Scroll to top

A Complete Guide to Thermal Insulation for HVAC Ducts – Materials, Thickness & Calculations

  • Home
  • Blog
  • A Complete Guide to Thermal Insulation for HVAC Ducts – Materials, Thickness & Calculations
2 min read Insulations

What is Insulation material?

An insulation material is any substance that slows the transfer of heat by conduction, convection, or radiation, acting as a barrier to reduce heat loss or gain and maintaining stable indoor temperatures.

 

Why Duct Thermal Insulation is required?

How to calculate Insulation material Thickness for A/C ducts?

Step 1 :  SELECT THE INSULATION MATERIAL TYPE

Nitrile Butadiene Rubber Insulation material

Step 2:  FIND OUT THE THERMAL CONDUCTIVITY  & EXTERNAL SURFACE COEFFICIENT OF THE INSULATION

 MATERIAL

For Nitrile rubber insulation

Thermal Conductivity  (k)              :  0.038 W/m 0C

External Surface coefficient (h)  : 9 W/m2 0C

Step 3:  COLLECT AMBIENT CONDITION OF THE PARTICULAR CITY

For Example Chennai ambient condition for Monsoon season

Ambient Dry Bulb Temperature (Tamb)                   :  28.3 0C

Surrounding air Wet Bulb Temperature (Twb)      :  26.00 0C

Surrounding air Dew Point Temperature (Tdp)     :  22.28 0C

Surrounding air Relative Humidity (RH)                :  80%

Step 4:  CHECK THE SUPPLY AIR TEMPERATURE TRAVELLED INSIDE THE DUCT

Air Temperature inside the duct (Tcold)     :  12 0C

How to calculate Insulation material Thickness for A/C ducts  ?

The duct thermal insulation thickness is calculated to prevent condensation using the following equation (applicable where ducts are installed inside the building)

X = (k/h) * [(Tdp – Tcold) / (Tamb – Tdp)]

X = (k/h) * [(Tdp – Tcold) / (Tamb – Tdp)]

= (0.038/9) * [ ( 22.28 – 12) / ( 28.30 – 22.28)]

= 0.0042 * [ (10.28) / (6.02) ]

= 0.00717 m

X   = 7.17 mm  (Required insulation thickness)

Selected Insulation thickness is 9mm

(Standard Insulation thickness available in the market)

Get the latest updates on HVAC trends, products, and success stories - delivered to your inbox.