Our basement is partially finished, approximately 50/50 in terms of square footage. It was used as a mother-in-law suite at some point by a previous owner.
The finished rooms are air conditioned/heated from our single central HVAC system. We also run a portable, 70 pint or so, dehumidifier in the "K" room
Our problem is that it is very humid down there and the air is pretty musty smelling. Humidity is typically 50% or greater in the summer months. In the winter, it drops to low 40s. We have white mold growing on a few items down there.
The current HVAC and dehumdifier aren't cutting it. We called in a basement/moisture company and they recommended a dedicated whole-house dehumidifier, ducted to just the basement. It was a $5k quote.
I am hands on, so I'd like to tackle this myself. I can save quite a bit of money, and it seems that the installation will be pretty simple, given that I have easy access to all the rooms.
I do not plan on integrating it with the existing HVAC ductwork. That will increase complexity and we may have an HVAC overhaul in the future.
I have attached a basic sketch of the basement and rooms. Finished rooms are BR, K and LR. There is a bath attached to the BR (not ducted, but there is a "window" to the unfinished portion of the basement.) I am planning on installing the unit in the unfinished space, near the existing HVAC. I have several ways to get the condensation out of the house from that location - pump outside, pump into washer stand pipe, pump into sewage pump.
I want to duct work the "K" room and another in the "BR," but I am not sure how to include the unfinished portion of the basement. We use the left most portion of the unfinished space for storage, so I would love to control the moisture level in that area.
Should my goal be to create a circular flow of air? One return in, say the K, and a supply in BR? Should the unfinished storage area have a supply or return?