Hot Water Recirculation Heat Loss Calculator
Estimate hot-water recirculation loop heat loss and pump energy from pipe length, temperature difference, editable reference heat-loss rate, runtime and electricity price.
Default project preview
2,765 kWh/year
Temperature difference
50 °F
Pipe thermal energy
2,619 kWh/year
Pump electrical energy
146 kWh/year
Daily operating time
16 h/day
Calculator
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Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Total supply and return loop length
Enter this project assumption in ft. The current imperial default is 180 ft.
Average recirculating water temperature
Enter this project assumption in °F. The current imperial default is 120 °F.
Average surrounding temperature
Enter this project assumption in °F. The current imperial default is 70 °F.
Heat loss per length at reference ΔT
Enter this project assumption in Btu/h per 100 ft. The current imperial default is 850 Btu/h per 100 ft.
Reference temperature difference
Enter this project assumption in °F. The current imperial default is 50 °F.
Recirculation runtime
Enter this project assumption in hours/day. The current imperial default is 16 hours/day. Minimum: 0. Maximum: 24.
Circulation pump electrical input
Enter this project assumption in W. The current imperial default is 25 W. Minimum: 0.
Electricity rate
Enter this project assumption in per kWh. The current imperial default is 0.18 per kWh. Minimum: 0.
How to read the outputs
Temperature difference
water minus surrounding temperature. Default preview: 50 °F.
Pipe thermal energy
during entered runtime. Default preview: 2,619 kWh/year.
Pump electrical energy
25 W pump. Default preview: 146 kWh/year.
Daily operating time
5,840 hours/year. Default preview: 16 h/day.
Reference heat-loss rate
at 50° reference difference. Default preview: 850 Btu/h per 100 ft.
Estimated annual cost
thermal replacement energy plus pump electricity. Default preview: $497.64.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Heat loss is scaled from the entered reference rate by loop length and actual temperature difference. Annual thermal loss and pump electricity use the entered daily runtime.
Related tools
Continue planning the project
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Hot Water Recirculation Heat Loss Calculator questions
Where should the reference heat-loss rate come from?+
Use pipe-insulation manufacturer data, measured performance or a project calculation for the actual pipe size and insulation.
Why include pump energy separately?+
The circulation pump uses electricity in addition to the energy needed to replace heat lost from the loop.
Does continuous recirculation always save energy?+
No. It improves delivery time and can save waiting water, but long runtimes may increase pipe heat loss. Demand controls can reduce that penalty.