Heat Transfer Coefficients in Heat Exchanger Surface Combinations

Average overall heat transmission coefficients for fluid and surface combinations like Water to Air, Water to Water, Air to Air, Steam to Water and more. These coefficients are used to calculate total heat transfer through a wall or heat exchanger construction.

Fluid 1	Surface Material	Fluid 2	U-Value (Btu/ft² hr °F)	U-Value (W/m² K)
Water	Cast Iron	Air or Gas	1.4	7.9
Water	Mild Steel	Air or Gas	2	11.3
Water	Copper	Air or Gas	2.3	13.1
Water	Cast Iron	Water	40-50	230-280
Water	Mild Steel	Water	60-70	340-400
Water	Copper	Water	60-80	340-455
Air	Cast Iron	Air	1	5.7
Air	Mild Steel	Air	1.4	7.9
Steam	Cast Iron	Air	2	11.3
Steam	Mild Steel	Air	2.5	14.2
Steam	Copper	Air	3	17
Steam	Cast Iron	Water	160	910
Steam	Mild Steel	Water	185	1050
Steam	Copper	Water	205	1160
Steam	Stainless Steel	Water	120	680