A fresh air flex duct pulled away from the exterior wall outlet, held by a loose zip tie, plus an unrated filter screen with gaps that let air bypass it.
We are homeowners, not HVAC professionals. This page documents what we observed with the fresh air intake system.
The Issue
| Item | Observation |
|---|---|
| Fresh air flex duct | Runs from an exterior hood into the main return plenum |
| Filter screen | Missing during home inspection. CBH added a light-blue screen afterward. The screen had no label, no MERV rating, and no maintenance instructions. Gaps around edges allowed air to bypass the filter. |
| Duct connection | The flex duct pulled away from the exterior wall outlet. The plastic collar tore through the screw holes. A zip tie was loosely holding the duct near the wall. |
Detached duct in the attic
Evidence
Original Filter (no rating)
MERV-1 Filter after 2 months (Summer 2024, fire season)
Air quality monitor readings:
| Scenario | Before filter replacement | With MERV-1 pad |
|---|---|---|
| Wildfire smoke events | Indoor readings reached “Unhealthy” within an hour | Readings reached “Moderate” |
| High-pollen days | Spikes observed on monitor | Lower spikes observed |