Registered: 1352981942 Posts: 2,286
Reply with quote #21
The smallest orifice in the path of the air will be a so-called bottleneck, which will restrict airflow. You will want to eliminate as many bottlenecks as possible. So if the fan has 20CM(roughly 8") diameter openings, try and keep the ducting the same size as well. While the "breeze" might not feel like it is moving much air, you should focus on the actual volume of air being moved. Your fan will move a percentage of the rated capacity. So the 550CFM)935m3 fan might only move 70% of the rated capacity. This is yet another reason to choose a higher capacity fan than you think you will need. The output can always be reduced if needed.
When you are ready to start your build you will want to start a new topic in the Sunspace forum. Greg in MN
Registered: 1458141100 Posts: 27
Reply with quote #22
If you`re buying a brand new fan try to find one that offers detailed specifications. A vents vk 200 will do about 450cfm at 0.2" wc (50Pa). Not overly cheap at around 100 euro but with the 5yr warranty its 20 euro a year. I have the vk 250 and vks 315 and cant fault either of them.
http://www.ventilation-system.com/item/vk-200/#diagrams us version: https://v-fans.us/vents-vk-200.html