butterfly dampers
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Eric Johnson
Mod Emeritus
If you mean a standard cast-iron stove-pipe damper, then any decent hardware store or stove supply place. I think they cost about $7.
Eric Johnson
Mod Emeritus
^^^^You're probably right. I was thinking about an industrial butterfly valve, which works like a standard damper. I've never heard either one referred to as a "butterfly" damper. You'd get a barometric damper at any plumbing/heating supply house.
henfruit
Minister of Fire
henfruit
Minister of Fire
totally different animals-
The butterfly damper is indeed the old stove type damper- and really poses some hazards. I know, because I used to have one on my old wood/ hot air furnace, and once, after setting it all up nice and sweetly for a perfect hot but gradual burn before going to bed, a weather pattern shifted and a thermal inversion came through the area. Woke up to a foggy head, screaming headache, and a house that was like a smokehouse. I do not recommend them with any modern appliance designed and made after about 1908.
Barometric dampers are a whole different critter. They self-regulate the draft so that it does not exceed a certain preset amount, and do so by feeding in excess air between the appliance and chimney. Properly installed, and with an appliance that they are safe with (which includes modern gasifiers but does not include low efficiency units that can accumulate combustibles in the flue pipe) they are pretty safe. Poorly installed, or with an unsuitable combustion appliance, they, too, risk belching smoke back out of the weighted damper, or feeding oxygen to a chimney fire (note- they will not _cause_ a chimney fire).
The butterfly damper is indeed the old stove type damper- and really poses some hazards. I know, because I used to have one on my old wood/ hot air furnace, and once, after setting it all up nice and sweetly for a perfect hot but gradual burn before going to bed, a weather pattern shifted and a thermal inversion came through the area. Woke up to a foggy head, screaming headache, and a house that was like a smokehouse. I do not recommend them with any modern appliance designed and made after about 1908.
Barometric dampers are a whole different critter. They self-regulate the draft so that it does not exceed a certain preset amount, and do so by feeding in excess air between the appliance and chimney. Properly installed, and with an appliance that they are safe with (which includes modern gasifiers but does not include low efficiency units that can accumulate combustibles in the flue pipe) they are pretty safe. Poorly installed, or with an unsuitable combustion appliance, they, too, risk belching smoke back out of the weighted damper, or feeding oxygen to a chimney fire (note- they will not _cause_ a chimney fire).
LeonMSPT
Minister of Fire
You mean on of these, hanging off the back of my New Yorker wood/coal boiler?
1. Have to clean the connector pipes, about every three weeks to a month, depending on how much back and forth I do from wood to coal. Burning coal, I'd have to clean it once a month anyway to rid it of fly ash. Piped up the way it is, I take three screws out of the two end caps, run a 6 inch brush in and out of the horizontals a few times, hand brush the T with the damper cut into it, pop the caps back in and put the screws back. I got about ten minutes from start to finish in it each time. Well worth the time.
2. I've never had smoke come back out of it. I take it back... when I lit it last night, wind gusts approaching 45 miles an hour, cold start... one little small puff about three minutes into the burn. I think it needed to break the thermal and a gust happened to blow just right. Other than that I have no smell, no problems... draft at six inches behind boiler is about .025 inches... without the barometric damper it is .23 inches...
3. "If" you have a chimney fire, it will feed air to it. Properly maintained, cleaned, adjusted, and used, it's not likely to be a problem. Without the barometric damper, I was burning wood in a vacuum. On high fire the pipe temperatures were hot enough that the galvanized pipe it was hooked to turned grey and stunk. Stick on thermometer read as high as 650 degrees on a couple occasions. The boiler too longer to come up to temperature, and was belching nasty smoke out the chimney the entire time it was burning, including at idle. With the damper, the stack temps never exceed 425 degrees... at the highest. The door climbs as high as 575 degrees.
4. The operative word in #3 was "If". Without the barometric damper, it was only a matter of "when". There was no question with the low stack velocity and heavy particulates accumulating on the flu, as well as the average load.
5. Give a fool almost any tool, and he'll find a way to hurt himself with it. Allow any dummy to burn wood, no matter the device, and he'll find a way to burn his house down with it.
6. I'd use a barometric damper on the boiler even if I burned wood full time. Maintenance? Yes. That's the nature of burning wood anyway. Anybody afraid of taking care of things shouldn't be burning wood. It's not for them.
7. Burn safely, it's the only way. It takes longer and costs more to do it any other way.
1. Have to clean the connector pipes, about every three weeks to a month, depending on how much back and forth I do from wood to coal. Burning coal, I'd have to clean it once a month anyway to rid it of fly ash. Piped up the way it is, I take three screws out of the two end caps, run a 6 inch brush in and out of the horizontals a few times, hand brush the T with the damper cut into it, pop the caps back in and put the screws back. I got about ten minutes from start to finish in it each time. Well worth the time.
2. I've never had smoke come back out of it. I take it back... when I lit it last night, wind gusts approaching 45 miles an hour, cold start... one little small puff about three minutes into the burn. I think it needed to break the thermal and a gust happened to blow just right. Other than that I have no smell, no problems... draft at six inches behind boiler is about .025 inches... without the barometric damper it is .23 inches...
3. "If" you have a chimney fire, it will feed air to it. Properly maintained, cleaned, adjusted, and used, it's not likely to be a problem. Without the barometric damper, I was burning wood in a vacuum. On high fire the pipe temperatures were hot enough that the galvanized pipe it was hooked to turned grey and stunk. Stick on thermometer read as high as 650 degrees on a couple occasions. The boiler too longer to come up to temperature, and was belching nasty smoke out the chimney the entire time it was burning, including at idle. With the damper, the stack temps never exceed 425 degrees... at the highest. The door climbs as high as 575 degrees.
