How do you know what size tankless water heater to buy?

So you have made up your mind to go for a tankless water heater but stuck with what size you should be going for. Don’t worry, we have you covered in our topic.

There are multiple factors that need to be taken into consideration before choosing the right size for your requirements. Remember that you should never try saving money by under sizing your tankless water heater because it will further cause your problems and increase your bills.

First determine on how many devices you would want to run with the hot water from your new tankless water heater. Figure out the total flow rate of these devices and add up their flow rates in gallons per minute. Now make sure the output flow rate of your tankless heater matches the calculated total flow rate.

If any of the device is far away from the heater, it will result in loss of heat by the time water reaches the device through long pipelines. In that case, we suggest going for parallel installation of two water heaters for individual devices.

Figuring out required temperature rise. To determine the required temperature-rise from your heater, subtract the incoming water temperature from the desired output temperature. Now that we have figured out the desired temperature-rise, let’s put it into use.

Let’s consider you are running 2 showers simultaneously; you may need around 6 gallons of hot water per minute from your heater. Ideal shower temperature would be 104-106 degrees. So if your incoming water temperature is 40 degrees, you would need a tankless water heater which produces 60 degrees’ temperature rise and has an output flow rate of 6 gallons per minute.

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