Hi and Welcome to Just Answer,
Ok, let's take a look at this;
Back draft is caused by a fire losing its oxygen to burn properly, then once the oxygen is introduced, it can explode.
To prevent back draft on your fireplace, you just make sure that you have a chase to allow oxygen to get to the fire.
If you have an older fireplace, some chases (if they even have one) is outside, this causes heat loss. One solution is to move the chase inside and to vent it to the interior so warm air can circulate (middle).
The damper needs to be open to help create a draft.
My fireplace is open, so mainly all I need to do is open the damper and leave my glass doors open, this allows the fire to breath
If you need more help Let me know
If you find this post helpful please take a few minutes to leave Feedback.
By you leaving Positive Feedback you give your Expert additional opportunities to earn extra CASH and Recognition.
If you would like to give a Bonus they are always welcome.