What is the maximum length of ducting for a cooker hood? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[earnshaw]

I am installing a cooker hood and want to duct out the air to an outside wall, but its around 15ft away. Is there a maximum amount you can have your ducting before it ceases working as it should or you have to electrically pump it out with a fan or something?