If your stove is to function optimally, there must be sufficient oxygen in the room in which it stands. This is not normally a problem in older homes which have not had energy-saving upgrades. Newer homes or homes with energy-saving upgrades can be so airtight that it is not possible to feed the stove enough oxygen for combustion from inside the building. Smoke in your living room when the stove door is opened is one indicator of insufficient air flow to the stove.
Contact your chimney sweeper if you are unsure that your home may be too airtight.
Wood-burning stoves with external air flowIf your home is too airtight and lacks adequate ventilation to maintain combustion, Varde offers a solution for stoves with the option of connecting air flow from outside. This requires the installation of tubing through the outer wall or foundations.
Another option is to install ventilation channels at each end of the room.
If fresh air flow in your home is borderline, be aware that devices such as extractor hoods, ventilators etc. can interfere with air supply so much that your stove will not function optimally. This can also mean that smoke escapes into your living room when the stove door is opened.