smell from muti fuel stove

[morveng]

Our Multifuel stove is in use for the 2nd autumn and it still produces a smell after about an hour from being lit when it gets hot. We are burning seasoned timber and the stove was fitted by a reliable company. The flue runs from the top of stove through ceiling then through roof, is it normal for twin wall insulated flue to be fitted directly into stove? The odour does resemble the new stove smell but this should have gone by now.