Over Draft

I am having problems with my chimney drafting too hard and pulling the heat out of my stove and up the pipe. My chimney is a good bit above the ridge line of my roof and I live at the top of a hill without much around to break up the wind. All of this combines to cause an extremely strong draft. Last year I installed a barometric damper after not having luck with a manual pipe damper, and this and it made a big difference. However, the baro often stays wide open, especially when cold or windy, and I continue to lose a lot of heat up the flu. It's to the point where I hear it whistling up the pipe, causing me to have to burn much hotter than should be necessary to keep my house warm.

At this point I am considering two options: I've heard that installing a chimney cap can help with this problem, and I figure it wouldn't hurt to have a cap anyway, so I may try that. I've also considered installing a manual pipe damper in addition to the baro. Does anyone know either of these possible solutions would be adequate in reducing my heat loss? If I do put in an MPD, should it be between the baro and the chimney or between the baro and the stove? Any advice or other ideas would be appreciated!

bucksnort wrote:I am having problems with my chimney drafting too hard and pulling the heat out of my stove and up the pipe. My chimney is a good bit above the ridge line of my roof and I live at the top of a hill without much around to break up the wind. All of this combines to cause an extremely strong draft. Last year I installed a barometric damper after not having luck with a manual pipe damper, and this and it made a big difference. However, the baro often stays wide open, especially when cold or windy, and I continue to lose a lot of heat up the flu. It's to the point where I hear it whistling up the pipe, causing me to have to burn much hotter than should be necessary to keep my house warm.

At this point I am considering two options: I've heard that installing a chimney cap can help with this problem, and I figure it wouldn't hurt to have a cap anyway, so I may try that. I've also considered installing a manual pipe damper in addition to the baro. Does anyone know either of these possible solutions would be adequate in reducing my heat loss? If I do put in an MPD, should it be between the baro and the chimney or between the baro and the stove? Any advice or other ideas would be appreciated!

i would not count on the chimney cap solving this problem (but as you say... good to have anyways!), be thankful your draft is to strong (this is MUCH better than having to weak a draft). Placing the MPD between the stove and baro is done by many here successfully and im sure they will attest to it soon. Ive also seen 2 MPD's used in very rare occasions. One thing many will mention is if you have checked your stove for air infiltration leaks (dollar bill test doors, roam around lower sections with a smoking candle/lighter/etc. to search for any areas that may be pulling in the smoke/flame? I know one thing for sure... I would not want a baro being open 24/7 sucking out all air in the house 24/7 (something is feeding it to remain open like that all the time like a wide open door or window ) or its faulty or something... these guys will want to know your mano readings (if you don't have one, get one!) .... others more atuned to this problem will weight in soon

For your situation you might want to consider two barometric dampers.

dcrane wrote:

bucksnort wrote:I am having problems with my chimney drafting too hard and pulling the heat out of my stove and up the pipe. My chimney is a good bit above the ridge line of my roof and I live at the top of a hill without much around to break up the wind. All of this combines to cause an extremely strong draft. Last year I installed a barometric damper after not having luck with a manual pipe damper, and this and it made a big difference. However, the baro often stays wide open, especially when cold or windy, and I continue to lose a lot of heat up the flu. It's to the point where I hear it whistling up the pipe, causing me to have to burn much hotter than should be necessary to keep my house warm.

At this point I am considering two options: I've heard that installing a chimney cap can help with this problem, and I figure it wouldn't hurt to have a cap anyway, so I may try that. I've also considered installing a manual pipe damper in addition to the baro. Does anyone know either of these possible solutions would be adequate in reducing my heat loss? If I do put in an MPD, should it be between the baro and the chimney or between the baro and the stove? Any advice or other ideas would be appreciated!

i would not count on the chimney cap solving this problem (but as you say... good to have anyways!), be thankful your draft is to strong (this is MUCH better than having to weak a draft). Placing the MPD between the stove and baro is done by many here successfully and im sure they will attest to it soon. Ive also seen 2 MPD's used in very rare occasions. One thing many will mention is if you have checked your stove for air infiltration leaks (dollar bill test doors, roam around lower sections with a smoking candle/lighter/etc. to search for any areas that may be pulling in the smoke/flame? I know one thing for sure... I would not want a baro being open 24/7 sucking out all air in the house 24/7 (something is feeding it to remain open like that all the time like a wide open door or window ) or its faulty or something... these guys will want to know your mano readings (if you don't have one, get one!) .... others more atuned to this problem will weight in soon

I have checked a few times for air infiltration. When my stove was new last year and I was initially having the problem to a stronger degree it was suggested that may be the problem. I have checked the door again and it seems to be sealing fine and I don't see anything when doing the lighter test around the bottom. Maybe the mpd is the answer

bucksnort wrote:

dcrane wrote: i would not count on the chimney cap solving this problem (but as you say... good to have anyways!), be thankful your draft is to strong (this is MUCH better than having to weak a draft). Placing the MPD between the stove and baro is done by many here successfully and im sure they will attest to it soon. Ive also seen 2 MPD's used in very rare occasions. One thing many will mention is if you have checked your stove for air infiltration leaks (dollar bill test doors, roam around lower sections with a smoking candle/lighter/etc. to search for any areas that may be pulling in the smoke/flame? I know one thing for sure... I would not want a baro being open 24/7 sucking out all air in the house 24/7 (something is feeding it to remain open like that all the time like a wide open door or window ) or its faulty or something... these guys will want to know your mano readings (if you don't have one, get one!) .... others more atuned to this problem will weight in soon

