Fireplace damper (C) Daniel Friedman Fireplace & Chimney Dampers
Fireplace damper inspection, operation, & repair

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Fireplace Dampers: construction, inspection operation & repair:

What is a fireplace damper, where is it found and how should you use it? When should the damper be opened, closed, or adjusted? Fireplace dampers can rust, break, crack or collapse, leading to increased building heating costs, invasion by pests, and other trouble. Here we explain how to inspect & repair fireplace dampers.

This article series provides information about masonry fireplaces, including inspection for damage/hazards (cracks and gaps that appear at masonry fireplaces due to chimney or fireplace settlement or movement), fireplace chimney sizing requirements, draft problems, chimney safety, creosote problems, inserts, and other topics.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Fireplace Damper Trouble Inspection, Diagnosis, Repair

A fireplace damper is a metal door installed in the fireplace chimney throat. To avoid wasting building heat by sending it up the chimney when a fireplace is not in use, the fireplace damper door is closed when the fireplace is not in use.

Fireplace schematic

[Click to enlarge any image]

In the sketch above you can see the position of a fireplace damper in the fireplace below the smoke shelf and labeled "damper". In this drawing the fireplace door is in the open position. Just below we show a horrible excuse for a fireplace damper: a pillow stuffed into the fireplace throat, and at below right we show a normal, closed fireplace damper door. Note that the dimensions given in this sketch are recommendations and not "building code".

Our sketch below, provided by Carson Dunlop Associates and used with permission, shows the location of a fireplace damper in the chimney flue where a woodstove or fireplace insert has also been installed.

Fireplace damper sketch showing the location of the damper where a fireplace insert was installed (C) Carson Dunlop Associates, used with permission by

[Click to enlarge any image]

Fireplace Damper Inspection

Inspect fireplaces for a working damper. Check that the damper door will open and close properly, that all parts are present, and that the damper is intact, that is not broken nor perforated by rust.

Where a steel insert fireplace is installed, inspect the upper portions of the fireplace at the chimney throat with great care. A rusted-out steel fireplace inset will be unsafe, wont' work properly, and will be costly to replace.

Pillow used as fireplace damper (C) Daniel Friedman

Stuffing a pillow into the chimney throat of a fireplace (above) might slow the loss of warm air from a home, but it's a dangerous substitute for a missing or broken fireplace damper. What if someone lights a fire without noticing this stuffing?

Fireplace damper (C) Daniel Friedman

A normal cast iron fireplace damper is shown in closed position in our photo above. Closing the damper when the fireplace is not in use will make a significant reduction in heat loss from most buildings.

Steel fireplace insert under construction (C) Daniel Friedman

Our photograph just above shows a steel fireplace insert at an incomplete fireplace installation in a basement. What about that plywood "face" nailed around the steel fire chamber?

Replacement Fireplace Dampers Seal at the Chimney Top

If the damper at your masonry fireplace has been lost, rusted away, cracked or is otherwise missing or damaged beyond repair, it may be possible to install a chimney-top damper to achieve the same fireplace and draft controls you need to avoid sending building heat up the chimney unnecessarily.

Chimney top seal damper from  Woodland Direct can replace a lost or rusted-out  fireplace damper -

A top sealing chimney damper is typically made of cast-iron and is cemented in place at the top of the chimney flue. The usually-separate chimney rain cap is also required, remains in place, and must not obstruct or interfere with operation of the damper.

Illustrated just above and in more detail below is a cast iron retrofit chimney top seal damper distributed by Woodland Direct, a fireplace and chimney and woodstove supplier. We give contact information for the company below.

Chimney top seal damper from  Woodland Direct can replace a lost or rusted-out  fireplace damper -

A chimney-top replacement damper is typically a hinged metal door installed at the top of the chimney - working from the rooftop. A cable extends down the chimney flue and into the fireplace opening where - when the fire is not burning, the damper can be opened or closed by pulling and latching the operating cable.

Chimney top seal damper from  Woodland Direct can replace a lost or rusted-out  fireplace damper -

Watch out: OPINION: some spring-operated chimney top dampers use a movable rain cap supported on wire arms that lift the cap up or close it down over the chimney flue. This type of cap may be suitable for gas-burning appliances, but as it omits any fire screen it may not be safe nor approved for chimney flues serving wood burning fireplaces.

Woodland chimney top seal spring operated damper - at

For more details about regulating draft at any fuel-burning appliance, see DRAFT REGULATOR, DAMPER, BOOSTER.

Chimney Top Damper Suppliers

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Publisher - Daniel Friedman