When condensation forms within the tube of a sun tunnel, it is most likely due to an issue across the length of the tunnel itself.

The sun tunnel does not produce water, therefore the moisture must be originating outside of the tunnel, and entering through small gaps across the tunnel itself. This saturated air then gets trapped within the tunnel, and when the conditions are right, it will form condensation. This will most likely be visible as droplets or sometimes pools of water on the internal diffuser pane.

To resolve this, we would advise you to check the length of the tunnel itself, ensuring there is no gaps or breaks in the tunnel itself, or the taping which is required during installation. If there are any gaps, please use thick silver tape to seal this where possible and monitor the situation further.

We would also advise you to check the connection between the sun tunnel and any insulation which has been wrapped around the tunnel. This is also part of the installation process, so if this has not been done, or has been damaged, we would advise to repair this by replacing with new tape.

If the tunnel section is badly damaged, and needs replacing, please contact VELUX Support by clicking here. You may need to remove the diffuser pane of your sun tunnel to allow any excess condensation to displace, please find information for this by clicking here.

What should I do when I have condensation in my sun tunnel?