Water-heating load calculator

Convert gallons to pounds before applying water specific heat and temperature rise.

Units

q_{\text{water}} = \dot{V} \times 8.345 \times c_{p} \times \left(T_{\text{out}} - T_{\text{in}}\right)

Calculator

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

Given

q_{\text{water}} = 480 \times 8.345 \times 1 \times \left(145 - 60\right) = 340{,}476

Symbol	Meaning	Unit
$q_{\text{water}}$	required water-heating rate	Btu/h
$\dot{V}$	water volume flow	gal/h
$c_{p}$	water specific heat, approximately 1	Btu/(lb·°F)
$T_{\text{out}}$	heated-water temperature	°F
$T_{\text{in}}$	inlet-water temperature	°F

Symbol	Meaning	Unit
$q_{\text{water}}$	required water-heating rate	kW
$\dot{V}$	water volume flow	L/h
$c_{p}$	water specific heat, approximately 1	kJ/(kg·K)
$T_{\text{out}}$	heated-water temperature	°C
$T_{\text{in}}$	inlet-water temperature	°C

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