4. The operative word in #3 was "If". Without the barometric damper, it was only a matter of "when". There was no question with the low stack velocity and heavy particulates accumulating on the flu, as well as the average load.
5. Give a fool almost any tool, and he'll find a way to hurt himself with it. Allow any dummy to burn wood, no matter the device, and he'll find a way to burn his house down with it.
6. I'd use a barometric damper on the boiler even if I burned wood full time. Maintenance? Yes. That's the nature of burning wood anyway. Anybody afraid of taking care of things shouldn't be burning wood. It's not for them.
7. Burn safely, it's the only way. It takes longer and costs more to do it any other way.
pybyr said:
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Leon-
I've usually been the one 'round these parts to point out that there is a good reason for a barometric damper on a modern (gasifer, etc.) wood burning appliance -even though lots of other folks are hesitant about it based on some widespread folklore that one should supposedly not use a barometric damper on any solid fuel appliance.
So if that (My OK-ness with a barometric damper) is not clear, I hope that I just made it clear.
I use one.
Out of general curiosity about burning parameters, I also watch a good draft gauge, which confirms that I'd be getting a less consistent, less efficient, burn without the B.D.
Did I clarify myself?
I've usually been the one 'round these parts to point out that there is a good reason for a barometric damper on a modern (gasifer, etc.) wood burning appliance -even though lots of other folks are hesitant about it based on some widespread folklore that one should supposedly not use a barometric damper on any solid fuel appliance.
So if that (My OK-ness with a barometric damper) is not clear, I hope that I just made it clear.
I use one.
Out of general curiosity about burning parameters, I also watch a good draft gauge, which confirms that I'd be getting a less consistent, less efficient, burn without the B.D.
Did I clarify myself?
LeonMSPT
Minister of Fire
I like you. 
Particularly nasty burning old-style boilers and owners can benefit from them too. But nobody ever said burning wood was easy, or "safer" than oil, gas, or electric... if it was, everybody would still be doing it. It is dirty, work, inconvenient at times, and if done improperly in even sometimes the slightest way you can get killed or bunr down your house.
I am in the process of procuring one of the Dwyer units to live permanently on the chimney just outside of the clearance of the pipe system. I want to be able to see what is going on, all the time... not just the day I set the thing up.
My K-factor for the month between 12/19 and 1/14 was nearer to the rate from last May to September period, than it was to last year at the same time... burned 50 gallons of #2 and some wood/coal in the boiler, and some wood in the airtight insert.
I didn't want to put the barometric damper in... the signs and writing on the wall in front of me said, "You'd better."
Particularly nasty burning old-style boilers and owners can benefit from them too. But nobody ever said burning wood was easy, or "safer" than oil, gas, or electric... if it was, everybody would still be doing it. It is dirty, work, inconvenient at times, and if done improperly in even sometimes the slightest way you can get killed or bunr down your house. I am in the process of procuring one of the Dwyer units to live permanently on the chimney just outside of the clearance of the pipe system. I want to be able to see what is going on, all the time... not just the day I set the thing up.
My K-factor for the month between 12/19 and 1/14 was nearer to the rate from last May to September period, than it was to last year at the same time... burned 50 gallons of #2 and some wood/coal in the boiler, and some wood in the airtight insert.
I didn't want to put the barometric damper in... the signs and writing on the wall in front of me said, "You'd better."
pybyr said:
LeonMSPT
Minister of Fire
On the issue of smoke backing out of the damper...
Mine is a 7 inch damper, cut into a 6 inch radiused T. I went with the 7 inch because of the FC website instructions that said, "Big chimney = big barometric damper". They said that if the chimney is higher than 15 ft, use a 7 or 8 inch damper. It will help to relieve "more" than a 6 inch damper.
I think the flip side might also be true. Got a shorter chimney with a larger flu? Maybe using a size down from the chimney connector pipe might be a good idea? It will still allow you to set the force of the draft, as the chimney hasn't got the pulling power of the 35 foot tall, 6.5 x 6.5 inch "stack" hooked to my wood boiler. However, there is less "space" available for the smoke and air to exit in a smaller damper. More resistance to it.
Some of them likely don't even need one, chimney's draft is marginal in the first place, and a barometric damper would belch smoke and remain closed most of the time anyway?
Lots of variables and few certainties, except if it's not done right it can rear up and bite you anytime. Might be the first day, and it might be 20 years down the road. But rest assured it's always there, if it's not right.
Mine is a 7 inch damper, cut into a 6 inch radiused T. I went with the 7 inch because of the FC website instructions that said, "Big chimney = big barometric damper". They said that if the chimney is higher than 15 ft, use a 7 or 8 inch damper. It will help to relieve "more" than a 6 inch damper.
I think the flip side might also be true. Got a shorter chimney with a larger flu? Maybe using a size down from the chimney connector pipe might be a good idea? It will still allow you to set the force of the draft, as the chimney hasn't got the pulling power of the 35 foot tall, 6.5 x 6.5 inch "stack" hooked to my wood boiler. However, there is less "space" available for the smoke and air to exit in a smaller damper. More resistance to it.
Some of them likely don't even need one, chimney's draft is marginal in the first place, and a barometric damper would belch smoke and remain closed most of the time anyway?
Lots of variables and few certainties, except if it's not done right it can rear up and bite you anytime. Might be the first day, and it might be 20 years down the road. But rest assured it's always there, if it's not right.
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