Woodstove Chimney Dampers

[Rob Crosby]

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Wood Stove Chimney Dampers
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We live in Maine and have a wood stove in a great room. It draws air from under the floor in a crawl space with vents to the outside. A single wall chimney extends about 16 feet to the ceiling peak. When we aren't burning wood the damper is closed at the fireplace level but it seems that we still lose a lot of heat as cold air enters the pipe from above. Is there a damper system that could be installed at the ceiling level to minimize this heat loss?
Any suggestions or comments greatly appreciated. I've argued with my wife that the single, floor level damper basically turns the chimney into a dead air chamber and that heat loss shouldn't be that great. She feel differently and since she has an habit of being right about these things I wouldn't be surprised if she were right about this too.
Thanks,
Rob

 

[smokedragon]

If you really want a damper at the ceiling level, read these websites. They have different options of dampers. Some go at the top of your pipe, some go in at your woodstove exit (chimney pillow).

http://www.chimneydampers.com/

http://www.volkosupply.com/products.cfm?category_id=19&subcategory_id=26&id=19&thiscat=19

(broken link removed to http://www.rockfordchimneysupply.com/pic.php?pic=round-damper.jpg&cap=Round_Stainless_Steel_Chimney_Damper_Kit)

(broken link removed to http://www.rockfordchimneysupply.com/pic.php?pic=ChimneyBalloonlg.jpg&cap=Chimney_Balloon)

Have you considered that you may be getting a draft from the fresh air inlet as well?

Also consider when it is really cold outside, it may not be a draft but conduction......you have a metal stove and a metal pipe. They will conduct heat from a hot place to a cold place. Your stove and pipe could be conducting heat up through your ceiling. There is no cure for this except to burn the stove.

 

[coaly]

Your theory that the closed damper doesn't allow colder air to drop down the pipe depends on the damper. None seal tight to create a dead air space when closed. They all have holes along the center shaft. Older dampers have larger center holes to allow an overnight burn fully closed. The larger the damper, the larger the opening.
Different dampers; With controlled flow when closed.



I stuff rags in a plastic bag and plug it while not in operation. Keep it open during summer since cool night moisture laden air drops in, and during the day as it warms up the air rises leaving the moisture behind.

 

[smokedragon]

Your theory that the closed damper doesn't allow colder air to drop down the pipe depends on the damper. None seal tight to create a dead air space when closed. They all have holes along the center shaft. Older dampers have larger center holes to allow an overnight burn fully closed. The larger the damper, the larger the opening.
Different dampers; With controlled flow when closed.

View attachment 129035 View attachment 129036

I stuff rags in a plastic bag and plug it while not in operation. Keep it open during summer since cool night moisture laden air drops in, and during the day as it warms up the air rises leaving the moisture behind.

Look at the dampers that are in the links I posted. They are not key dampers, but flue dampers. Two different contraptions. Flue dampers do in fact seal the chimney shut (the new ones have fancy silicone gaskets).