Wood heaters provide natural and comforting heat but when the flue is blocked by the damper, the smoke and harmful gasses from the fire cannot be drawn through to the outside world and instead may fill your house.
Here's how to check if the damper is open:
1. Light a small fire and check the draw
Lighting a small fire eliminates the chance of a lot of smoke filling the room and is the easiest way to check the damper. If the flue is not blocked, the smoke will be drawn up into the chimney. If the damper is closed, the smoke may come out of the wood heater and fill the room.
2. Check flue and damper
Actively look up into the chimney with a flashlight or phone torch. If you can see sky coming through, the damper is open. Sometimes a chimney has a cap, so you might have to view it from the outside rather than inside the wood heater. If you cannot see the sky and your chimney doesn't have a cap, either the damper is closed or something is clogging the chimney (oftentimes this is leaves).
3. Air circulation
Place your hand under the flue and see if you can feel a breeze. While it's not the most effective way of checking, it can be the quickest. If you can feel a breeze, the flue shouldn't be blocked by a damper or debris that has fallen into the chimney.
4. Check damper controls
Damper controls determine the amount of air that can get through the flue. To see the damper, merely stick a torch inside the chimney and look for the cap closest to the wood heater. Open it wider if you have trouble with the flue's draw.
Wood heaters are great for natural warmth. Knowing how to check the damper's position will help you avoid smoke and harmful gasses filling your home. You can check by lighting a small fire to see the smoke draw, actively checking the flue and dampeners for blockage, feeling under the flue for air circulation, and ensuring the dampener is in the correct position.