Brenda from Port Hardy, B.C. says that her wood burning insert smells of soot when it is not in use.
The problem is obviously one of air coming down the chimney.
Either the exhaust fans in the house are drawing air when there is no fire to maintain an upward draft, or the wind is twisted around on her roof and comes ramming down the chimney.
Some inserts can be sealed off air tight, but apparently not Brenda's. Aside from solving the problem of the air coming down the chimney, a sooty smell is probably an indication that it is time to have a professional sweep the chimney clean.
Now to stop the air from coming down. When we look at an open fireplace we will see a damper just before the chimney, but that damper never completely closes off the possibility of a draft, and in fact it is removed when an insert is put in. The best product to stop drafts in a fireplace is a Loc-Top cap. It is a spring loaded chimney cover that has a chain that hangs all the way down into the fire box. You pull it shut when you have no fire, and open it when you need it open. There are many cheaper caps that have followed the same idea, but this is the only one that apparently is built right to not freeze shut -- a most frustrating experience in the dead of winter and your fireplace can't be used.
The insert may not be built in such a manner as to allow this chain to hang down, but then again it might, and it would solve that downdraft problem. Talk to your chimney sweep, or call my friends at Aims Chimney Sweep & Hearth Products in Penetang, Ontario.
In any modern wood burning appliance, you should have some way to close it off air tight, either at the bottom or the top, but not leaving the flue open when it is not in use. When this flue is in the basement and this is the first time you have closed it down, check to be sure that the furnace has enough air to function, it may have been getting its combustion air from the fireplace chimney. If the basement is well sealed, you will need to provide some "Combustion Air" for the furnace, and ideally install a combustion air damper to keep it from freezing out the basement.
Now you are getting control of all the air related to your heating devices. Exhaust fans can actually cause air to come down chimneys. Check out "Spillage Susceptible" in the keywords search. And follow this link for more information on wood appliance chimneys,