# Whats the purpose of a damper on a wood stove ?



## Chrism (Apr 2, 2011)

when i install my Isle Royale should i install one ?? i see some stove set ups have them and some dont.


----------



## remkel (Apr 2, 2011)

From what I understand, dampers are installed to help control the draft- sometimes there is just too much, and the damper helps to control that draft. As for should you put one in, well, not kowing anything about the draft in your chimney, chimney height, dimensions etc. I don't believe i could begin to provie you with an opinion on that.


----------



## wingsfan (Apr 2, 2011)

I put one in my wood burner to help with over draft. My stove kept burning hot so I put one in and now I can control the heat better.


----------



## Woody Stover (Apr 2, 2011)

Chrism said:
			
		

> when i install my Isle Royale should i install one ??


I tried to search your previous posts to find out some particulars, but got an error msg. Care to provide some chimney details? Then I can take a wild guess as to weather you might need a damper. It will probably be wrong but I'd enjoy trying nonetheless.
                                      :lol:


----------



## soupy1957 (Apr 2, 2011)

Since the principle behind a "damper" has already been spoken to, I'll not repeat that part.  However, I CAN tell you that I considered one in my flue pipe but didn't install one in the end.

First off, I get good draft to begin with.

Secondly, I find I can control the heat I'm pushing into my house, as opposed to letting it just go "up the chimney" by the "damper" that is built into the stove itself.

That's NOT to say, that with the damper fully open on the stove, I DON'T get heat into the house; certainly the stove does heat the house, regardless...........it's just to say that dampering the flow, helps on more levels than just slowing down the burn.  

But ya'll know that already.

On an older stove, (pre-EPA regulated designs), I hear that a flue damper is more useful.

-Soupy1957


----------



## shawneyboy (Apr 2, 2011)

Chrism,

I am of the believe that it is better to have it and not need it than need it and not have it.   You do need to relize that with any flue damper, even when wide open they will slow your draft up a smidge just because it is an obstruction, ever so minor, in your flue.  My draft is fine and I have not had to use it except by my own making.  It is not "needed" in general with newer stoves but......  for the cost if it has no negetive impact on your draft, it isn't a bad piece of insurance.  This of course is just in my opinion, and please take it with a grain of salt. 

If you can describe the type, length, etc of your flue then perhaps we can be of more help.  

Shawn


----------



## pen (Apr 2, 2011)

I agree with Shawn.  I installed one on my englander and I think I have used it a total of 3 times in 2 years.  The wife has used it a few times when she has gotten things rocking and rolling a bit too much.

pen


----------



## Billy123 (Apr 2, 2011)

Does the damper choke the fire? Would it be better to control the air coming into the air box?

Are there any wood stoves with electronic air control, regululating air for maximium burn and heat?


----------



## pen (Apr 2, 2011)

Some times the terminology gets confused and it makes it difficult to understand.  The damper goes in the stove pipe and the primary air control is what feeds the fire.

On modern stoves, choking the primary air slows the whole system down, at least to a certain point.  The only reason for a damper in the flue pipe is if stove's own air control can't slow things down enough due to excessive draft.  Continued excessive draft can cause an overfire condition.  The flue damper would be installed in this case to help reduce the draft's pull that the stove feels.

With that said, there are some folks who believe that a damper will "hold the heat in the stove."  This is not the case w/ a modern epa appliance.  Instead, using a damper when unnecessary disrupts the balance of air feeding the fire and can make the burn less efficient.  Modern stoves require more draft than their predecessors.

pen


----------



## Woody Stover (Apr 2, 2011)

shawneyboy said:
			
		

> I am of the believe that it is better to have it and not need it than need it and not have it.


I put one in my new liner setup just because I had it. I might need it one day, but don't use it now.



			
				pen said:
			
		

> using a damper when unnecessary disrupts the balance of air feeding the fire and can make the burn less efficient.


Huh. I figured that no matter which end you cut the air flow from, the net result would be the same. 
I always thought that the flue damper wouldn't hold any heat in, since the same amount of air is moving through the stove...


----------



## pen (Apr 2, 2011)

Woody Stover said:
			
		

> I always thought that the flue damper wouldn't hold any heat in, since the same amount of air is moving through the stove...



For example I loaded my stove at 8am this morning.  Right now it's cruising at 575-600 w/ kinda "poofy" if you will secondaries intermixed with bursts of secondary flaming much like a solar flare.  If I were to start closing down the pipe damper the whole stove would slow down, to counteract I would have to open up the primary air.  In opening up the primary air I would be reducing the pull the secondaries feel, they would go out and all I would have is some flames off of the logs in the front of the stove sort of like what my pre-epa stove used to do.

