Ducting Whole Home Dehumidifier – GreenBuildingAdvisor

We’ve recently had closed-cell spray foam installed on the open crawl space floor and open-cell to encapsulate our attic. Our house is a 2B/2B, just over 1000sqft, located in south Louisiana. 

I’m looking to install an Aprilaire E080 dehumidifier in the attic. While we do have ducted HVAC already, i’d prefer to keep it separate so it can run independently. 

My preference would be to have supply ducts to at least the bedroom, office, main bath, and living area but it seems that there’s a lot of technical calculations that go into getting the supply plenum and duct size/length correct.

With individual room ducts seemingly out of the picture,  i’m mulling over running the 10″ supply to a lay in ceiling-mounted supply grille with a 4″ filter and omitting the internal filter in the Aprilaire since my attic access isn’t that great. This would allow me to easily change out the filter as well as reduce any possible issues with high static pressures. 

For supply, i’m considering a 10″x8″8″ metal wye to run flex duct supplies to the living area and main bedroom. I’ve attached a rough drawing of the layout. 

The unit is located in the attic, close to my HVAC system so i can pipe the condensate to the existing HVAC drain. I will install a cut-off float in the drain pipe as well as a drain pan with alarm under the Aprilaire unit. 

Is this a decent plan or any suggestions on tips on how i can improve the layout? 

Layout – Couldn’t seem to attach it: https://i.imgur.com/12j73Fx.png