Annual hot-water leak energy calculator

Quantify a continuous hot-water leak using makeup-water temperature and leak duration.

Units

Q_{\text{year}} = \dot{V}_{\text{leak}} \times 8.345 \times c_{p} \times \left(T_{\text{hot}} - T_{\text{makeup}}\right) \times H

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

Q_{\text{year}} = 4.5 \times 8.345 \times 1 \times \left(155 - 65\right) \times 5600 = 18{,}926{,}460

Symbol	Meaning	Unit
$Q_{\text{year}}$	annual useful heat lost in leakage	Btu/year
$\dot{V}_{\text{leak}}$	hot-water leakage rate	gal/h
$c_{p}$	water specific heat	Btu/(lb·°F)
$T_{\text{hot}}$	leaking hot-water temperature	°F
$T_{\text{makeup}}$	replacement-water temperature	°F
$H$	annual leak duration	h/year

Symbol	Meaning	Unit
$Q_{\text{year}}$	annual useful heat lost within leakage	kWh/year
$\dot{V}_{\text{leak}}$	hot-water leakage rate	L/h
$c_{p}$	water specific heat	kJ/(kg·K)
$T_{\text{hot}}$	leaking hot-water temperature	°C
$T_{\text{makeup}}$	replacement-water temperature	°C
$H$	annual leak duration	h/year

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.