I moved into a house with a vented gas fireplace and gas logs. Beneath the grate holding up the logs there were vermiculite granules in a pan which covered the gas vents.
My wife wanted me to remove the vermiculite since she didn't like how it looked, and wanted to use the fireplace without it.
When I run the fireplace the flame jets exhaust downward on either side of the feed pipe, hitting the pan (now with no vermiculite in it).
Is it safe to run the fireplace like this, or should I put vermiculite back in it?