How to Open a Chimney Flue?

Chimney (5)

A chimney damper serves the purpose of preventing your home’s conditioned air, whether it’s heated or cooled, from escaping through the flue when the fireplace isn’t in operation. For proper airflow and to allow smoke to exit, it’s essential to open the damper when lighting a fire.

Leaving the damper closed could restrict airflow, potentially leading to a safety hazard as smoke could build up in your house. Here’s some guidance on how to determine if your damper is in the open or closed position.

What Type of Damper Do You Have?

There are primarily two types of chimney dampers. To determine whether your damper is open or closed, start by identifying the specific kind of damper installed in your chimney.

Throat Damper

Throat dampers are popular owing to their convenience. They seal off the base of your chimney, thereby insulating your home from cold drafts. Given its location within the fireplace, it’s straightforward to determine whether a throat damper is open or closed, as it can be viewed at the firebox’s top.

Throat Damper

Throat dampers are popular owing to their convenience. They seal off the base of your chimney, thereby insulating your home from cold drafts. Given its location within the fireplace, it’s straightforward to determine whether a throat damper is open or closed, as it can be viewed at the firebox’s top.

The upper section of the firebrick lining the back of your fireplace should have a minor inclination. This guides smoke upwards and outwards while minimizing cold air intake, and it may lean towards the throat damper. This damper, situated at the firebox’s peak, swings downward to close the throat when the fireplace is not in use. Most dampers are made of cast iron or steel and will appear black or rust-colored.

To feel the damper, you can reach inside the fireplace opening and behind the lintel. You should be able to manipulate it open and shut using a knob (typically found on the fireplace’s front face) or rod (located in the fireplace, above the firebox).

Top-Mount Damper

A top-mount damper provides a seal for the chimney cap, thereby insulating the entire chimney flue. One benefit of a top-mount damper compared to a throat-mounted one is its ability to stop animals and debris from dropping into the flue.

Typically, a spring holds the top-mount damper open, with the control cable or handle often affixed to the wall of the fireplace. The default position of this damper is open, so you’ll need to pull a chain or cable against the spring’s resistance to close the damper.

Top Mount Damper

How to Know if the Damper is Open

Determining whether a damper is open or closed depends on its type. Starting a fire with a closed damper can rapidly fill your house with smoke. For safety, it’s advisable to make a routine of verifying the damper’s status before igniting a fire.

Below are various techniques you can employ to ascertain if the damper is in an open or closed state.

Feel for a Draft

With an open damper, air can flow unimpeded in the chimney flue. If you place your hand or face into the fireplace, you should be able to sense the cold air.

Please remember that this method may not be entirely accurate if you have a top-mount damper. The chilly air accumulated in the chimney flue could lead you to erroneously believe the damper is open.

Visually Check

One of the most reliable methods to determine if the damper is open or closed is a visual inspection. Simply position your head inside the fireplace and look upwards.

For a throat damper, a closed damper directly above your head will obstruct your view. You should be able to extend your hand upward and feel the closed damper.

In the case of a top-mount damper, look for signs of daylight at the flue’s top. If there is no daylight visible at the top, it indicates that the damper is shut.

Check the Controls

The current alignment of the control mechanisms (like a cable, rod, or handle) can aid in identifying whether the damper is open or closed, provided you’re well-acquainted with the chimney and its controls. However, if you find yourself in a house that’s new to you, it’s advisable to conduct a visual inspection after examining the position of the controls.

Do Not Start a Fire in the Fireplace if You Are Not Sure the Damper is Open

Certain resources suggest that initiating a fire in your fireplace can indicate whether your damper is open or closed. However, this method is highly hazardous if the damper is shut and should never be utilized for testing.

Having your home filled with smoke is more than just an inconvenient situation. It poses risks to your home’s interior, personal possessions, and most crucially, your health, especially when a shut damper traps smoke indoors.

If you ever light a fire without confirming the damper’s open position, monitor the flames and smoke closely. Open the damper immediately if you observe insufficient airflow.

With a closed throat damper, the onset of a fire will instantly fill your home with smoke. If your chimney has a closed top-mount damper, it might take a few minutes before smoke begins to permeate your house, but eventually, you’ll notice a lack of sufficient airflow.

How to Check the Controls and Open a Damper

Before starting a fire, it is advisable to always check the controls. This is because even if you can feel a draft, a partially open damper can hinder proper airflow. By doing so, you ensure optimal ventilation and a safer fire experience.

Different Types of Controls

Throat dampers usually feature a rod, which, when pushed or lifted, adjusts the damper’s position.

Certain chimneys have a knob that twists a rod to modify the damper. Typically, these knobs are located on the fireplace’s exterior, often centered above the fireplace opening, though sometimes they can be found to the side.

Top-mount dampers operate on a spring-loaded mechanism. They stay open until a chain or handle, typically installed on the firebox’s side, is pulled to close them and lock the mechanism, ensuring the damper remains closed.

If the chain or handle isn’t securely fastened in the bracket, it signifies that the damper is open.

How to Open a Damper

If your throat damper has a rod control within the fireplace, try pushing or lifting the rod further to check its status. An external knob control on the fireplace can be slightly more challenging to figure out as it might be unclear which way to turn it.

A simple solution exists: Rotate the knob fully in one direction and peek into the fireplace to inspect the damper’s position. This method easily determines which direction opens and closes the damper, especially if the knob lacks index markings.

For a top-mount damper, pull the chain downwards to see if you can shut the damper. If the chain isn’t secured, the damper will instantly spring back up. This exercise is helpful to perform before lighting a fire to ensure that the top-mount damper is fully open.

As you become more familiar with your chimney, identifying whether a damper is open or closed will become easier. Once accustomed to your chimney and the usual draft from the flue, you should quickly notice if there’s insufficient airflow. Remember to close the damper to conserve your home’s conditioned (heated or cooled) air when the fireplace is not in use.