Why should I buy or not buy a pipe damper?

[Ratman]

Why should I buy or not buy a pipe damper?

Some of you have seen my old cast iron '80s relic with both primary & secondary (door) air flow controls.
Basic 6" single wall back exit elbow staight up setup.
If I can accurately control the infeed then I would think it's more of a hazard than anything; and yes I know it will help the chimney fire scenerio.
I've heard with it you'll burn less wood but create more creosote.
I put this in the hands of the woodstove pro's as to which way I'll go.

 

[Rich L]

I use a pipe damper on one of my stoves which has a very good draft.The stove doesn't shut down enough to keep the wood from burning up too quickly.With the damper I'm able to Keep the flame down and get more heat for a longer time.

 

[edthedawg]

+1 - get it, use it wisely, you'll reduce the chance for problems.

 

[Dune]

With a truly airtight stove you shouldn't need a damper.

With your stove, you need a damper.

 

[Planeweird]

Dune,

How would you define a truly airtight stove?

 

[karri0n]

When you need a damper:

You have a tall chimney with lots of draft, and it makes it difficult to have a controlled fire or impossible to have an overnight burn. This was my scenario before I put one in. I couldn't go more than 5 hours and have enough coals to re-start with the air turned all the way down. Now I can load it up before bed and have a stove full of hot coals when I wake up in the morning 8-9 hours later. If you have excessively high pipe temps more than 18" above the stove, this is a sign that your draft may bee too strong and a damper could help. If your stove is running fairly optimal and you just want a bit more control or to fine tune your burn, this could be an OK situation for a damper also.

When you do not:

You sometimes have too little draft, slow starts, or if the setup is running optimally, has a fairly low stack temp, and can maintain an overnight burn. Sometimes, "if it aint broke don't fix it" is a good motto. If you already have draft or creosote issues, putting a damper may make the situation worse as even a fully open damper will slow the passage of exhaust gases.


I don't know what your stove is, but if you have controls for both secondary and primary air, and you are able to completely snuff out the flames by turning the air down all the way, then your stove very well be *more* airtight than ours. An EPA stove will never be airtight unless the secondary air intake is modified illegally.

It's probably best to assess your situation to see which of these scenarios you fit in with, and make your decision based on that.

 

[Highbeam]

With a truly airtight stove you shouldn't need a damper.

With your stove, you need a damper.

True but you can't buy an EPA non-cat stove that is even remotely airtight anymore. What you now have is a somewhat controllable primary air intake plus a 100% full throttle secondary air inlet (most stoves) pouring combustion air in as fast as the fire wants it. Ever heard of a runaway stove?

I just ordered a damper for my pretty much ideal vertical 14' chimney. Reason is that when the fire is hot and a fresh load of fuel is added for the overnight burn, I lose the ability to stop the stove from raging. It hasn't overfired yet but when you see the needle moving closer to the max temp and there isn't a thing you can do to slow down the raging fire it makes you awfully nervous.

I bought the damper along with a flue thermometer to be sure that when I do damp the flue down that I do send enough heat up the stack to prevent creosote.

 

[cmonSTART]

Obviously there's a lot of debate over this issue. My position is install one if you have an older stove or have a serious problem with overdrafting (very rare). Otherwise they degrade draft and just provide another place for soot to collect and clog things up. The safety benefits are minimal because a pipe damper doesn't shut off air completely. Chances are your air control on your stove will do more to stop or slow airflow in the system than will this damper.

 

[begreen]

If you're burning good dry wood and not letting it smolder, then the pipe damper should be ok. We had one on the 602 and used it for years without any creosote buildup.

 

[Planeweird]

Do you think a Jotul F3 CB with an interior insulated 30' chimney would need one?

 

[wendell]

It is possible. I have 32 ft. and am adding one this year. As someone much wiser here as said, my stove was like a seagull drafting an aircraft carrier. :lol: (to paraphrase)

 

[fbelec]

When you need a damper:

You have a tall chimney with lots of draft, and it makes it difficult to have a controlled fire or impossible to have an overnight burn. This was my scenario before I put one in. I couldn't go more than 5 hours and have enough coals to re-start with the air turned all the way down. Now I can load it up before bed and have a stove full of hot coals when I wake up in the morning 8-9 hours later. If you have excessively high pipe temps more than 18" above the stove, this is a sign that your draft may bee too strong and a damper could help. If your stove is running fairly optimal and you just want a bit more control or to fine tune your burn, this could be an OK situation for a damper also.

When you do not:

You sometimes have too little draft, slow starts, or if the setup is running optimally, has a fairly low stack temp, and can maintain an overnight burn. Sometimes, "if it aint broke don't fix it" is a good motto. If you already have draft or creosote issues, putting a damper may make the situation worse as even a fully open damper will slow the passage of exhaust gases.


I don't know what your stove is, but if you have controls for both secondary and primary air, and you are able to completely snuff out the flames by turning the air down all the way, then your stove very well be *more* airtight than ours. An EPA stove will never be airtight unless the secondary air intake is modified illegally.

It's probably best to assess your situation to see which of these scenarios you fit in with, and make your decision based on that.

how tall does a chimney have to be, to be considered tall and may over draft? i've been thinking about this also. my second stove is running in the basement. it's run into a 7 x 7 masonry chimney thru the middle of the house (a ranch) with a 8 foot tall attic and ends 3 feet about the ridge. that stove could be stone cold (it's soapstone) and i still have a draft when it's teens outside. even if the primary air is closed it still run's on the hot side. i rebuilt this stove not long ago and it seems to me that the only place air is getting in is the secondary air tube.

 

[begreen]

Do you think a Jotul F3 CB with an interior insulated 30' chimney would need one?

