Manual Pipe Dampers - A Matter of Perspective

 
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tcalo
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Post by tcalo » Sun. Dec. 15, 2013 5:08 pm

Lightning wrote:Close the manual which lowers the pressure which means less volume thru the combustion air controls. :D

Limit air in by limiting air out...
Does this mean the combustion air would decrease with the MPD closed, even with the air setting wide open? Technically it should...right?


 
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Post by Lightning » Sun. Dec. 15, 2013 6:03 pm

tcalo wrote:
Lightning wrote:Close the manual which lowers the pressure which means less volume thru the combustion air controls. :D

Limit air in by limiting air out...
Does this mean the combustion air would decrease with the MPD closed, even with the air setting wide open? Technically it should...right?
Yes, provided the air setting was wide open when the MPD was open.. Less negative pressure in the fire box means less combustion air entering the stove..

 
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Post by Lightning » Sun. Dec. 15, 2013 6:08 pm

Keepaeyeonit wrote:I would think that the air though the fire bed would decrease due in part to the exhaust being slowed or limited by the mpd.I may be wrong but I think its another tool to help control the burn but It requirers user input. Thats my perspective on them and like I said I'm not 100% sure because I never used one(I use a baro),so if I'm wrong someone set me straight :oops: .Keepaeyeonit
I agree since air in is being limited by air out, and also agree that a baro has the same effect by weakening the negative pressure in the fire box. :D

 
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Post by rberq » Sun. Dec. 15, 2013 6:40 pm

Lightning wrote: air in is being limited by air out
That's kind of half true. Under normal circumstances more gas volume goes out than comes in. Disconnect your stovepipe from the stove (please don't, really :D ) and the firebox will create its own draft, just like the can-style charcoal starter used for your barbeque. The stove will keep right on burning happily without a chimney as long as you keep the ashes clear. Chimney draft does two things: (1) provides adequate suction to remove products of combustion; and (2) if draft is more than "adequate", extra air is sucked into the stove to make the fire burn faster. Dampers of either type, MPD or baro, just reduce the influence of the chimney. It's OK if you reduce function (2) but it's deadly if you reduce function (1) too much. :cry:

 
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Post by Lightning » Sun. Dec. 15, 2013 7:54 pm

I agree with all of that except the first sentence. :) if air can't get out, it can't get in. I believe the change in volume would only be due to the gases going out would be hotter and lighter thus taking up more space for their mass which is why they rise. .. :D

Hypothetically I believe you could extinguish a fire in the stove by completely blocking the flue even if the ash pan door were wide open, provided the rest of the stove sealed well.

 
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Post by rberq » Sun. Dec. 15, 2013 9:50 pm

Lightning wrote:I believe the change in volume would only be due to the gases going out would be hotter and lighter thus taking up more space for their mass which is why they rise.
My bad. :cry: You are right. My thinking was that the molecules of carbon dioxide going out the flue (CO2) are heavier and therefore have more volume than the oxygen coming into the stove (O2). It is true that each molecule is heavier, but the gas volume is the same. (Except in the case of incomplete combustion, where each O2 molecule becomes two carbon monoxide (CO) molecules and the volume increases.)

Been a long time since high school chemistry, and it was counter-intuitive even then. :P

http://www.gutenberg.org/files/22657/22657-h/chap ... uegas.html

 
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Post by Lightning » Mon. Dec. 16, 2013 2:18 am

Wow, thanks for posting that link..
Some cool information in there 8-) :ugeek: :D


 
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Post by dustyashpan » Sat. Dec. 21, 2013 12:58 pm

KLook wrote:NO thoughts......it is just as I would expect. 8-) The baro is the way to go.

Kevin
problem. baro is oil burner boiler device, retrofitted to coal. when opened pulled cold basement cellar air up chimney. when designed cellars were not finished, many had dirt floor, stone foundation. no heat there to really lose. today baro in heated living room, basement finished den, pulls heated room air up chimney, wastes more heat than is saves.

 
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Post by Lightning » Sat. Dec. 21, 2013 3:32 pm

dustyashpan wrote:
KLook wrote:NO thoughts......it is just as I would expect. 8-) The baro is the way to go.

Kevin
problem. baro is oil burner boiler device, retrofitted to coal. when opened pulled cold basement cellar air up chimney. when designed cellars were not finished, many had dirt floor, stone foundation. no heat there to really lose. today baro in heated living room, basement finished den, pulls heated room air up chimney, wastes more heat than is saves.
We went over all this nonsense in another thread. Barometric dampers do not waste more than they save.

Good luck telling the hundreds of people on here that use a barometric in their living room for years that they've been doing it all wrong :lol:

Usually the people that are dead set against a barometric haven't used one to see how beneficial it is to maintain a steady draft pressure.

Just for the record, Field Controls manufacturers a barometric damper specifically for oil and coal. :D

 
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Post by kirtsy420 » Mon. Jan. 20, 2020 2:49 pm

everytime my baro opens it never closes. cools my stove down almost 200 degrees in 35 mins. im going to install a mpd today after work and see what i come up with. from what ive been understanding dustyashpan is right to an extent. if your stove is in a finished room or finished basement a baro works great. but if the stove is in an unfinished room it does not work properly. my kodiak stove has been eating the coal. yesterday when the temps were degrees i went through a bag in a half almost 2 bags. my pipe runs about 275 300 when ive got the ash pan door open when im adding coal. couple of the local amish guys told me to install a mpd so i dont let so much heat out. they said pipe should be 150 to 200 degrees. dont know if it will work or not but a mpd was only 4 bucks so im gonna try it.

 
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Post by coaledsweat » Mon. Jan. 20, 2020 3:09 pm

Did you check to see if the baro flapper is binding? It should swing freely at all points.

 
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Post by kirtsy420 » Mon. Jan. 20, 2020 3:56 pm

sure have. doesnt have a problem opening just closing it wont do. also my basement is not finished either.

 
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Post by rberq » Mon. Jan. 20, 2020 6:28 pm

kirtsy420 wrote:
Mon. Jan. 20, 2020 2:49 pm
everytime my baro opens it never closes.
Could you post a picture or two of the baro??? My oil burner baro acted like that, and it turned out there was a weight that had fallen (rusted) off. I hate to see someone abandon the convenience of a baro if it's not necessary. :cry:

 
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Post by coalder » Mon. Jan. 20, 2020 6:52 pm

It would be extremely interesting, to see if there were scientific a way to determine the volume of heated air, in a given area that a baro exhausted as opposed the the effects of an MPD. And in today's modern building practices, of a tight house, which device would be the most appropriate. Not looking for opinions or arguments. Just saying, a plausible explanation of fact has to exist somewhere.
Jim

 
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Post by scalabro » Mon. Jan. 20, 2020 6:55 pm

coalder wrote:
Mon. Jan. 20, 2020 6:52 pm
It would be extremely interesting, to see if there were scientific a way to determine the volume of heated air, in a given area that a baro exhausted as opposed the the effects of an MPD. And in today's modern building practices, of a tight house, which device would be the most appropriate. Not looking for opinions or arguments. Just saying, a plausible explanation of fact has to exist somewhere.
Jim
You’d better get busy Jim!


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