How To Choose The Right Tankless Water Heater | San Antonio, TX

How To Choose The Right Tankless Water Heater | San Antonio, TX

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If you have never had a tankless water heater before, the idea of installing one may be intimidating. However, if you want to make your home more energy-efficient and enjoy constant access to hot water, then it may not be a bad idea to look at your options. Upfront, tankless water heaters tend to cost more, but they have a much longer lifespan if properly maintained and utilize much less water which means reduced energy bills. Over time, the upfront investment will be worth it.

If this is your first time looking at tankless water heaters, you may feel lost looking at your options. It is always a good idea to consult with a plumber to make sure the model you choose is the right fit for your home, but there are a few things that can help you with your decision. Here are a few things to consider when you start looking at models and pricing the actual expense associated with these water heaters.

What Size Tankless Heater Is Right for My House?

Choosing the right size is the most important part of buying water heaters in San Antonio, TX. If you buy a model that is too small of your home then you will probably find that you are running out of hot water because the heater cannot keep up with demand. On the flip side of things, if you purchase a unit that is much larger than what you need you will end up spending more on heating your water. Therefore, in the end, you won’t truly get the benefit of energy efficiency out of your purchase.

With this in mind, there is not a lot of leeway when it comes to sizing tankless water heaters. You need to carefully think about the size of your home, your daily water usage habits, and how many people live in your home. This is a good base, but not the final factors that influence sizing. A plumber will take a look at the flow rate and temperature rise. Here is a closer look at both so that you can make an educated choice.

Temperature Rise- The Change of Water Temperature in the Water Heater

The necessary temperature rise determines how hard water heaters have to work and how powerful it will need to be. The temperature rise is the difference between the temperature of the water when it goes into your water heater and the expected temperature it will be when it comes out. Of course, changing seasons will affect the temperature of the water as it enters the pipes, but in general, every area still has an average groundwater temperature. You can use this average to determine how much work your water heater actually has to do.

Locals experience high temperatures year-round, which means that tankless water heaters, in general, will not be working as hard as a system that is located in the northeast corner of the US. Around the San Antonio area groundwater averages around 67 degrees. That means your starting temperature will be about 67 give or take. Your local plumber can give you a closer estimate. Most homeowners want hot water to be about 102 degrees for bathing and 120 degrees for the washing machine and dishwasher. If your water starts at 67 then you need to heat it an additional 35 to 53 degrees. This number is the temperature rise that you need to search for when browsing through water heaters.

Flow Rate

Now that you know the amount of heat you need, you need to determine how much hot water you need. The flow rate represents how much water can be produced by tankless water heaters every minute. The exact measurement is gallons per minute. Since water is produced on demand with a tankless system, you can’t rely on stored water to be divided throughout the home. Instead, you can only use as much water as is available. Regardless of what flow rate you choose, installing tankless water heaters will likely mean that you can only do one or two hot water activities at a time such as taking a shower and running the dishwasher or running the washing machine and bath.

In general, a sink faucet requires 1-1.6gpm while a showerhead requires 2.5gpm. A tub faucet requires 4gpm and a dishwasher takes 1.5gpm while the washing machine takes 2gpm. Now, think about how often you use each of these plumbing fixtures on a regular basis. If two people use the bathroom in the morning you will need at least 5gpm to support them, or if you tend to run the dishwasher and washing machine in the evening you will need at least 3.5gpm. Keep these figures in mind when you start pricing tankless water heaters and attempting to pick the right model for your home.

Considering Both Features Together

While you need to look at both of these numbers, it is important to know that these factors can influence each other. Temperature rise can impact how many gallons per water are produced because it determines how hard the system has to work. The same water heater that can only flow at 5gpm in the north because of a 60 degree temperature rise may be able to deliver 8gpm in the south because of a much lower 30 degree temperature rise.


It can be confusing trying to sort through this information on your own, which is why it is helpful to have a professional plumber to guide you through the math. bluefrog Plumbing + Drain of San Antonio, TX is happy to come out to your home to help you assess your hot water requirements. We can help you choose and then install a tankless water heater that will meet your family’s hot water demands. Give us a call and we will help you get the most out of your investment.

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