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Gas insert fireplace


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I inspected a house today that had a gas insert fireplace. The first thing that i noticed was a whitie haze in the glass, similar to that of a broken window seal. I turned the fireplace on thinking that the heat of the flame would evaporate the moisture, but after 10 minutes or so the haze was still there. I could see the haze moving, but not burning off. Are there typically two panes of glass, and moisture got in between the two like a broken seal in a window? It was about 20 degrees this morning, and it had a metal chimney (under siding), not a side wall flue.

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What you saw is reasonably normal, it happens after a few years of use. Natural gas has a high moisture content; when the fireplace is turned on, condensation can form on the interior of the glass (usually single pane). This is due to the fact that the temperature of the glass is cooler than that of the flame/interior. This condensation leaves a residue when it evaporates. The white haze builds up over time. It can be cleaned by removing the glass panel and using a special cleaner. Call a fireplace shop to get the correct cleaner. I'm under the impression that Windex and cleaners of that type will leave a bad residue on the glass when they get hot.

BTW, we should move this to the fireplace forum

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The haze is sulfur particles. As previous folks have said, the glass is cooler than the air in the fireplace, when you fire it up, the flame gives off water, nitrogen, sulfur and other particulates that cling to the damp glass and over time build up. Ignore it long enough and those blue sulfur particulates eventually turn the glass from white to blue. As it does to a chimney and firebox, it will eventually etch the glass if ignored.

They make a wax that's really good for cleaning a glass top range and I've found that it works equally well for removing the sulfur stains from the fireplace front glass. I bought a bottle at Ace Hardware.



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