Why Does My Fireplace Fog Up When I Turn It On for the First Time?

Why Does My Fireplace Fog Up When I Turn It On for the First Time?

When starting a fireplace, many of us experience condensation or fog on the glass for the first few moments. This shouldn’t cause any concern as it is part of the normal process of condensation that occurs when water vapor condenses onto a cool surface.

Condensation Process

There is always moisture in the air. This moisture is measured as a percentage of the total amount that the air will hold at a specific temperature, which is known as relative humidity. There is more moisture in warmer air and less moisture in cooler air.

When invisible water vapor completely saturates the air and the vapor starts to become dew or visible water, this is known as the dew point. When the dew point is high, the air feels damp and wet, and the relative humidity is high. When the outside air temperature drops below the dew point, rain or fog appears.

When the temperature of the glass on the front of the fireplace inside the home drops below the dew point of the inside air, visible moisture forms on the glass. The combination of a cool glass surface and a high level of moisture in the air triggers the condensation process. There can be increased condensation when there is more moisture in the air and/or when the surface on the glass of the fireplace becomes colder. Once the fireplace heats up, the fog or condensation will evaporate in a short period of time.

Reducing Moisture Levels

Kozy Heat recommends several ways that water in its different forms—moisture, fog, steam, and water vapor—can be reduced in the home.

Cooking, washing, showers and similar activities can add lots of moisture to the air. Plumbing leaks, damp basements, pets and plants, however, can begin to introduce moisture problems.

To correct these issues, cover any soil on bare crawl spaces with a plastic vapor barrier. Fix any grading and drainage problems so that water freely flows away from the home. Basement walls and floors should be sealed and basement sump pumps should keep the water level 8 to 12 inches below the basement floor.

The professionals at Kozy Heat can help you with moisture problems in your home and ensure that the glass on your fireplace is always clean and clear and also enhances the appearance of your fireplace flames.