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Michael Chambers
07-19-2011, 09:44 AM
Why would a chimney top damper be installed for a fireplace that has a regular damper that appears to be working fine? Thanks for your help with this!

Scott Patterson
07-19-2011, 12:03 PM
Why would a chimney top damper be installed for a fireplace that has a regular damper that appears to be working fine? Thanks for your help with this!

Keep wind out, wind driven rain or critters out?

That is really a crystal ball question! :)

Bob Harper
07-19-2011, 03:49 PM
Top dampers usually seal better so they are often sold for energy conservation.

Throat dampers offer severe flow restriction so a lot of contractors are blowing out those metallic throat dampers, "Rumford-izing the throat and smoke chamber then mounting a Top Sealing Damper (TSD).

Some sweeps suggest allowing warm room air to 'prime' the chimney all the way to the top before opening the TSD then lightnig the fire to minimize smoking problems.

TSDs can act as a rain cap/ animal guard either as the TSD itself or when built into a typical ss cap w/ screening.

TSDs are a lot cheaper to install than busting out and replacing a damaged or missing throat damper.

When you reline a fireplace, it is the practical solution because it allows you to blow out that darned throat damper, which hinders flow anyway and, once gone, allows access into the smoke chamber to make a better repair.

TSDs are much easier and convenient to operate. You reach into the firebox and grab the control which is in plain sight. No sooted up handle which you use *feel-a-vision* to find it. No more wrestling with an swkward control that is out of your vision or which forces you to kneel down and crank your face up into the throat often sooting your face up. No more pushing against a damper plate blocked by dead critters, live critters, and debris.

If you want to keep out stink bugs and don't have a listed fireplace, consider installing a TSD.

Note that a few TSDs are known to downsize the flue, which can lead to smoke spillage problems. This same design can also make a very effective squirrel trap so I recommend against them.

People often forget to close their dampers. TSDs are visible both from the yard and the room it serves. You can easily tell if it was left open with a glance.

TSDs are sometimes used to separate a heater flue's exhaust gases from a fireplace, esp. when the Fp is located in lower levels of the home.

TSDs are not approved for use on any factory built fireplaces, woodstoves, gas fireplaces, etc.

HTH,
Bob