The secondaries are positioned to most effectively burn the wood gasses.  Combustion only in the front of the stove from the primary air coming over the air wash isn't as clean a burn.

pen


----------



## grommal (Apr 2, 2011)

Flue dampers, as previously stated, are installed to mitigate problems with excessive draft.  If you can control your stove without one, then you don't need one.  And if you have one but don't need it, it's just one more thing to disassemble and clean when you're cleaning the pipe.  I'd try it first without.  It's not a difficult retrofit if you have to add one later.


----------



## Woody Stover (Apr 2, 2011)

pen said:
			
		

> Woody Stover said:
> 
> 
> 
> ...


So on the 30, there's no secondary air control? I don't know how that would affect my Keystone; I'm not sure if there's a separate air supply to the combustor or if it just pulls its air off the air wash. Now on the Dutchwest, there's a separate adjustable air inlet for the combustor. I never did figure out if it made much difference...combustor was half shot and I never had dry wood. I may play with it again after I rebuild the stove. And I _will_ have dry wood from here on out.
                                                                                                                                                                               :coolsmile:


----------



## begreen (Apr 2, 2011)

Secondary air controls are rare. You'll find them on the old VC stoves. IIRC, the instructions were to leave it open unless burning in the bypass mode with the damper open.


----------



## snowleopard (Apr 2, 2011)

Some factors to keep in mind as you evaluate the usefulness of my advice:  a) I'm scrupulous about doing a daily (at least) run-up fire, and b) I have prior experience with pre-EPA stoves and pipe dampers, so for me, a stove just seemed all wrong without one.  I had it installed as a just-in-case, and thought I would rarely use it. I use it daily.

Installed it as the first section above the stove so that it would get maximum heat, and get less dirty. 

I leave it open when I'm bringing the stove up to temps (400-500), and then will shut it down judiciously.  Sometimes I'll leave the primary air intake more open, and shut down the damper, and I shut both at bedtime.   It's my belief that more heat comes off the stove that way, and that I can hold a fire longer.  get plenty of secondary burn with it.   Have come down in the night to check on the stove and stayed to watch dancing sheets of blue flame, so I believe it's burning efficiently. 

I have a straight shot pipe and good draft.  I'm not sure it would be a good idea under other circumstances.  It proved itself very useful in a severe windstorm we had a few months ago--40-50 mph winds whipping overhead, flame guttering in the stove from the pull until I shut the damper. 

Also, I believe my Excel damper has more open cut-outs in it than the one in the picture above.


----------



## pen (Apr 2, 2011)

snowleopard said:
			
		

> Some factors to keep in mind as you evaluate the usefulness of my advice:  a) I'm scrupulous about doing a daily (at least) run-up fire, and b) I have prior experience with pre-EPA stoves and pipe dampers, so for me, a stove just seemed all wrong without one.  I had it installed as a just-in-case, and thought I would rarely use it. I use it daily.
> 
> Installed it as the first section above the stove so that it would get maximum heat, and get less dirty.
> 
> ...



As always, you are welcome to do as you wish but the folks who make your stove say that is unnecessary unless you have an overdraft situation.  

Maybe you have an overdraft, because I am amazed you can close the stove down all the way and the pipe all the way at night and not make a creosote factory.

pen


----------



## snowleopard (Apr 2, 2011)

Right you are, Pen, about the manufacturer's recommendation.  I may indeed have an overdraft.  I know that when the stovepipe was installed, before it was sealed off, it pulled in buckets of cold air downstairs.   I've never measured the draft, and don't know if the installers did, but I've never had a problem with insufficent draft.


----------



## pen (Apr 2, 2011)

snowleopard said:
			
		

> Right you are, Pen, about the manufacturer's recommendation.  I may indeed have an overdraft.  I know that when the stovepipe was installed, before it was sealed off, it pulled in buckets of cold air downstairs.   I've never measured the draft, and don't know if the installers did, but I've never had a problem with insufficent draft.



Proof is in the puddin.  If the house is warm and the chimney / cap are staying clean then all is well.  If i remember you have a straight shot up and out?  Many people do not and 2, 90's really puts a drag on a system.

pen


----------



## snowleopard (Apr 2, 2011)

Meant to add that caveat, and did not.  I would probably have done differently if I had offsets and 90s.  I have a straight shot, double-wall from stove to first-floor ceiling, and insulated chimney from there out.  I have two stories, 8' ceilings, attic with a double-batt of insulation in it, and a cold roof.  The ridgeline of my house is about parallel with the ridgeline of the hillside that that I'm sitting on, and the house is on the lee side of that.  My stovepipe is on the lee side of the house, about two or three feet off the ridge beam.  From what I"ve seen hanging out on the forums, it can't get a whole lot more cook-book than that.  

It's never just the stove.


