Applications

Thermal Insulated Ducts

Ventilation systems require thermal insulation in order to restrict and control heat loss. For financial and environmental reasons, it is important you reduce unnecessary heat loss in ducts that transport warm air. Ventilation ducts transport either warm or cold air. This, together with the temperature and moisture content of the surrounding air and in the duct, will influence your choice of insulation solution.

Maintain the temperature and heat loss of the air at the specified level when transporting warm air through long ventilation ducts. It is important you keep both criteria at desired level to minimise energy loss.

Ducts that transport cool air also need a good thermal insulation solution. The insulation maintains the lower temperature inside the duct by insulating it from the warmer ambient air temperature. If the cool air in the duct is heated by the surrounding air, the HVAC system functions less effectively and you will need more energy to maintain the duct's correct temperature. If the ducts are properly insulated, the whole ventilation system will work as designed and you need less equipment calibration.

Condensation

Huge problems occur when condensation builds up on the outside of ducts containing material with a lower temperature than the ambient air temperature. With high humidity, the air can easily condense on the outer surface of ducts. When this happens, water starts to drip and causes damage, such as discoloration to ceilings and floors. Over time, water can cause damage to the ducts and reduce their service life. Condensation also occurs inside the duct if the situation is reversed.

Prevent condensation easily by using the correct insulation solution. Apply insulation of the correct thickness to keep the insulation surface temperature higher than the ambient air temperature. Also use an effective water vapour barrier to prevent moisture permeating the insulation.

In the table below you can see when condensation insulation is required.

Duct	Air in the duct	Location of the duct	Why insulate?	Which solution?
Outdoor air duct, Air-condition, etc.	Cold air	In heated, warm space (higher temp than in the duct)	Condensation on outer surface	Thermal insulation + vapour barrier, taping
Heated incoming air, Outgoing air, etc.	Warm air	In unheated, cold space	Condensation on inner surface	Thermal insulation
Heated incoming air, Outgoing air, etc.	Warm air	In heated, warm space	Thermal insulation to reduce energy loss	Thermal insulation

Calculate the correct thickness of the insulation easily by using Paroc’s calculation program PAROC Calculus. If you are required to insulate for thermal purposes and for fire protection, always place the fire insulation closest to the duct and the thermal insulation and vapour barrier on top of the fire insulation. For more information regarding fire protection of ducts, please contact your local Paroc representative.