. Energy Efficiency and Operating Costs

One of the biggest reasons homeowners go tankless is for energy savings. Traditional water heaters continuously heat a storage tank, wasting energy throughout the day.

Tankless systems only heat water when you need it:

• Electric tankless hot water heaters are highly efficient, especially for homes with moderate water use.

• Natural gas tankless water heaters heat water faster and are more cost-effective for high-demand households.

• Propane models can be a smart alternative for rural or off-grid homes.

Look for models with an ENERGY STAR® rating to ensure maximum efficiency and long-term savings.

5. Installation and Maintenance Requirements

Installation difficulty and cost vary based on the fuel type:

• Electric tankless water heaters are often easier and more affordable to install, especially if you’re upgrading from an older electric unit.

• Natural gas tankless water heaters require proper venting and gas line capacity, which may involve additional installation work.

• Propane units also need proper ventilation and fuel tank placement.

Maintenance, like descaling and flushing the system annually, is key—especially in areas with hard water. Choosing a unit that's easy to maintain can extend its lifespan and ensure optimal performance.

Final Thoughts

Whether you need a whole house tankless water heater or a compact point of use tankless water heater, the right model depends on your home’s layout, usage patterns, and fuel availability.

At ThermoMate, we offer a full line of electric tankless water heaters and can help you determine if an electric, propane, or natural gas tankless water heater is the right fit for your home.

Ready to upgrade your hot water system?
Browse our best-selling models now and experience the comfort of endless, energy-efficient hot water—delivered on demand.