I have the same brand of chimney and so does my neighbor, we both had to modify the cap on the top of it.
Mine pulled ok draft and didnt puff smoke into the house but plugged up quick, mine's straight up through the ceiling. His is set up just like yours and puffed smoke out the door when putting wood into the stove and really plugged up quick no matter how hot you run the stove.
To test this theory take the cap off and light the stove.
To modify the cap we took an angle grinder and cut the bottom half of the band around the outside of it off, this lets the smoke go almost straight out the side.
I havent had to clean my cap since I modded it, before I had to clean it monthly, it's a horrible cap design. My old chimney cap never had this issue, all I changed was the pipe and cap in my house due to age and then I had issues with the cap.
Mine pulled ok draft and didnt puff smoke into the house but plugged up quick, mine's straight up through the ceiling. His is set up just like yours and puffed smoke out the door when putting wood into the stove and really plugged up quick no matter how hot you run the stove.
To test this theory take the cap off and light the stove.
To modify the cap we took an angle grinder and cut the bottom half of the band around the outside of it off, this lets the smoke go almost straight out the side.
I havent had to clean my cap since I modded it, before I had to clean it monthly, it's a horrible cap design. My old chimney cap never had this issue, all I changed was the pipe and cap in my house due to age and then I had issues with the cap.