800 Whole-House Steam Humidifier

Aprilaire 800 would recommend

Aprilaire 800 is awesome.

Aprilair 800 is the best on the market

It really depends on your house and how well sealed it is. We installed a aprilaire 720m and so far has kept our house at 40-45% consistently. But we have a new build, well sealed home. If you have an older leaky house, it may not perform as well. There’s the 800 steam version, but that will use a considerable amount of electricity.

We install the Aprilaire 600M and 800, so I think you're on the right track. FWIW, we haven't had noise complaints with the 800. The location matters, and it also depends on how noisy the heat pump is when it's running. Is the medical condition just cause sensitivity too humidity? Or is there a bigger indoor air quality component that'll require better ventilation and filtration? And depending on the age of the house, air leakage, and location (climate), I'd be concerned about going above 50% relative humidity in winter. It may or may not be an issue where you live.

And it actually works.

We've had the aprilaire 800 steam humidifier for 12+ years now and really like it. It is expensive to run, but it keeps the house at our desired humidity.

We've had the AprilAire 800 for 12+ years now. I love it from both a performance and a maintenance perspective. Maintenance is super easy--just replace the cartridge every year or two and clean out the drain area (mine fills with minerals from the water).