Pipe Insulation Heat Loss Calculator

Inputs

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Actual outside diameter of the pipe or tube before insulation.
in
Radial insulation thickness. Zero returns the bare-pipe film-loss case.
in
Straight-equivalent pipe length used for total heat loss and annual energy.
ft
Absolute pipe-to-ambient temperature difference. Use the magnitude for hot or chilled service.
°F
Thermal conductivity of the insulation at the mean operating temperature.
Btu-in/h-ft2-F
Combined outside convection/radiation coefficient used after conduction through the insulation.
Btu/h-ft2-F
Annual hours used only for energy and cost estimates.
h/yr
Rough energy value for annual cost. Adjust for boiler efficiency or equipment COP outside this calculator.
$/kWh

Results

Default result
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Insulated heat loss (q)
1,392 Btu/h
Pass

steady-state conduction through cylindrical insulation plus outside film loss

Also computed

Heat loss per length (q') 13.92 Btu/h-ft

Bare-pipe heat loss (q_bare) 4,850 Btu/h

bare-pipe comparison uses outside film resistance only

Bare loss per length (q'_bare) 48.5 Btu/h-ft

Heat saved (q_saved) Pass 3,459 Btu/h

bare-pipe loss minus insulated loss

Heat saved per length (q'_saved) 34.59 Btu/h-ft

Heat-loss reduction (R) Pass 71.31 %

reduction relative to the simplified bare-pipe film-loss case

Pipe insulation heat-loss previewPipe insulation heat-loss previewCylindrical insulation resistance plus outside film resistancepipeinsulated heat loss1392 Btu/hsaved versus bare pipe3459 Btu/hScreen only. Final insulation thickness, jackets, condensation, personnel protection and energy compliance need project criteria and vendor data.
Method notes 3 notes
  • q' = dT / (ln(r2/r1)/(2*pi*k) + 1/(2*pi*h*r2)); total q = q' * L.
  • Bare-pipe comparison is simplified as outside film loss only; radiation, wind, jacket emissivity, pipe wall, inside film, fittings, supports and moisture are not modeled.
  • For chilled water, condensation control and vapor barriers usually govern before annual energy savings do.

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