Over draft

Re: Over draft

PostBy: Sunny Boy On: Mon Dec 16, 2013 11:14 pm

ridgeracing wrote:I dont think he ment offense to your figures, He is just saying that with a stove temp of 550 you wont have a chimney stove pipe of temp of 150. One or both of your guages may be out of wack? I believe my chimney at that stove temp is like 250-300 roughly. To make that much heat, you will loose a good bit up the chimney no matter what.
PS- I got my manometer at GRAINGERS for less than $47.00 ( Dwyer Mark II model 25)


You can get them for even less on Amazon.
http://www.amazon.com/dp/B009PAN3C8/ref=biss_dp_t_asn

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Over draft

PostBy: fastcat On: Tue Dec 17, 2013 12:38 am

bucksnort wrote:
fastcat wrote:Bucksnort there is NO way your stove is at 550* with 150* stack temps. You need to be giving us real numbers and these aren't real. :mad:
You really think I'm making up these temps?? That's what the magnetic gauge says. I can read. I came for advice, not to be insulted... sorry for asking questions, I'm not very experience


How can you say I'm insulting you? At 550* you would be looking at 300 to 350* stack. I have already told you these magnetic thermometers are just for base numbers and one of your thermometers is out in left field. I did not post to insult you just telling you the facts, I put the smiley up there as a joke as many of us do. Guess the other guys can help you from here.
fastcat
 
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Blaschak Nut/Stove Mix

Re: Over draft

PostBy: bucksnort On: Tue Dec 17, 2013 8:06 am

My apologies for taking it the wrong way. Not trying to get on anyone's bad side here. I do appreciate the help.
bucksnort
 
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Re: Over draft

PostBy: Lightning On: Tue Dec 17, 2013 8:12 am

Everyone take a deep breath lol. Temperture readings will vary based on the placement of the thermometers and everyone's readings will be unique to their appliance and installation situation. In my opinion hahaha the most reliable location is the hottest point on the stove and the hottest point on the pipe.

Placement on the pipe should be between the stove and any draft damper and on the top side if the pipe is sloped or horizontal roughly 18 inches out from the stove. Comparing temps to what other members have is futile. Use the temps as your own reference to determine your best heat output efficiency.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Over draft

PostBy: titleist1 On: Tue Dec 17, 2013 11:45 am

i prefer the bar-b-q probe style temp gauge over the magnetic temp gauge for the flue pipe temps. the upside is i think it is a more repeatable reading, downside is you can't move it as easily from one place to another. the last i looked for one i think it was around $12, you can find them at a big box store even this time of year. when i put it in i was wondering how it would hold up to the exhaust, but i am on my third year of using this one. i take it out of the pipe in the spring and use steel wool to clean off the probe.

i still use the magnetic one on the side of the stove.

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titleist1
 
Hot Air Coal Stoker Stove: Harman Mag Stoker (old style) one in basement, one in workshop
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Coal Size/Type: Rice/Anthracite; Nut/Anthracite

Re: Over draft

PostBy: KingCoal On: Thu Dec 19, 2013 7:58 pm

Berlin wrote:A baro reduces draft the appliance sees by allowing a controlled amount of room air to enter the stack, this not only cools the flue thus reducing draft, but, breaks the draft to the appliance directly by allowing the flue to pull air from the room thus reducing vacuum in the flue.

A larger baro is necessary to break excessive draft because the ability to reduce the draft is directly related to the cross-sectional area of the baro's maximum opening. The change in pipe size has nothing to do with it, it's the size of the baro that's important. There's a forum member in niagara falls who went from about a 9" connecting pipe to something like 18" dia. T with a huge 18" baro and then back to 9" connecting pipe and to the stack. The stack was an interior stack over 40' high in a large old home in niagara falls and it still pulled that baro almost half open when the wind hit. When you have a situation with excessive draft, forget about mpd's + baro (you don't need it) all you need to do is use a large barometric damper to keep draft regulation automatic.


please excuse a newbie to these concepts and practices but, i am having a time getting my mind around the idea of using a Baro. that's twice the size of the outlet flange.

at the surface it seems nothing can be gained because if you have a 12" baro. set at say .07 - .08 if it opens 1/4 of the way it might be equal to a 6" unit pretty far open ? so the house is still loosing warm air faster than the stove can keep up ?

