Domestic hot water recirculation (DHWR) systems can provide the convenience of instant hot water and save thousands of gallons of water per year. But did you know that an improperly sized circulator can be a big inconvenience, and potentially cost you thousands of dollars?

An undersized circulator might not provide enough flow to keep the water in the lines hot, resulting in a hot water recirculation system that doesn't do what it's supposed to - and an unhappy customer. An oversized circulator will result in higher initial cost for the pump, greater energy use, and possible premature pipe failures due to wear and tear from too much flow, resulting in costly damages from a leaking system.

Taking the time to properly size the circulator upfront can help avoid potentially massive headaches down the road. But knowing the formulas and doing the math to correctly size a circulator for a domestic hot water recirculation system can be time consuming and slow down a job.

With the Taco Comfort Solutions DHWR SizeRight Circulator Sizing Tool, you can now properly size a circulator in a fraction of the time it would take to do it manually.

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Is there an existing or will there be a DHW re-circulation line installed?
Yes No

Piping Calculations:
Supply Line(s)
Size of Pipe
Total Lineal Feet

Return Line(s)
Size of Pipe
Total Lineal Feet
Feet of Head
Circ Efficiency Type:
Connection Type:

Subtotal Volume: 0
Subtotal Pressure Drop:
0 Feet of Head

Valves & Fitting:


Yes No
Feet of Head Total:
Disclaimer: This simplified DHWR App (V 1.0) uses many assumptions based on typical domestic hot water installations. It uses an MVL (maximum velocity limitation) on the return lines of 2 feet per second. In addition, this App compensates for the additional pressure drop of the valves and fittings in a system by using a multiplier of 1.4 to 1.6 depending whether the fittings are installed over the pipe or inserted into the pipe. We also make the assumption that the MVL flow will be greater than the heat-losses of the supply piping portion. We also assume that the piping will be covered with suitable insulation. Depending on the particular system, these assumptions and multipliers can lead to over or under sizing of the circulator in the system. The user assumes all liability for the outcome and functionality of their DHWR system.