I bought a 440 CFM inline exhaust fan because I was originally planning on growing in a bigger area than I ended up in. I now have that fan in a 4x4x80 tent and I think it’s too powerful in a passive intake setting. It sucks away all the humidity that I build up in the room for my seedlings (even on the lowest setting).
What should I do? Exchange for a fan of correct CFM? Could I add an inlet fan of similar power instead? I’d also like to be able to pump cool air from an AC into the tent on a controller. When this kicks on with a new fan setup, will I again experience my humidity getting blown away?
As @dbrn32 says with your seedlings.
As for the fan - definitely too powerful. You would be better starting with around 300 cfm/ 1"wg pressure ability at high speed (centrifugal or mix flow), and slow from there when required. It will be easier to manage with an inlet fan at around 150 cfm flow (axial). Be careful of the filter you have. It has a 4" inlet, will likely require a reducer off your fan - and it will load your fan up. Keep your duct runs and bends smooth and keep the flexible duct stretched.
it would be bad if the fan was over cranked but the undercranking capability is what they have in hotels (where its hot) and they are all on a in-line dimmer switch, contact the manufactures or ask your friendly electrician .
I was a Lighting Gaffer for over 30 years and many a fan was hooked up to an in-line dimmer.
