What’s the purpose of a damper in my fireplace? Should it be open, closed or partly open when I build a fire? What do I do if it’s an older fireplace and the damper doesn’t operate correctly? For these answers and more, keep reading.
WHAT IS IT?
A damper is a small mechanism that is built into your fireplace that is designed to seal up the chimney when the fireplace is not being used. This is done to prevent warm, interior air in the house from being pulled into the firebox and up the chimney. Think of the damper as a mini door, that when closed, separates the firebox from the chimney. One way or another, you have paid to heat the air in your home. So, let’s not lose it by leaving the damper open when there is no fire in the fireplace.
If a damper is not opened when a fire is built, smoke will back up quickly and fill the room. Guaranteed! So, you always want to check to make sure the damper is completely open when a new fire is built.
OPEN OR CLOSED?
The best way to check for an open damper is to simply look inside at the top of the firebox. Do this before you get a fire going! If it’s open, you should be able to see up the chimney. If the chimney is offset you might not be able to see all the way up it, but you’ll be able to see at least part way. If the damper is closed, it should be quite obvious because the chimney will not be visible at all.
Some dampers are cast iron and operate on a worm gear mechanism. Some will pivot open and closed by moving a lever forward and backward. Others might slide on a rod or bar. Regardless of how they open and close, make sure the damper is fully open before you light the kindling and get a fire established.
A fireplace damper should always be kept open while the fire is burning. Furthermore, keep the damper open until all the embers are completely out. Smoke and dangerous carbon monoxide can enter the house. Once the ember bed is completely out, close the damper. You may want to wear a heavy leather glove, since the damper could still be quite hot. It will definitely be dirty from soot. By closing the damper, the warm air from your living room is not lost up the chimney.
Every year, WE LOVE FIRE experts get phone calls that go something like this: “Why does my living room cool off so fast and the furnace seems to run more when I get a fire going? Shouldn’t my house stay warmer after a fire? My family room feels drafty.” Odds are, the answer to these questions is that the fire has gone out and the damper was left open. By leaving the damper open, heat is being lost. Essentially, warm air is being pulled through a large hole in your living room ceiling. It’s called the chimney!
DOES MY FIREPLACE OR STOVE HAVE A DAMPER?
Some, but not all, zero clearance, factory-built fireplaces have dampers. All masonry fireplaces should have a damper.
Generally speaking, if your fireplace is designed with gasketed, ceramic glass doors, it will not have a damper. EPA certified fireplaces and stoves are designed to be burned with the doors closed tight. EPA certified fireplaces have primary air controls that will allow a specific volume of air into the firebox for efficient combustion to occur. In essence, the chimney is always “open” and cannot be closed off with a damper. However, the sealed, gasketed doors prevent air leakage and smoke from entering the room.
The primary air control is used to control the burn rate. More air to the fire, means more heat into the room and shorted burn times for the wood. Reducing the amount of combustion air results in longer burn times and less heat.
If you own an older stove or fireplace, perhaps one with bi-fold doors, there should be a damper that can be opened and closed. These are not sealed up or gasketed units. The air control over the burn rate is usually not too precise. And, efficiencies for this type of equipment are not rated, but are very low compared to an EPA certified model.
AIR CONTROL VS. DAMPER
Do not confuse the primary air control with the damper. There are separate and distinct functions for both. The primary air control will control the burn rate. How hot or lively the fire is, and how much heat is produced, is determined by the air control. Remember, the damper opens and closes the chimney flue to create the draft that’s necessary for the smoke to be pulled up and out of the firebox. The air control determines the burn rate.
DAMPERS FOR FREE-STANDING STOVES
Dampers installed in wood stove connector pipes is old, outdated technology. They are not recommended with today’s equipment. Manufacturers design stoves that are easy to operate. Today, we control the amount of air into the stove, not the amount of air out by placing a restriction or damper in the connector pipe!
Heat reclaimers, available from some online sites, are designed for pulling heat out from the black connector pipe of a wood stove. Most hearth dealers would advise against using these devices. They can lead to creosote quickly forming in the chimney because of significant heat being removed from the connector pipe.
WHAT ABOUT GAS LOGS AND THE DAMPER?
Decorative gas logs in fireplaces are very popular today. Does the damper need to be open when using gas logs? It depends on local codes in your area and the type of gas logs installed.
Vented Gas Logs: Since the pilot light runs continuously, a small C-Clamp must be installed to keep the damper slightly ajar. When the logs are burning, you should have the damper fully open.
Unvented Gas Logs: You can operate unvented gas logs with the damper closed. Unvented logs are primarily for decoration since they provide little heat. However, also likely to add considerable moisture to your room. Some unvented equipment may cause odors in the home, too. Because of the moisture and odors, many dealers and manufacturers recommend operating unvented gas logs for only a couple of hours. Before you go the unvented route, be sure to check your local codes. Some areas do not allow them.
HELP! WHAT DO I DO? MINE’S BROKEN!
If the original damper for your fireplace is missing or beyond repair, your WE LOVE FIRE expert will likely recommend a lock top sealing damper. Basically, this type of damper is a spring-loaded cap installed on the top of the chimney. A cable is installed into the firebox. When operated, the cable springs the cap up to open, or down to close up the chimney. These are quite effective at thoroughly sealing up the flue and preventing the loss of warm air when the fireplace is not in use. If yours needs replacing, this is a project that should probably be evaluated by a professional.
Remember that your WE LOVE FIRE dealer is a terrific resource and we’re here to help in any way we can.
LET’S SUMMARIZE
Before you start a wood fire, always fully open the damper. Keep the damper fully open until all the embers are completely burned out. If you have a vented gas log set in your fireplace, turn off the flames before closing the damper as far as the safety C-Clamp allows. The damper can be fully closed if yours is an unvented gas log. Again, be aware of the moisture and odors concerns with unvented equipment.
If there is no fire in your fireplace, it’s good practice to keep the damper closed to prevent air infiltration and heat from being lost up the chimney.
Using a damper is a simple concept. Not using it correctly or forgetting about it can have serious consequences that can put your loved ones and property at risk.
Better to contact your local WE LOVE FIRE expert for your annual fireplace inspection. They can spot any damage and provide recommendations for the safe enjoyment of your fireplace.
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