----------



## firefighterjake (Apr 4, 2011)

I think by now most folks have explained what the damper does and how there may be a use for them on stoves that are drafting too quickly . . . I opted to not go with one despite a relatively tall chimney since I figured I could add it later if needed. In three years I have not found a need for one . . . two times I had a fire that was getting a bit worrisome . . . first time I fixed the problem with a fan blowing directly on to the stove . . . second time I fixed it by adjusting the incoming primary air with a piece of tinfoil I had fashioned ahead of time . . . and in both times the main culprit that brought me to the problem of a fire trying to get too hot was the common denominator of me being stupid and putting wood on a fire without letting the normal cycle take place.


----------



## woodchip (Apr 4, 2011)

My thought about chimney dampers is that the primary air supply is where the oxygen for combustion is controlled in newer stoves. 

If you have a damper on the flue, there is always the risk you could leave that shut accidentally when opening the door for reloading. 
Should you do this, Oxygen will go into the firebox from the room, and an increase in combustion within the firebox from the remaining fuel.
Should that take place, where are the smoke and flames going to go, if the chimney is closed off by a damper?

Just considering a worst case scenario.........


----------



## snowleopard (Apr 5, 2011)

woodchip said:
			
		

> My thought about chimney dampers is that the primary air supply is where the oxygen for combustion is controlled in newer stoves.
> 
> If you have a damper on the flue, there is always the risk you could leave that shut accidentally when opening the door for reloading.
> Should you do this, Oxygen will go into the firebox from the room, and an increase in combustion within the firebox from the remaining fuel.
> ...



I haven't had a problem with flames coming out, but my worst case scenario is that smoke starts to come out, in which case I notice that smoke is coming out, shut the door, then open the damper.   It's not a subtle thing.  

Pretty much like people did it in the old days when most folks had dampers in the pipe.  (Note that I said `most people', not BB,  because I didn't want to make him sound old.)


----------



## xjcamaro89 (Apr 5, 2011)

I too have thought about installing a damper in my stove pipe. I have a EPA exempt stove without any intake air control, my chimney is straight up and out, Ive never had a problem with not getting a draft. There is a damper installed in the stove but it can only close about 60%. What i notice is that sometimes i get a powerful draft, so much that the flames look like they are getting sucked towards the back of the stove because the air intake is right above the door and airwashes the glass then moves toward the back of the stove. So when i get some fires like that they are fast and hot. This is my first year burning so im still learning and i pull apart my chimney every month and clean it. I also read on the website where i got my stove from, a review of the stove by another buyer, in that reveiw they stated that they installed a second damper about 15" above the factory one. (The factory one is in the stove pipe adapter on top of the stove) And it gave them more control and longer burns. So im really thinking about putting one in for next year. Any thoughts.


----------



## pen (Apr 5, 2011)

xjcamaro said:
			
		

> I too have thought about installing a damper in my stove pipe. I have a EPA exempt stove without any intake air control, my chimney is straight up and out, Ive never had a problem with not getting a draft. There is a damper installed in the stove but it can only close about 60%. What i notice is that sometimes i get a powerful draft, so much that the flames look like they are getting sucked towards the back of the stove because the air intake is right above the door and airwashes the glass then moves toward the back of the stove. So when i get some fires like that they are fast and hot. This is my first year burning so im still learning and i pull apart my chimney every month and clean it. I also read on the website where i got my stove from, a review of the stove by another buyer, in that reveiw they stated that they installed a second damper about 15" above the factory one. (The factory one is in the stove pipe adapter on top of the stove) And it gave them more control and longer burns. So im really thinking about putting one in for next year. Any thoughts.



Becareful doing that.  Since your stove does not have the secondary air system or a catalyst, if you damper that down too much you will have a creosote manufacturing device hooked to your chimney.

pen


----------



## Woody Stover (Apr 5, 2011)

As I said, I wasn't using my damper but today it occurred to me that I can use it early in the burn after the load has caught, when I open the door to hear if the wood is still hissing. Instead of trying to listen through the roar, I can close the damper a bit and hear better. Once I'm burning well-seasoned wood I shouldn't need it...


----------



## oldspark (Apr 5, 2011)

pen said:
			
		

> xjcamaro said:
> 
> 
> 
> ...


 If he monitors his flue temps he should be OK, you could put 10 dampers on there as long as the flue temp stayed in the correct range.


----------



## moosetrek (Apr 5, 2011)

I also added one when I installed the PE, and since I live in a wind-prone area where 40-50 mph winds are common, I find it helps control the draft.  Like Snowleopard, I have double wall to the ceiling, and a straight shot up through the roof so that may be a factor.  If I lived in a less windy place, I might rethink but it really makes a difference in my setup.


----------