I have checked a few times for air infiltration. When my stove was new last year and I was initially having the problem to a stronger degree it was suggested that may be the problem. I have checked the door again and it seems to be sealing fine and I don't see anything when doing the lighter test around the bottom. Maybe the mpd is the answer

a MPD between the baro and stove would be my first action for sure... but again... baro wide open 24/7 sounds whaco to me (im not sure how it can maintain an open swing all the time without having a lot of air to supply it) ... even if the mpd helps keep heat out of the chimney (to hopefully reduce the draft thats seemingly holding that baro wide open)... it may not be enough, so im looking for some of the geek squad to help explain what kind of air is required to feed a baro in order for it to remain wide open 24/7?

I can tell you that having the chimney cap on(lower) or off(higher) definitely affects the draft in the stainless liner installed in my chimney. Even with the cap installed I can change the draft by raising or lowering the height of the cap above the liner outlet in small (1") increments.

If the winds are hitting a leaky house, they in a sense are "supercharging" the house. - raising the pressure a bit more as they gust. Likewise, if the top opening of the chimney is getting a Venturi affect from those same winds. It will lower the pressure at the opening more than just the force of the heat induced draft.

What could be happening unique to that location is slightly higher than usual indoor pressure, aided by slightly higher chimney pressure drop.

I see two ways to look at solving it. Before the fire box, or after the fire box. Deal with finding/reducing leaks, or deal with the need for additional baro control.

The two baro's idea might work, but one baro, wide open, is close to the flow rate size of the pipe it's in. Two baro's won't make the pipe bigger, just the openings into it. Maybe putting a reducer just before the baro and using a larger diameter pipe and larger baro that will flow more air from that point to the chimney may help.

The second view is, why send more heat up the chimney to solve the problem. I'd be looking to see if I could find leaks in the house and the stove and reduce cool air infiltration in both to keep heat in while gaining more control of the stove.

Paul

bucksnort wrote:I am having problems with my chimney drafting too hard and pulling the heat out of my stove and up the pipe. My chimney is a good bit above the ridge line of my roof and I live at the top of a hill without much around to break up the wind. All of this combines to cause an extremely strong draft. Last year I installed a barometric damper after not having luck with a manual pipe damper, and this and it made a big difference. However, the baro often stays wide open, especially when cold or windy, and I continue to lose a lot of heat up the flu. It's to the point where I hear it whistling up the pipe, causing me to have to burn much hotter than should be necessary to keep my house warm.

At this point I am considering two options: I've heard that installing a chimney cap can help with this problem, and I figure it wouldn't hurt to have a cap anyway, so I may try that. I've also considered installing a manual pipe damper in addition to the baro. Does anyone know either of these possible solutions would be adequate in reducing my heat loss? If I do put in an MPD, should it be between the baro and the chimney or between the baro and the stove? Any advice or other ideas would be appreciated!

What you need is a wind cap, it's a special chimney cap that is designed to resist wind effects, I have one, they work well.



This kind of cap can take adverse winds and convert them to upward flow in the chimney.

http://woodheat.org/wind-chimney.html

you may also want to check all the door seals and openings in your stove, where raker rod, etc. goes through, to make sure they aren't leaking. We just had a Newcastle drive us nuts with over-firing, it needed many things- new door/glass seals, raker rod hole sealed with special cut gasket, and the rear inside baffle extended from 15'x6", to 18"x8.5"

now it idles right down, has no overfire condition, burns half as much coal, and heats better

and it doesn't have an MPD or baro. Perhaps we'd get a little more heat with an MPD, but don't want to risk the CO gas dangers with a 73 year old mother in law stoking the stove by herself. But now that it's all tuned up she is doing that with ease.

the MPD and baro controls are really for stoves you can't get airtight. The MPD was a device from the early days of coal and wood burning, where the stoves had no door or glass gaskets, and the damper controls loose, and they leaked a lot of air. So they had no choice but to use an MPD.

the baro is something that was used on oil furnaces for liquid fuel, because it's being injected at a fixed rate, so the air/fuel ratio must be maintained like in a car engine. The only way to keep the burn ratio steady with oil, is with a baro to control the draft. The problem with our baro being wide open, is it's sucking all the heated air right out of your house, up the chimney- the notion those are efficient is therefore misplaced and not 100% correct.

with a coal stove, you can adjust it all from the lower draft controls, if everything else is airtight, and there's a well designed baffle inside the stove already- basically the interior baffle is doing what the MPD used to do, but right inside the stove, and the baffle is much larger, and an integral part of the stove.

