The company that installed the gas insert should have removed the damper handle in the original wood burning fireplace. As they slid the insert into the wood firebox the damper crushed the vent pipe causing a considerable reduction in the fireplaces' ability to draw properly. The reduced ability to draw caused the fireplace to trip the spill switch (safety feature) and shut off, preventing carbon monoxide from venting into the home. Instead of fixing the venting problem, the service technician pulled the wires off of the safety feature (spill switch) and wired across it, creating an extremely dangerous and possible life threatening situation. The fireplace worked, but without the spill switch to detect unsafe conditions, the gas fireplace spilled dangerous carbon monoxide and carbon into the house for the next 4 years. People have died from situations like this.

Make sure to have a professional service your gas appliances and take the time to check that your service technician is certified and well known in your community. Always have carbon monoxide detectors installed throughout your home,  at a minimum, change the batteries yearly.