How do I check whether my damper is fully open before lighting a fire?
Look at the damper handle or control to see which way it is set, then shine a torch up from the hearth and look for the damper plate tilted back out of the way. You should see a wide, clear opening into the flue, not a flat metal plate across it.
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The handle alone can mislead you. If the linkage is worn or the plate is jammed with soot or rust, the handle can move while the plate stays put, so always confirm by looking.
Why a damper looks open when it isn't
A damper is a metal plate that sits in the throat of the fireplace, just above the firebox. Closed, it stops heat escaping up the chimney. Open, it lets smoke and combustion gases leave. A plate that is only part-way open restricts that flow, and smoke can spill into the room.
Dampers are operated by a lever, a knob, a chain or a poker-operated handle. Over time the hinge or linkage can rust, bend or clog with soot and debris. The control then shows one position while the plate sits in another, or it moves only part of the way.
A fully open damper does not guarantee a good draft. A blocked flue, a clogged cap, a cold flue or a smoke chamber full of debris can all push smoke into the room even when the plate is wide open. If the damper checks out and smoke still comes in, the cause is further up.
What you can check yourself
Do it with the fireplace cold
Check before any fire is lit, once the firebox and ashes are completely cold. Never test a damper with embers in the grate.
Find and read the control
Locate the lever, knob, chain or poker handle and note which way it is set. Move it through its full travel and listen for a metal plate moving, rather than a loose rattle or nothing at all.
Look up with a torch
Stand at the hearth and shine a torch up into the throat. The plate should be tilted back, leaving a wide gap you can see through. Keep your hands and tools out of the flue.
Notice resistance or grinding
A handle that is stiff, gritty or stops short usually means rust or soot buildup around the hinge. Do not force it hard enough to bend the linkage.
Check the alarms
Make sure the carbon monoxide and smoke alarms near the fireplace have working batteries before any fire is lit.
When to call a technician
If the damper won't open fully, the plate looks warped or broken, or the handle moves but the plate doesn't, stop there and don't light a fire. Also stop if the damper is fully open and smoke still comes into the room. If you are already in that situation, put the fire out, open a window, and if anyone feels headachy or dizzy, get outside and call 911.
One Call Chimney is a referral and scheduling service. One call to (866) 576-7943 arranges an independent chimney technician. They inspect the chimney, give you the price, and start work only once you have approved it. The estimate is free. Whether a damper repair or replacement needs a permit varies by area, so check with your local building department.
What the technician will do
- Sweep and camera-inspect the flueThe flue is swept and a camera is run through it to find any blockage. Ask to see the footage.
- Free, repair or replace the damperA stuck damper is freed where possible. A damaged one is repaired or replaced, depending on what is found.
- Test the draft and find the causeThe technician tests how the chimney draws and identifies why smoke was coming into the room. Ask for the reasoning in writing.
- Check the cap and crownThe cap and crown at the top are checked, since a blocked or damaged cap can mimic a damper problem.
- Clean and parge the smoke chamberThe smoke chamber above the damper is cleaned and parged where needed so gases flow smoothly into the flue.
Related questions
- Can I tell if the damper is open by feeling for air?
- Not reliably. Air movement in a cold chimney can go up, down or nowhere, depending on temperature and the pressure inside the house. Looking at the plate with a torch is more dependable.
- What if the damper is open but smoke still comes into the room?
- Put the fire out and open a window. The cause is probably elsewhere: a blocked flue, a clogged cap, a debris-filled smoke chamber or a draft problem. A technician can find it with a camera inspection.
- Should I leave the damper open when the fireplace isn't in use?
- A closed damper limits heat loss and keeps drafts out, so close it once the fire is completely out and cold. Always reopen it fully and check it before the next fire.
- Can I oil a stiff damper myself?
- Heavy soot and rust are better dealt with by a technician, who can clear the hinge and linkage properly. Forcing it can bend the plate or break the handle, which makes the repair bigger.
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