That's a tough one. Well to start I have 3 cats and one bathroom and small 2 bedroom. I use a lot of incense. But your problem is different, you see you're sense of smell has gotten use to the parrot's odor. Just like smokers, they've smoke for so long cigarette smoke doesn't bother them and it's a normal smell , but it sickens me and my taste buds. He lives upstairs, and the odor travels through his ventilation ducts. It's like living next to a smoker. I had a friend who had 3 parrots but she owned her on home. Cacocobird, I'm afraid you may have to move.

Am getting room freshener that is parrot safe, and doing a better job of cleaning up the bird area. We have smoothed things over.

Parrots are messy birds, I clean my conure's cage every morning..

The heating system may be linked between the two units. There may be an intake vent drawing air into the system and blowing it into his unit. Ask him to consult an HVAC technician to remedy this situation