Dehumidifier

Thinking about my room’s ventilation and air quality again.

Goals:

• Keep humidity low. I have way too many plants that are evaporating so much water that my room is always humid.
• Filter air (e.g. dust, mould spores)
• Keep CO2 low
• Keep room cool-ish in summer

Previously I looked at CR boxes and heat recovery ventilation. Now I’m thinking about some type of air conditioning / dehumidifier:

• Box with filters and AC components
• Window duct connect box to outside through a panel in front of a window
• Room duct connecting the outflow of the box to the other side of the room
• Input valve to select if taking air from outside (window duct) or inside (intake directly on the box)
• Evaporator coil with separate fans always blows air from filters to inside (room duct)
• Condenser coil with separate fans blows from filters to inside in winter (room duct), outside in summer (window duct)
• Bypass channel with separate fans blow air only through filters into room duct

Modes:

• Filter mode:
  • box intake -> filters -> bypass fans -> room duct
• Ventilation mode:
  • window duct -> filters -> bypass fans -> room duct
• Dehumidifier mode:
  • box intake -> filters -> evaporator fans -> room duct
  • box intake -> filters -> condenser fans -> room duct
• AC mode:
  • box intake -> filters -> evaporator fans -> room duct
  • box intake -> filters -> condenser fans -> window duct

Then sensors select mode & fan speeds & compressor power, based on humidity, CO2 level and inside & outside temperature. I would like a variable compressor for more quiet and efficient operation. Not sure ow to set up the valves, maybe include backdraft dampers to prevent crossflow between modes..

Or maybe I should do away with the AC option, and just have a separate dehumidifier & ventilation box. It would need double the filters but no valves. Perhaps I could use a cheap 12L/day dehumidifier as-is, attached with its fan intake to a CR box. If that’s too loud, replace the fan with P14s. Then a separate ventilation box with its own filters that takes in outdoor air. Or I guess I could house the filters and fans in the same box, but the air flows would be separate.
Edit: dehumidifiers typically push warm air out the back, not the front, so directly attaching to a CR box is slightly harder than I thought especially if I want to keep the original controls accessible. So I’ve swapped my link for one that takes air in from the back.

I really should think about minimum viable product and optimise for getting it done instead of trying to design the perfect solution and never finishing it.

To be continued..