Copper Tubes - Heat Losses

Heat loss from uninsulated copper tubes vs. temperature differences between tube and air.

Nominal Bore (mm)	Nominal Bore (inches)	22°C ΔT (W/m)	38°C ΔT (W/m)	55°C ΔT (W/m)	40°F ΔT (Btu/hr ft)	68°F ΔT (Btu/hr ft)	99°F ΔT (Btu/hr ft)
15	1/2	21	32	45	22	34	47
22	3/4	28	43	60	29	45	53
28	1	34	53	76	36	56	79
35	1 1/4	41	64	89	43	67	93
42	1 1/2	47	74	104	49	77	108
54	2	59	93	131	62	97	136
67	2 1/2	71	111	156	74	116	162
76	3	83	129	181	87	135	189
108	4	107	165	232	111	172	241

Notes

1 W = 3.4 Btu/hr
1 ft (foot) = 0.3048 m

Reference

Heat loss values from uninsulated copper pipes vary based on the nominal bore diameter and the temperature difference between the tube and the surrounding air. Use the table above to determine heat losses for your specific application.