When Changing The Filter, Which Way Should The Arrow Point?
The arrow is always pointing the direction of air flow and should always point toward the furnace. This is the air returning from your house carrying dust and other potential allergens. The filter is used to keep these from getting into the furnace and also to clean the air you breathe. Inexpensive filters mainly help to protect the blower from dust, and the more expensive ones can help you control particles that could be harmful for your health.