Leaky ducts waste energy
ENERGY STAR estimates that in a typical house about 20–30% of the air moving through the duct system is lost to leaks, holes and poorly connected ducts. Ducts in attics and crawl spaces lose the most. Professional sealing with mastic or aerosol sealant, plus insulation, typically costs $500–$2,500.
Filtration
| Filter | Captures | Notes |
|---|---|---|
| MERV 1–4 | Large dust, lint | Protects equipment only |
| MERV 8 | Pollen, dust mites, mold spores | Good default for most homes |
| MERV 11–13 | Fine particles, pet dander, some smoke and bacteria | Check that your system can handle the airflow restriction |
| HEPA | 99.97% of particles at 0.3 microns | Usually needs a dedicated bypass or portable unit |
Humidity
Aim for roughly 30–50% relative humidity indoors. Whole-home dehumidifiers ($1,500–$3,500 installed) help in humid climates. Steam or bypass humidifiers ($400–$1,500) help in dry winters.
Duct cleaning: when is it worth it?
The EPA notes that duct cleaning hasn't been shown to prevent health problems, but recommends it when there's visible mold, vermin or excessive dust and debris. Avoid "$99 whole-house" duct cleaning offers. They're often bait.
Frequently asked questions
What MERV filter should I use?
MERV 8 suits most homes. MERV 11–13 helps with allergies if your system can handle the extra airflow restriction. Ask a technician to check static pressure.
