Dehumidification and Minisplits
I’m in Austin TX. We have significant humidity, including in “shoulder” seasons where cooling is not really needed but dehumidification is. Probably the worst times are when the day is hot and humid, but the night is cold, condensation on windows is a major problem all over the city. No one likes running the AC to super chill just to dehumidify.
So the smart recommendation is a dedicated dehumidifier, like the Ultra-Aire series. Ok, costs a bit more than AC only but everyone says they are great.
My question is about combining dehumidification with getting ducting out of the attic. Seems a contradiction between using mini-split systems (ductless or very short run ducted), since now one doesn’t have a ducting system into which to place the dehumidifier.
Yes, best solution would be to encapsulate the attic. Then one could pick and choose, perhaps running a small ducting system just for the dehumidifier. In our place, though, many years of additions has left a very cut up attic, mitigating against encapsulation from below (spray foam). A chainsaw renovation might work, but that would require adding siding on the whole house (currently stucco on block), as well as the whole re-roof, estimates for that range up above $100k (Austin, man, stop moving here, people :).
So, boiling this down. Are there any knowledge or resources about:
– required ducting extent and design for dehumidification only (not heating/cooling air distribution). Does diffusion of moisture work differently than diffusion of temperature sufficiently to mean that single point (or two points) of dehumidification could be sufficient?
– Would there ever be a reason to choose a central ducted AC/Heating system, with the ducts in a hot attic, just to include dedicated central dehumidification?
– I’m also interested in knowing which ducted mini-splits have great latent capacity? Can “dry-mode” remove sufficient moisture without super chilling a room?
I keep thinking: mini-splits come from Asia (ok, so reached their zenith in Asia), how do people in Asia manage dedicated dehumidification? Then I wonder if they have areas with humid “shoulder seasons” needing high latent capacity but low sensible capacity. Maybe not in Singapore, but surely in Japan, Korea, and China? Quick googling shows some discussion in HK (most english, most north) and has people using portable units in small apartments, not without frustration.
Maybe something more exotic, like desiccant wheels using the heat in the hot attic to recharge?
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