Shine a light up the flue to make sure there are no raccoons on the damper and smoke shelf.
Smoke in attic from chimney.
When you turn on both fans this will pull out the smoky air while you are drawing in new fresh air.
Next check the chimney flue from the roof or have a chimney sweep do it to make sure no animals are present.
The reason is because when a chimney is being used and smoke is emitted it carries waste particles from the fire.
This is the black smoke you see leaving a chimney when it s in use.
If your flue system is not warm when lighting the fire then you can alter the ability of the fireplace to draw properly creating potentially harmful smoking problems.
These waste particles build up and can get accumulated on the interior walls of the chimney and especially in any cracks there may be in the masonry.
The smell or smoke coming down the chimney is a result of your house loosing too much air from the unsealed attic hatch.
Rerendering may stop the smoke but my advice would be to fit a twin wall stainless steel liner.
Start a small test fire and this time open a window in the same room as the fireplace with the restored chimney.
If you ever had a chimney fire i wouldnt rely on the render stopping further damage.
As soon as the raccoons are gone call a certified chimney sweep to clean your chimney of all nesting debris and install a chimney cap.
That air has to be replenished because your house is not going to implode and so it is going to reenter the house whichever way it can.
This is more likely to happen where a room has an extractor fan for instance and this creates a down draught in the unused chimney strong enough to draw the smoke into that room.
Parging chimney smoke shelves and flues requires special tools and professional training but most homeowners can parge a chimney exterior as it travels through areas such as the basement or attic.
The warm air should rise out of your chimney including the smoke produced.
A warm air siphon must be created before a fire can burn properly and draw correctly.
Now place another fan in a window on the opposite side of the home.
Sometimes it is simply the conditions of the day or the way draughts move around a particular house or the wind being in a particular direction.
