The first thing you should do is make sure that your chimney is clean. If it’s not, the smoke from your Gas Logs will be coming back into your house. Once the chimney is cleaned, there are a few other things you can check:
Are the logs placed properly in the fireplace? They should be placed on the grate with plenty of air space around them.
Are the flue dampers open? They should be opened all the way when you have a fire going.
Is there anything blocking the airflow to the fireplace? This could be something as simple as a curtain that’s been drawn too close to the fireplace.
