How to Control a Fireplace Damper

A fireplace damper doesn't work in isolation but is one component of a system that functions (or malfunctions) collectively. It can help regulate the fire's intensity, but no amount of damper control will tame a poorly designed and poorly functioning fireplace. There are, however, steps you can take to determine how much the damper is influencing your fire. The smoke alarms might go off during this procedure but as long as the smoke is originating only from back-drafting out of the fireplace and you're tending to the situation, you'll know there's no safety concern.

Difficulty: Moderate

Instructions

Things You'll Need:

• Type of wood you normally burn in the fireplace Helper

1. Pick a time when the fewest occupants will be in the house and start a fire in the fireplace. Regardless of other circumstances, starting a fire should always be done with the damper in the fully opened position.

2. Experiment with the damper by trying it in different positions. Do this during different stages of the fire. Begin early in a newly lit fire. Adjust again in the middle stages after a fire has been burning for a while. Finally, adjust the damper later when the fire has a fairly thick bed of coals.

3. Have a helper keep an eye on the fire then go outside and check conditions, making note of the temperature, wind speed and wind direction. All these factors will affect how a fireplace behaves.

4. Return to the inside and observe what the fire is doing. Adjust the damper to a more open setting if the fireplace is smoking into the room even slightly.

5. Get comfortable with operating the damper under the current set of conditions.

6. Repeat the previous steps at different times under different conditions of temperature and wind.

Tips & Warnings

• A fireplace and its damper will function differently under different conditions. Factors that influence how a damper, and the fireplace in general, will perform include the inside and outside temperatures, wind, type of firewood, the landscape surrounding your house (including hills and trees) and the moisture content of the firewood. Trees near the house can cause wind currents to swirl around and interfere with the column of smoke coming out of the chimney, creating a back-draft. Sometimes removing problem trees can transform a poorly performing chimney. Some fireplace designs are very forgiving and virtually any damper setting under all sorts of conditions will work just fine. Others might be very finicky and the slightest nuance could make them misbehave. It's really a matter of experimenting and getting to know your particular fireplace and its characteristics. A newly lit fire---even with dry wood---will tent to generate more smoke than a well established fire. So an open damper is always best when starting the fire. Damp or wet firewood will tend to misbehave regardless of damper settings.
• All the usual precautions in operating a fireplace should be observed. Other than the possibility of getting some smoke in the house when trying different damper settings, there should be little risk involved. The exception would be that humans or pets who may have respiratory problems should not be present while you are following these steps.