Damper Do's And Dont's

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BillBurns

New Member
Nov 11, 2022
92
PA
I was just wondering what everyone does with their damper? I leave mine open til the thermometer reads in the prime temps. Then I close it half way down. Is that good or should I close it the whole way once its down to coals?
 

Eman85

Member
Oct 10, 2022
211
E TN
When you say damper which do you mean a damper in the flue pipe a damper for the redirection of smoke for a catalyst or do you mean the intake air control?
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,392
South Puget Sound, WA
Yes, this needs clarification. Some call the primary air control the damper. Some stoves have a bypass damper. Others may have a stove pipe (key) damper. And some have all three!
 

BillBurns

New Member
Nov 11, 2022
92
PA
My damper is about 15 inches from the stove. Mine is a non cat. Im just not sure if im doing it quite right? Oh. its on the flue.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,392
South Puget Sound, WA
The operation of the flue damper depends on the stove and how strong the draft is. One might close it down only 50% when it's 40º outside and 100% when it's 20º. Closing it down all the way still allows the passage of about 25% of the flue gases. This is by design.

As for the timing. That sounds about right for a cold start. On a reload over hot coals it may only be necessary to open the flue damper for the reload, then closing it down again after the reload ignites. This is more of a visual thing for me. If closing it down causes the fire to get too anemic or smolder then it's restricting too much.
 

BillBurns

New Member
Nov 11, 2022
92
PA
Thanks for the advice! I never closed it the whole way, cause I thought about the gases backing up into the house, but dampers do have small holes in them. Thanks again.
 

Highbeam

Minister of Fire
Dec 28, 2006
20,013
Mt. Rainier Foothills, WA
Even a fully open key damper is a restriction in the flue. The goal is to reduce draft strength to a certain level that your stove runs efficiently at. The natural draft varies with temperature and wind so your damper settings will change as well. This is the biggest reason barometric dampers were invented, to automatically deliver that desired draft to the appliance.
 

blades

Minister of Fire
Nov 23, 2008
3,784
WI, Leroy
baro dampers by design lead to other issues as well. they are great for gas units and maybe coal, but with wood as fuel source the issue of cooling the flue invites creosote formation.
 

Highbeam

Minister of Fire
Dec 28, 2006
20,013
Mt. Rainier Foothills, WA
baro dampers by design lead to other issues as well. they are great for gas units and maybe coal, but with wood as fuel source the issue of cooling the flue invites creosote formation.
You might think so but wood furnace manufacturers specify their use and even have included the baro dampers with new stoves.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,240
central pa
You might think so but wood furnace manufacturers specify their use and even have included the baro dampers with new stoves.
Yes and they still cause problems
 

Highbeam

Minister of Fire
Dec 28, 2006
20,013
Mt. Rainier Foothills, WA
Yes and they still cause problems
Since only two are legal for sale have you seen baro damper problems above these two? The kuuma and drolet. They claim the furnaces are so clean that it’s not a problem but we know how that goes.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,240
central pa
Since only two are legal for sale have you seen baro damper problems above these two? The kuuma and drolet. They claim the furnaces are so clean that it’s not a problem but we know how that goes.
Not the new 2020 compliant ones no.
 

rudysmallfry

Minister of Fire
Nov 29, 2005
558
Milford, CT
If you do damper down before the secondary combustion stage, make sure you keep it open enough that the pipe stays up to a proper temperature. If you turn it down too much and cool down your chimney too much, that's when creosote will quickly start to collect. I have an older stove and do have to damper down on the very cold nights where the fire would otherwise take off, but have noticed going too far closed does result in more build up.

On my stove, I've found I can get the stove to hold more heat by manipulating the damper and the air together. Instead of turning down just one or the other, I'll take both down a 1/4 and let it go for awhile before doing another 1/4 turn down. Usually after the damper is 1/2 closed, I just turn down air after that until that is cut to it's minimum. Every stove is different, so just play with it until you get the desired affect.
 
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