iDRY Vacuum Kilns

Sponsors:

Chimney pipe lngth eficiency

Started by Logging logginglogging, December 15, 2012, 08:19:02 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Logging logginglogging

I just saw a video where a guy was saying that eficency could / should be increased by more lengths of chimney. Any truth in this?  I have the stardard 2 lengths of pipe on my stve. I have no neighbors and have never had any problems with smoke. So i have never even thought about mor pipe. Even if it doese increase eficiency, I am hapy with the eficency I have now and dont plan to extend it for two reasons. Looks, and I would think that mor pipe means i would need to support it some how.

WH_Conley

All I ever heard was enough pipe to get it above the the ridge of the roof. This was to eliminate down draft when the wind blew the wrong direction.
Bill

Jack72

Quote from: Logginglogginglogging on December 15, 2012, 08:19:02 PM
I just saw a video where a guy was saying that eficency could / should be increased by more lengths of chimney. Any truth in this?  I have the stardard 2 lengths of pipe on my stve. I have no neighbors and have never had any problems with smoke. So i have never even thought about mor pipe. Even if it doese increase eficiency, I am hapy with the eficency I have now and dont plan to extend it for two reasons. Looks, and I would think that mor pipe means i would need to support it some how.

I wish I could say that I did have one neighbor complain to me she is straight west of me unfortunately winds are generally out of the west she is 600 feet away from me (I think she is nuts I've walked around when it's going and I don't smell it way over by her house but anyway)   

so I added more to keep her quiet at 20 feet now(she cost me a lot of money between the pipe/bracing support and the portable lift I rented for the weekend)

so to answer your original question I have not noticed any difference in performance since Ive added  the pipe.   Just more to run the brush through now  :(
13 Chevy Duramax
Stihl 046 036 009
Northern 25 Ton Splitter

doctorb

Quote from: WH_Conley on December 15, 2012, 11:22:52 PM
All I ever heard was enough pipe to get it above the the ridge of the roof. This was to eliminate down draft when the wind blew the wrong direction.

Ditto.

I have three sections to make it through the metal roof on my shed.  So my extra section is out of necessity, not out of efficiency.  Some OWB owner on the Forum was using only one section of pipe for a short time (I am sorry I can't remember that thread).  His OWB did not perform well with only one section of chimney pipe.  So, while I can not confirm that a higher chimney equates to an increased stove efficiency, i do think that too short a stack can be a problem with air draw.
My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

drobertson

I think I will research this further today, but this being said, our chimmney is fixed, it has the single 8" square tile. We have the stove in the basement, standard celing, then going on up through the ground floor then through the roof. 24' of chimmney.  Now this set up draws very well, but at the same time I have a barrel stove at the mill that for now has no pipe at all,(broke off) and it draws very well too!  I heard the same as mentioned earlier, get it above the roof line.  I think keeping them clean might be as important or more than the length.
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

chevytaHOE5674

For the last 11 years my OWB had about 10 inches of chimney above the tin roof on the boiler, with its overall height about 8' tall. Never did I have any efficiency problems like that, only issue was in heavy air the smoke would tend to hang low to the ground, if the wind was right that ment the other halfs car smelled like wood smoke on occasion.

So this year I welded 9.5 feet of pipe on top of the existing chimney and it gets the smoke up and away from the cars. But I've noticed no change in efficiency, burn times, wood usage, etc.

Before


After

gspren

 I think the whole thing about draft mostly concerns fireplaces and woodstoves without blowers. If your woodstove/OWB has a blower to force air into the burn chamber then chimney length or even getting above the ridge is not as important.
Stihl 041, 044 & 261, Kubota 400 RTV, Kubota BX 2670, Ferris Zero turn

doctorb

My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

MJD

1 section on mine and I have no problem with draft, its been like that for 8 years.

thecfarm

With an OWB I don't think it matters. Well I don't think it would matter with my Heatmor,anyways.There is no draft with mine,the blowers do all the so called drafting,for no better word. Just like the CB's,if no blowers no air can get into the fire box,fire goes just about out.I did add 3 sections of pipe on mine. At that time it was ¼ inch steel pipe.Each section just slipped into the next one. I just wanted to get the smoke up in the air some,away from me. With no natural draft I can burn dead cedar in my OWB and it's a control fire.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

Al_Smith

The length has something to do with the inverse square law of air movement above the ground .

My buddy once had a small "laundry stove " type of pot belly vented through a triple story farm house chimney. He never emptied the ashes .Just opened the damper and it sucked them up the flue .It's  a wonder he didn't burn something down .

