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.
The unit hasn t been serviced annually since you purchased it.
While water vapor may not be a direct hazard to human beings like carbon monoxide is when a copious amount of damp warm air begins to fill the home some serious damage can be caused.
Supporters of ventless fireplaces will tell you there are also risks involved with vented fireplaces such as creosote buildup.
Vent free gas fireplace units have also been known to emit water vapor over time.
Vent fee gas logs are not maintenance free.
By contrast vented gas fireplaces which create a dangerously high amount of combustion vent to the outside.
Technically ventless gas fireplaces are safe but you will find just as much resistance to them as you will find supporters.
Ventless gas fireplace safety features that said these gas fireplaces do have several safety features that work to prevent potential issues with carbon monoxide.
Without proper ventilation and safety systems in place there can be serious health risks associated with burning gas in a ventless fireplace.
They must be inspected cleaned annually by a professional gas technician.
Ventless fireplaces produce small amounts of nitrous dioxide and carbon monoxide which can be deadly in large doses.
Ventless gas fireplaces are deemed to operate within the range of safety for cycling combusted gasses back into the home s interior.