Just light a match and hold it near the flue.
If the the air is going up the chimney you will see the flame drawn in that direction.
A flue-gas analysis kit may contain a gas detector for measuring gas concentrations, a temperature probe for measuring flue gas temperature, and a draft gauge for measuring draft pressure in the flue.
flue gas out
The glass on a wood stove will get dirty because of creosote deposits - smoke. The solution is to aim for a cleaner burn, which might mean going to a cleaner burning wood, better seasoned wood, or increasing the draft and letting the stove burn hotter. You should also check the flue system and chimney to see that they are clean and free of obstructions, including both creosote and little piles of ash built up in such places as bends of the pipe.
To open a flue properly for ventilation and safety, first locate the flue handle or lever near the fireplace or stove. Pull the handle or push the lever to open the flue completely. This allows smoke and gases to escape through the chimney, preventing buildup indoors. Make sure to keep the flue open while using the fireplace or stove and close it when not in use to prevent drafts and energy loss. Regularly inspect and clean the flue to ensure it functions properly.
To determine if the flue is open, you can look up into the fireplace or stove chimney to see if the flue is clear and unobstructed. You can also feel for airflow coming down the chimney when a fire is not burning. If you feel air coming down, the flue is likely open.
You should change the flue if you have ever had a flue fire. you also can remove the base T and use a mirror to look up the flue. If the inside looks warped it should be replaced.
To open the chimney flue, locate the handle or lever typically found near the fireplace or stove. Pull or push the handle in the direction indicated to open the flue, allowing smoke and gases to escape through the chimney.
To open a chimney flue, locate the handle or lever typically found near the fireplace or stove. Pull or push the handle to open the flue, allowing air to flow through the chimney. Make sure the flue is fully open before starting a fire to ensure proper ventilation.
if you are talking a stove flue [free standing] the handle on the flue will indicate open or closed. if handle is horizontal flue is closed. if vertical flue is open. if you mean fireplace flue usually pushing flue handle to rear or back of fireplace will open it and pulling it toward you will close it. you can check by moving handle slowly while looking with flashlight up in the chimney. be careful as soot can come down and out if you get too aggresive.
To install a stove pipe for a wood stove in your home, first measure the distance from the stove to the ceiling or wall. Purchase the appropriate size and type of stove pipe. Connect the pipe to the stove's flue collar and secure it with screws. Extend the pipe through the ceiling or wall, ensuring it is properly supported and has the correct clearance from combustible materials. Install a thimble where the pipe exits the wall or ceiling for safety. Finally, connect the pipe to the chimney or flue and ensure it is properly sealed to prevent leaks.
The air flow up your chimney that carries the products of combustion (flue gases) out of your house.
Try sweeping the flue - it is probably choked with soot.