There s basically 4 reasons a vent free gas fireplace will produce soot like you described.
Ventless gas fireplace safety.
For instance all gas fireplaces.
Ventless gas fireplaces are deemed to operate within the range of safety for cycling combusted gasses back into the home s interior.
Ventless gas fireplace safety features that said these gas fireplaces do have several safety features that work to prevent potential issues with carbon monoxide.
By contrast vented gas fireplaces which create a dangerously high amount of combustion vent to the outside.
The log s are out of place and are impinging the flames.
Its spent gasses are not returned to the home.
For starters you may start to see your wall paper peel.
Vent free gas fireplace units have also been known to emit water vapor over time.
Technically ventless gas fireplaces are safe but you will find just as much resistance to them as you will find supporters.
Supporters of ventless fireplaces will tell you there are also risks involved with vented fireplaces such as creosote buildup.
Vent fee gas logs are not maintenance free.
Without proper ventilation and safety systems in place there can be serious health risks associated with burning gas in a ventless fireplace.
The unit hasn t been serviced annually since you purchased it.