Sprucegum

When I put the fireplace in my house I was told 12 feet of chimney would give it the best draft, no blowers or fans involved. The 12 feet was also enough to get above the ridge line so it all works out.

Holmes

Technically 2' above the highest point within 10' is the rule. If you have a non gassifier the higher the chimney goes the colder the flue gasses get the more creosote you get.
Think like a farmer.

Yoopersaw

Quote from: Holmes on December 22, 2012, 06:22:02 PM
Technically 2' above the highest point within 10' is the rule. If you have a non gassifier the higher the chimney goes the colder the flue gasses get the more creosote you get.

This works for me and sure helps when cleaning.

Logging logginglogging

I clean mine about once a year if it looks dirty... I simply lay them on the ground so the wind can blow through them, on a pretty windy day. I then spray a little gas of other flamible liquid in them and let it soak for a second... then i light them up and watch them burn just like a jet engine from the wind going through them.... after that they are clean as a whistle.

yellowrosefarm

On my Shaver 250, the 5" steel chimney pipe extended out the top of the "house" about a foot or so when I got it. There was no rain cap. I tried screwing a 6" rain cap to it but due to my inexperience, a warm winter, wet wood and an undersized blower fan the chimney needed cleaning a lot and unscrewing the cap was a real pain. I was trying to figure out what to do and ran across a 2' piece of double walled insulated stainless steel chimney pipe I had left over from the chimney I put on my garage years ago. Turned out that 6" inside diameter was just the right size to easily slip over the 5" steel pipe. So, I put the correct rain hat on the pipe and just slid it down over the existing chimney. It's heavy enough to stay there on it's own and when I need to clean the chimney, I just lift it off. I'd like for it to be higher to get the smoke out of the yard, but don't want to lose the easy to remove and clean feature.

bandmiller2

I have about 16' of pipe above the firebox of my home built outside furnace get a good draft without blower.Once in the heating season I will rap the pipe with a hammer handle and the dry stuff will fall back in the furnace to burn.It has the tendency to get the smoke up and away from the house and neighbors.My masonry firebox gives me a clean burn. Frank C.
A man armed with common sense is packing a big piece

r.man

My father used the chimney smoke to predict the weather. If the smoke is hitting the ground then a change is coming.
Life is too short or my list is too long, not sure which. Dec 2014

John Vander

I've experimented  a lot with this. Came up with a couple of sollutions after many failures. Pipe diameter × pipe lenth × stove air intake ports = proper flow speed.
Tree and saw accidents nullify years of forestry experience.

sam-tip

I went from 12' to 20' and did notice a better burn on my E3200 on calm days.  But the CB E3200 has bad air flow.  Way to easy to over fill with wood and not big enough fresh air fan.   When it is windy it still smokes bad.
The stack is 8 ft taller than the nearest building.
Central Boiler E3200 WiFi
Many many ported chainsaws. 201 to 3120
TM log splitter pro30 6 way head
D&L 1020 swing blade sawmill for slabbing
Timberking 1220

John Vander

Extended pipe length does direct the air flow better, but I've found that too much flow (too much diameter especially) causes the stove to blast all the heat out the top of the chimney, with little heat coming out of the stove itself. I regulated my one stove by using a small diameter exit pipe (from the stove) about 2 feet, then enlarging the diameter slightly with a bit larger pipe. I've noticed that when my hardwood logs (sawtooth oak) burns out before forming coals, the flow is too much. What I did was to regulate the pipe diameter/length relation to the air flow speed by closing the vents on my stove, then gradually opening them up while watching the flames. I found that when the flames start "streaming" (like water flowing, but upward) I have good fire, and the wood turns into nice coals that burn for long.
Tree and saw accidents nullify years of forestry experience.

thecfarm

john,welcome to the forum, You're in Japan? Born there,Moved there??
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

John Vander

Born in South Africa. Came out to Japan 10 years ago.
Tree and saw accidents nullify years of forestry experience.

Yoopersaw

Quote from: Holmes on December 22, 2012, 06:22:02 PM
Technically 2' above the highest point within 10' is the rule. If you have a non gassifier the higher the chimney goes the colder the flue gasses get the more creosote you get.


Usually code also. 

thecfarm

Quote from: Holmes on December 22, 2012, 06:22:02 PM
Technically 2' above the highest point within 10' is the rule. If you have a non gassifier the higher the chimney goes the colder the flue gasses get the more creosote you get.

What kind of OWB does that? I have burned all kinds of greenwood and wet wood in my Heatmor and never had a creosote problem. My smoke goes into a 3X6 inch tube right by the feed door,goes the full length of the furnace, My chimney is at the back.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

Thank You Sponsors!