The F3CB was installed where the 602 was, so we continued to use the damper. The F3CB needed it less as a regulator, so we mainly used it as secondary combustion was dying down. But with a 30' flue, you may find yourself using it a lot more. If the stove only runs hot and doesn't respond well to complete reduction of the incoming air, I would try a flue damper. It could be that you just run the stove with the flue damper in a fixed position, like half closed and find that to be a good setting. This will take some experimentation.

 

[fbelec]

i should also add that the draft is so good that when i need to start this stove from cold, i rake the ashes into the ash pan keeping the klunkers or charcoal left from the last fire, run them up into a pile and take a propane torch to the pile for about 30 seconds to a minute close the door and open the ash door and in a matter of 2 3 minutes i got a screamin bed of coals to light a fire with.

 

[Dune]

Dune,

How would you define a truly airtight stove?

I define airtight as ;when you shut the air inlet completely, the fire goes out.

 

[Dune]

With a truly airtight stove you shouldn't need a damper.

With your stove, you need a damper.

True but you can't buy an EPA non-cat stove that is even remotely airtight anymore. What you now have is a somewhat controllable primary air intake plus a 100% full throttle secondary air inlet (most stoves) pouring combustion air in as fast as the fire wants it. Ever heard of a runaway stove?

I just ordered a damper for my pretty much ideal vertical 14' chimney. Reason is that when the fire is hot and a fresh load of fuel is added for the overnight burn, I lose the ability to stop the stove from raging. It hasn't overfired yet but when you see the needle moving closer to the max temp and there isn't a thing you can do to slow down the raging fire it makes you awfully nervous.

I bought the damper along with a flue thermometer to be sure that when I do damp the flue down that I do send enough heat up the stack to prevent creosote.

Have you seen Ratmans stove? It is a 1973 cast iron somewhat preEPA. I am pretty sure he needs a damper.

 

[Highbeam]

Point is that air tight stoves were only made for a brief period in history. Since 1991 for sure, there are no more air tight stoves so when the draft adjustment doesn't allow you sufficient control of your stove then you have no choice but to install a damper. Really old stoves only had a flue damper to slow the fire.

This, from fbelec :

"even if the primary air is closed it still run’s on the hot side."

describes the problem. Search for the florida bungalow syndrome. If your installation meets the minimum chimney height requirements in your manual and you do NOT live in Florida then your stove has more draft than it needs and perhaps could benefit from a damper. You can always take it out if you don't like it. I'm trying one to see if I like it.

 

[fbelec]

i've got a damper just didn't install it and wondered everytime i walked by it. the only reason i never installed it was that when i was talking to jim casavant at hearthstone he said to me "nice stove, but you do realize you won't get a over night burn from it." so i figured 3 to 5 hours was the norm for the stove and if it did start to run away i could always slide the cover over the secondary inlet to cool it down. after some of the things said here i'm going to install the damper and see what happens.
i always seem to forget the simple things. like you said highbeam if i don't like it, i'll pull it out.

 

[Dune]

Yeah, my 1978 or thereabouts tempwood is pretty darn airtight, and I don't use a damper, nor miss one, but the 120 year old parlor stove that it repalced sure needed one.

 

[Planeweird]

With the way my stove will be set up, the only realistic place to insert a pipe damper will be in the tee directly off the flue collar. Do you guys see any issue with this location?

 

[Dune]

When I run a damper in a stove, I like to put it as far away from the stove as possible, because the stove pipe throws a lot of heat that way. Others here may have objections to that or better ideas, but that is how I've always done it.

 

[karri0n]

With the way my stove will be set up, the only realistic place to insert a pipe damper will be in the tee directly off the flue collar. Do you guys see any issue with this location?

That's where I've got mine. It's right on top of the flue collar. I had a bit of issue with the heat making the spring tension too low for it to stay in place and it would swing open, so I added a lock washer between the spring and pipe and now it holds just fine. In this position, it's the highest amount of heat on the damper as you are going to get short of drilling through the stove collar(don't do this please), so collecting creosote on the damper is more or less a non issue as long as you are burning properly.

 

[Planeweird]

With the way my stove will be set up, the only realistic place to insert a pipe damper will be in the tee directly off the flue collar. Do you guys see any issue with this location?

That's where I've got mine. It's right on top of the flue collar. I had a bit of issue with the heat making the spring tension too low for it to stay in place and it would swing open, so I added a lock washer between the spring and pipe and now it holds just fine. In this position, it's the highest amount of heat on the damper as you are going to get short of drilling through the stove collar(don't do this please), so collecting creosote on the damper is more or less a non issue as long as you are burning properly.

Good info thank you. I'll have to put mine close because my stove will be right in the opening of a fireplace and all of my pipe will be inside an existing masonry chimney.

 

[Planeweird]

theoretically speaking= assume stove is airtight & chimni still pulls draft, which it does. heat from stove will create an up & down flow of air within chimni which results in a downdraft of air to feed the stove outside air from the top of the chimni,eh?

That doesn't seem logical

 

[Ratman]

I want to thank all of you for assisting me in my decision on whether to purchase and install a flue pipe damper.
We have a great team here and thanks to Mike for founding this site way back when.

So I guess I will purchase and install the damper but mainly for the control it will offer me when I am in the room with the door open and screen on.
I will have to try and find a 5" damper because although I would love to install it in the 6" expander section just below the metalbestos pipe, the screws will be in the way I believe. I'll have to get a 5" and install it around where the flue thermometer is.
I believe the damper will also help me control the stove a bit with the door closed even though it is a 1983 airtight stove so to speak.

Again, thanks so much for all your time and effort folks!
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