Venting a Central Vacuum System Outdoors
We recommend that you vent your central vacuum outdoors. To do so, run PVC pipe from the vacuum exhaust to the exterior of the house, and add a exhaust vent to the outside of the house. Venting to the outside is more effective than having a HEPA filter on your vacuum. A HEPA filter is 99.97% effective, where a central vacuum vented outside is 100% effective, all the particles that come through the exhaust go directly outdoors rather than indoors.