Topic: All Weather Inc. Motor Aspirated Radiation Shield

[JCA433]

The volume of the air moving through sensor chamber is more important.   A small diameter tube should have less mass than a larger size tube reducing the need for increased Fan CFM 

[CW7491]

That certainly seems to the conclusion from what I saw. 43CFM fan gives better results in a 3” tube vs a 2” tube even though it acts like a small vacuum with a 2” tube

[JCA433]

CW, it is easier to determine what size FAN CFM required though observation and comparing to your reference than calculations.  That math is fairly complex.  It is a lot of work, but it pays off eventually.