The sofa fitted between the window and the doorway with room for a little table. I sent a photograph to my sister. She asked whether the white grille behind it was supposed to remain visible.
I had carefully kept the floor heating register clear. The larger wall grille had become part of the background, like a skirting board. Moving the sofa back out revealed how completely I had covered it.
Air also has to leave the room
Source: Carrier: furnace troubleshooting
A forced-air system supplies conditioned air and draws air back through returns. Carrier's troubleshooting guidance calls for keeping both supply and return openings unobstructed. Blocking a return can restrict the system's airflow; it is not simply a decorative opening that can be hidden.
I moved the sofa so the grille had a clear air path and could be cleaned. I didn't use a universal furniture-distance rule from a photograph. The grille arrangement and system requirements deserved their own space.
The new layout put the little table on the other side. That was mildly inconvenient, but less inconvenient than arranging service without mentioning the largest change we had made to the room.
Before and after are useful observations
If a room becomes uncomfortable or airflow noise changes after furniture moves, include that timing in a service request. Check ordinary obstructions first, then have persistent problems assessed. Clearing one grille does not prove every duct is correctly sized or balanced.
I took a second photograph for the house folder, mostly so I would remember the opening when we next rearranged things. Our dog preferred the new gap beside the sofa. I kept the dog bed out of it, which required more regular negotiation than moving the table.