Member King coal had this same problem and found that using both a manual damper and baro plus partially closing off the secondary air openings solved the problem.

bucksnort wrote:. Last year I installed a barometric damper after not having luck with a manual pipe damper, and this and it made a big difference. However, the baro often stays wide open, especially when cold or windy, and I continue to lose a lot of heat up the flu. It's to the point where I hear it whistling up the pipe, causing me to have to burn much hotter than should be necessary to keep my house warm. !

You can have a dangerous condition there using both, if the baro closes off the stovepipe due to high wind conditions, then what's left trying to vent the stove, is closed off with the MPD ahead of the baro, a CO buildup may occur if these 2 devices work against each other, or work with each other and close the stove off too much.

question, when you say you didn't have any luck with the MPD, what exactly happened or went wrong ?

one more thing, draft is a function of chimney height and length, if you reduced the chimney height, that would reduce draft. I say that as a last resort because for every 1 chimney with too much draft, there are 10 with not enough draft.

Here is something to think about, if the stove is air tight and your sure of it then the suction from the chimney shouldn't effect the burn because when the flapper closes if cuts the air into the stove off. Sure the chimney still has suction on it and a manometer will show high numbers but the air moving through the coal bed should not be effected and is only regulated by the flapper and the amount of air it is letting in. I have the same type of draft (very strong) so I make sure all my gaskets are sealing properly and let the stove take care of the draft. I used to have both a baro and an MPD in the pipe and found the same problem you are having with the house being sucked inside out by the baro and all my heat going up the chimney. So the baro is no longer with us only the MPD. Each situation is different so for some the baro is the way to go and for others not. Guys on here will tell you oh my god you have to use a baro, for them it must be working but for our situation it doesn't. My suggestion is to tinfoil the baro use the mpd (closed) set your stove to the temp you want and check your coal usage, then uncap the baro and check your usage again, make your own decision from there.

KISS, personally I would definitely put a cap on the chimney & check the difference. If not satisfied, I would put an MPD in. I'd betcha that between the 2 you will find satisfactory results--I am amazed at all the recommendations for a baro or 2 baro's, or baro & MPD-- hell, let's put a half a dozen of everything on. My concern there is that if this baro concept is being suggested every time I turn around, why does it seem to me--it does do the job it is meant to do in so many situations:( just curious here????? I'v got a chimney pipe on the top of an open hill that will suck the nipple off a teet & with my chimney cap & MPD, I have fantastic results. I understand that physical settings vary, but when I'm reading about possibly 2 baro's--baro & mpd-at least one--I gotta start wonderin

When I say the mpd didn't work, I would keep it closed but the stove still burned the same and it seemed like it wasn't radiating good heat. When I changed to a baro it seemed to regulate itself better and my heat situation improved. My conclusion from this was that the baro was better able to handle the wind gusts, keeping more heat in the stove as opposed to sucking it up through the flu. When the wind is strong the baro flaps open and pulls air from the house as opposed to from the stove, is this correct? However, it seems my baro stays open much too often, meaning its pulling air from the house and still also a pulling from the stove also, taking heat up the flu. Is this an incorrect assumption?

I honestly don't think there is a problem with the stove. Its barely a year old and I had a brand new, yet smaller, hitzer in before the larger ds stove and had the same problem. I have considered that its just a leaky house but I can put a kerosene heater on my first floor without any other heat source and keep my house warmer than the 160,000 BTU stove can from the basement. My house is only 1,100 square feet with an open concept basement that is 3/4 in the ground with good insulation around the exposed perimeter. I get good air floor to my open concept first floor with several open floor vents and by keeping the door to the basement open. I would think that a stove this size should make my 24 x 24 basement much hotter than it does. So I can only conclude that the heat from my stove has to be going somewhere, possibly up the chimney?

Tell us about your coal usage/consumption.
Tell us how much coal per loading.
Are you getting ash removed well from the corners during shake down?

Freetown,you have a self regulating stove if the stove temp starts to rise the air is cut off to the fire thus reducing the heat.I have a manual adjustment for the air intake so when the wind blows steady it creates a strong vacuum thus increasing the stove temp and with no way to reduce the air going through the fire bed I have to reduce the vacuum in the chimney so for me a baro is the answer.I spend 14 to 15 hrs a day away from home and since I will not let anyone else tend the stove thats the only way to get consistent heat out of my stove(until I work out some issues trying to add Hitzers Dial-a-temp to my insert)last year I ran without a baro and the temps were all over the place depending on the wind and how hard it was blowing.

coalcracker wrote:You can have a dangerous condition there using both, if the baro closes off the stovepipe due to high wind conditions, then what's left trying to vent the stove, is closed off with the MPD ahead of the baro, a CO buildup may occur if these 2 devices work against each other, or work with each other and close the stove off too much.

Coalcraker,If you read the installation on any barometric damper that give you a specific minimum distance from the center line of the flapper to the pipe so this won't happen and like anything in the world if you can't comprehend that then you shouldn't be messing with it!
Barometric dampers are nothing more then a vacuum regulating device for the flue thus giving the appliance a constant draft. Keepaeyeonit