What is Flow Rate, and Why is it Important to Tankless Owners?

At Tankless Guide we have received many e-mails asking about water flow rate. It is very important to understand this term. Flow rate can be used to describe several different things. Lets take a look at what those differences are and how they will affect your tankless purchase.

The Federal Energy Policy Act of 1992 required all faucet / shower fixtures made the USA to have a flow rate of no more than 2.2 GPM at 60 PSI. All fixtures made prior to 1992 are Grand Fathered in. So if you have older faucets they may have a much higher flow rate.

The Flow From The Tap

The flow rate at the tap generally refers to the number of gallons of water you get per minute. To determine this you could buy a fancy device to determine the flow or you could take a bucket mark a line at 2 gallons  or 4 gallons and turn on the tap and using a kitchen timer determine how long it takes to hit that mark.

So if it takes 2 minutes to hit the 4 gallon mark you are getting 2 gallons per minute out of the tap. This will give you an idea of how much water you are getting or using per minute.

Tankless Heater Flow Rate

The term flow rate for a tankless water heater is slightly different. You have to add in temperature rise required to meet your target water temperature. Once you have determined your ground water temperature and the temp you want at the tap you have determined your rise needed. Once you have determined the rise you then can determine flow rate. Which is how many gallons can rise in temperature to meet your tap requirement per minute. Using the Noritz tankless heater as an example. Their company has produced a great reference chart that shows exactly  which size model is best for you.

In Conclusion
If you use an old style tank water heater the term flow refers to the number of gallons of hot water coming out of the tap. if you use a tankless water heater flow rate refers to how many gallons the unit can heat in a minute.

Remember: All tankless water heaters should be installed by a licensed professional. If you decide to DIY make sure to read your warranty as well as your local codes first.Don’t know where to start get free quotes from your area.

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