Ventilation in old house that will soon get new heating-cooling system
I am a homeowner interested in ventilation and air quality, and I’m hoping for objective feedback on my situation (the HVAC companies have been helpful, but I’m skeptical of some of the air-quality machines they’ve proposed).
I have a leaky 1920s home (four people, 2,000 sq ft including basement and three bedrooms, 2×6 exterior walls) in the Pacific Northwest on the water (comparatively mild winters and summers, humid), if that information helps.
For heating and cooling, I’m leaning towards a ductless minisplit system, although I might go with a hybrid heat-pump/gas furnace connected to ducts.
There are a few reasons why am I interested in ventilation despite having a leaky house. An IAQ consultant recommended ventilation to deal with accumulation of CO2 that was showing up in his air-quality test of my house. I’ve also gotten feedback from other family members that the air in the house is a little stuffy. And some family members are susceptible to respiratory infections, and I am hoping that more fresh air might help with that. So ventilation seems like a good way to make the air fresher and potentially increase air quality without buying hyped-up, potentially harmful air scrubbers and the like.
So for ventilation, I know one option is an exhaust-only system with a WhisperGreen fan set on 30CFM in each of the two bathrooms (one on main floor, one in basement). But the house doesn’t have an open floor plan. More importantly, I don’t love the idea of creating pressure that would draw even more air through the house’s random cracks (and whatever humidity, mold spores, dust, etc. that would be brought through those openings) or up through the cracks in the house’s foundation/slab (house is located slightly uphill and 1,000 feet away from a former landfill). My preference is to have a bit more control over the source of the supply air, acknowledging that the house is already taking in some outside air through the house’s random cracks.
If I go with a ductless system, I’m considering spot ERV/HRVs, such as Lunos, TwinFresh Comfo, or Panasonic WhisperComfort (according to Panasonic’s recommended zones map, I’m in Zone A and could use this unit throughout the year). Depending on budget, I’m envisioning one each in the bedrooms, one in the basement, and one on the main floor, for five total. I understand an option might be passive air inlets, acknowledging that at a 2000 Vermont study raised questions about such inlets’ effectiveness. For ductless fresh-air supply, I’m seeing Fresh 80, Panasonic FV-GKF32S1, and ASV-90 are options.
If I go with a ducted system, I’m considering spot ERV/HRVs, a whole-house ERV/HRV hooked into the ducted system (I’ve read here that it’s ideal to have an ERV/HRV running air through ducts separate from the heating/cooling system, but that’s not practicable with my old house), or two WhisperGreen exhaust fans paired with an central-fan-integrated supply (with FanCycler, Aprilaire 8120, or other). If I went with the central-fan-integrated supply, I’d probably try to adjust the WhisperGreen fans and AirCycler to get slightly positive pressure (I like the advantages of positive pressure highlighted in the ‘Supply Ventilation’ page on this site).
So I’m hoping that someone here might have feedback (i.e., for the ductless and ducted scenarios, which would ventilation system would work best without being really costly to install or operate?) based on their expertise as an industry professional or based on their experience as a homeowner in similar circumstances.
Thank you for your time.
Notes: I’ve tried to educate myself, including by reading the following pages on this site:
– Designing a Good Ventilation System, https://www.greenbuildingadvisor.com/node/13663
– Fresh air for mini-splits, https://www.greenbuildingadvisor.com/community/forum/mechanicals/103109/fresh-air-mini-splits
– Seeking ductless fresh air supply for balanced ventilation, https://www.greenbuildingadvisor.com/community/forum/mechanicals/14217/seeking-ductless-fresh-air-supply-balanced-ventilation
– Supply Ventilation, https://www.greenbuildingadvisor.com/green-basics/supply-ventilation
– Exhaust-Only Ventilation Systems, https://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/exhaust-only-ventilation-systems
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