What Size Tankless Water Heater Do I Need

Ever had your shower turn cold halfway through? A tankless water heater that’s sized right for your home keeps that from happening. Cassell Brothers helps homeowners in Columbia, Irmo, and throughout the Midlands pick the right unit and get it installed the right way. 

Our plumbers know South Carolina homes and how the climate affects your water use. We take real measurements, ask the right questions, and make sure your tankless system keeps up with how your family actually lives. 

Why Choosing the Right Size Tankless Water Heater Matters 

A tankless water heater doesn’t keep a reserve like a traditional tank. It heats water as you use it, minute by minute. That means your system has to keep up with the flow of water running through it. If the unit is undersized, you’ll feel the temperature drop when someone starts the washing machine while you’re in the shower. If it’s oversized, you’ll spend extra on equipment and energy you don’t need. 

When the size is right, your water heater runs efficiently and lasts for years. In the Midlands, smaller households usually need around four to six gallons per minute of hot water during peak times. Medium-sized families might need six to nine. Bigger homes with several bathrooms can use ten gallons a minute or more when everything is running. 

How to Determine the Right Size Tankless Water Heater for Your Home 

Finding the right fit isn’t complicated, but it does take a few careful steps. 

Step 1: Identify Your Peak Hot Water Demand 

Think about the busiest time of day in your home. Maybe it’s mornings before work and school, or evenings when showers, laundry, and dishes all overlap. Count how many fixtures use hot water during that stretch. That gives you your household’s peak demand. 

Step 2: Estimate Your Flow Rate 

Each fixture uses a set amount of hot water. A standard shower averages two gallons per minute. Kitchen faucets and dishwashers use roughly one and a half to two. Add them together. If two showers and a washing machine often run at once, you’ll need a system that can produce about seven to eight gallons per minute without slowing down. 

Step 3: Adjust for Columbia’s Water Temperature 

Here in Columbia and Irmo, the incoming water temperature is warmer than in many parts of the country, hovering around sixty-five degrees. That means your system doesn’t have to work as hard to heat the water, and in most homes a slightly smaller unit still performs beautifully. 

Average Tankless Water Heater Sizes for Common Households 

Every home is different, but experience gives us a good starting point. 
A one- or two-bathroom home typically runs well on a system that provides about four to six gallons per minute. Families with three or four bathrooms usually need six to nine. Larger properties, or homes that use several fixtures at once, might need nine to twelve gallons per minute or even two units working together. Cassell Brothers helps you sort through those numbers and find the size that fits your home, not someone else’s. 

Gas vs. Electric Tankless Water Heaters: Which Is Right for You? 

Both options deliver hot water efficiently. Gas units heat faster and handle higher demand, which works well for big households or frequent simultaneous use. Electric systems are compact, simple to install, and great for smaller homes or supplemental setups. 

If you’re not sure which direction to go, Cassell Brothers can walk you through it. We’ll look at your home’s plumbing, available utilities, and energy costs, then help you choose what makes sense for your space. 

Professional Sizing and Installation from Cassell Brothers 

Installing a tankless water heater takes real know-how and attention to how your home uses hot water day to day. The Cassell Brothers team looks at your actual usage, recommends the right model, and installs it carefully so it performs the way it should. 

We handle the whole process, taking out the old system, upgrading venting or gas lines if needed, setting temperatures, checking flow rates, and cleaning up when we’re done. Once it’s running, we’ll walk you through how it works and what kind of maintenance keeps it efficient. 

Cassell Brothers has been serving the Midlands for decades, and our reputation comes from more than skill. It’s built on honesty, respect, and doing the job right the first time. 

Schedule a Tankless Water Heater Consultation in Columbia, SC 

If you’re ready to upgrade your water heater, start with a consultation from Cassell Brothers. We’ll evaluate your home, calculate flow rate, and recommend the system that fits both your comfort and your budget. 

Call today to schedule your appointment or reach out online to learn more. Our team will help you choose the perfect tankless water heater for your home in Columbia or Irmo and install it with the care and attention you deserve. 

Call on Cassell Brothers for comfort, the name you can trust in the Midlands.