Hello. I live in a twin home and our fireplaces share a chimney. The top of our flue is shorter than the neighbors flue. Would this cause our fireplace to smoke?
Is your fireplace smoking now? Because I've seen many setups such as yours. If your fireplace smokes, open a window a small amount to create a draft so the smoke rises. If the home is a newer home they are built so airtight you need some air movement to have a good fire.
You don't say how old your house is. If it is an older house, check the brickwork on the top of your chimney to make sure it doesn't need repair. If it is leaking, the fire may not draw properly. Also check the cap on the chimney to ensure that it is properly placed, as some older houses have caps that open from inside the fireplace. Finally, if you haven't had the chimney cleaned lately, having it thoroughly cleaned would also be a good idea.
If none of these things works, and the flue is functioning properly, you can try a smoke guard over the front of the fireplace.
Even if your house is a newer model, it always pays to have the chimney cleaned and checked annually. The sweeps know a lot about how fireplaces function and could probably help you out.
if your fireplace is drawing smoke in when your neghbor is burning a fire use a chimney balloon to seal the flue tighter than your metal damper will.
If your fireplace is smoking when you are burning a fire in your fireplace it is probubly because your home is so tight you cant get the air movement stack effect going. Opening a window a bit will work, but on a cold winter day who wants to do that?! My suggestion is make sure you have glass doors and you use them. Most glass doors have a lower vent you can adjust to allow the fire to draw heat from the floor.
Here is a link that might be useful: Chimney Balloon to stop smokey chimney