St. Anne gas logs blackening the fireplace face: rearranged logs and a damper that would not stay open

By Jacob Dove, Friendship Chimney Sweep

Black streaks where there should be none

The house is an older two-story a few blocks from the middle of the village, with a brick fireplace built to burn wood. A previous owner had a vented gas log set installed in the firebox, a common story in St. Anne homes of that age: the masonry stays, the wood pile goes, and a burner pan with ceramic logs takes over. This fall the current owner saw soot spreading up the brick face and smelled exhaust after about an hour of burning. She turned the set off and called us, which is exactly what we would ask anyone to do.

A little soot on the logs themselves is normal with a vented set, because those burners make a tall yellow flame meant to look like a wood fire. Soot on the brick face, the mantel or the glass doors is a different matter. It means combustion products are entering the room instead of going up the flue.

What the soot was telling us

We found two problems feeding each other. The first was log placement. The owner had lifted the logs out in the spring to vacuum the firebox and set them back the way that looked best. Two upper logs were now lying in the flame path. Every set has a placement diagram from the manufacturer, and the gaps between logs are what let the flame rise without touching anything. Flame that washes against a log cools before it finishes burning, and the unburned carbon comes off as soot, along with more carbon monoxide than the set should make. The ember material had also been spread thickly over the burner ports, where dust and pet hair had settled into it.

The second problem was above the firebox. The cast iron throat damper from the wood-burning days had no damper clamp. A vented gas log set sends everything it produces up the chimney, so the damper has to be fixed open, and a small clamp on the plate is what guarantees that. Without one, this damper had drifted half closed. On a still evening the flue could not carry the exhaust away fast enough, and the overflow rolled out under the lintel and painted the brick.

Putting it right

We removed the logs and ember material, cleaned the burner pan and ports, checked the pilot assembly and safety shutoff, and tested the gas connections for leaks. Then we set the logs back to the manufacturer diagram. We do not ask homeowners to adjust gas components, and the same goes for restacking logs from memory: if they have been moved, have the set checked before the next fire.

Next we swept the flue and ran the camera top to bottom. The clay tiles were sound. Had they been cracked, the conversation would have turned to a stainless liner listed to UL 1777. We installed a damper clamp, lit the set, and confirmed with a draft check at the opening that nothing was spilling into the room. We also recommend a carbon monoxide alarm near any fuel-burning fireplace.

Jacob Dove, our founder and team leader with 29 years in the trade, sees this every fall in older village homes around St. Anne where a wood fireplace was converted long ago and the paperwork for the log set is gone. We work to the NFPA 211 standard, we are Insured & Bonded, and tune-up and sweep pricing is published on our pricing page. If your gas logs are leaving soot outside the firebox, leave the set off and call us 7 days a week from 7am to 9pm at (815) 449-4264.

If this sounds like your house: we handle gas fireplace tune-ups across Kankakee County, and our St. Anne page covers what we usually find there. Call (815) 449-4264, 7am to 9pm, any day.

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