OR, is it the case that there is such a large area of 12" "T" and reducers that the flow leaving the stove has to fill it ( thus loosing speed and draft power) and the larger baro. is hardly able to open ?

if i think of this over a lengthy period i MIGHT figure out what happens, but i consider myself teachable, and the wife has other things for me to do than sitting a staring into space. :roll:
KingCoal
 
Hand Fed Coal Stove: DSM 1400, Riteway # 37, Comforter Stove Works
Coal Size/Type: Nut Anth.
Other Heating: none
Stove/Furnace Model: 2013 1400 Circulator

Re: Over draft

PostBy: dustyashpan On: Thu Dec 19, 2013 8:36 pm

fastcat wrote:
bucksnort wrote:
fastcat wrote:Bucksnort there is NO way your stove is at 550* with 150* stack temps. You need to be giving us real numbers and these aren't real. :mad:
You really think I'm making up these temps?? That's what the magnetic gauge says. I can read. I came for advice, not to be insulted... sorry for asking questions, I'm not very experience


How can you say I'm insulting you? At 550* you would be looking at 300 to 350* stack. I have already told you these magnetic thermometers are just for base numbers and one of your thermometers is out in left field. I did not post to insult you just telling you the facts, I put the smiley up there as a joke as many of us do. Guess the other guys can help you from here.



my Harman is 550F front face, 250F outlet flange right now. Measured at 18" or 24" up would be less than 250F, whats big deal. Stack temp can be 1/2 of outer firebox.
dustyashpan
 
Hand Fed Coal Stove: Atlanta Homesteader, Harman
Baseburners & Antiques: Radiant Medal Dockash No.150 baseheater
Coal Size/Type: nut stove pea

Re: Over draft

PostBy: dustyashpan On: Thu Dec 19, 2013 8:42 pm

Lightning wrote:Would there be any down side to using an over sized barometric other than the added air infiltration?

I'm considering it.



yes losing just heated room air to open baro, up chimney to make stove "better". counterproductive. 2 steps ahead & 1 back. baro open pulls cold air in house like fireplace, how efficient is fireplace.
dustyashpan
 
Hand Fed Coal Stove: Atlanta Homesteader, Harman
Baseburners & Antiques: Radiant Medal Dockash No.150 baseheater
Coal Size/Type: nut stove pea

Re: Over draft

PostBy: robb On: Thu Dec 19, 2013 8:46 pm

I had a friend with this issue, not quite to your extent, but bad nonetheless. He put on a stainless cap and then put a heat exchanger in his pipe. He said it is working great now. I am not sure if what he did is right, but it seems to be working.
robb
 
Stove/Furnace Make: Hitzer
Stove/Furnace Model: 608 stoker

Re: Over draft

PostBy: Sunny Boy On: Thu Dec 19, 2013 9:18 pm

dustyashpan wrote:
Lightning wrote:Would there be any down side to using an over sized barometric other than the added air infiltration?

I'm considering it.



yes losing just heated room air to open baro, up chimney to make stove "better". counterproductive. 2 steps ahead & 1 back. baro open pulls cold air in house like fireplace, how efficient is fireplace.


But, without the baro, how much cold air is an over-drafting stove pulling in, . . . while sending it's hotter-than-room-air up the chimney ?

The trade-off that a baro does is, warm room air for hot stove gases. That trade-off also slows heat out of the stove and up the chimney, thus reducing the stoves pull on cold air infiltration. If I had an over drafting stove, I'd rather lose 70 degree room air then 500 degree stove air, while at the same time, reduce the pressure drop that's forcing cold air into the dwelling.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Over draft

PostBy: Sunny Boy On: Thu Dec 19, 2013 9:24 pm

robb wrote:I had a friend with this issue, not quite to your extent, but bad nonetheless. He put on a stainless cap and then put a heat exchanger in his pipe. He said it is working great now. I am not sure if what he did is right, but it seems to be working.


Sounds like he may have added some restriction by installing a stainless cap. And, also slowed the draft further by using the exchanger to take heat out of the flue gases in the pipe, thus reducing the pressure drop in the pipe.

Paul
Sunny Boy
 
Hand Fed Coal Boiler: Anthracite Industrial, domestic hot water heater
Baseburners & Antiques: Glenwood range 208, # 6 base heater, Modern Oak 118.
Coal Size/Type: Nuts !
Other Heating: Oil &electric plenum furnace

Re: Over draft

PostBy: Lightning On: Thu Dec 19, 2013 9:45 pm

dustyashpan wrote:
Lightning wrote:Would there be any down side to using an over sized barometric other than the added air infiltration?

I'm considering it.



yes losing just heated room air to open baro, up chimney to make stove "better". counterproductive. 2 steps ahead & 1 back. baro open pulls cold air in house like fireplace, how efficient is fireplace.


Yes a smooth low draft is definitely worth the trade off for half the added air infiltration.
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Over draft

PostBy: dustyashpan On: Fri Dec 20, 2013 7:35 am

bucksnort wrote:I am having problems with my chimney drafting too hard and pulling the heat out of my stove and up the pipe. !


chimneys dont pull too hard, its some stoves leak too much. vacuum cleaner pulls hard too, put hand over hose, it stops pulling cuz its shut, your hand is valve. thats the draft knobs. should be able to shut any stove right down, if not its leakin air. fix air leaks & you can control it. gotta be airtight. otherwise its a car with gas pedal stuck 1/2 way down. will go faster but wont idle.
dustyashpan
 
Hand Fed Coal Stove: Atlanta Homesteader, Harman
Baseburners & Antiques: Radiant Medal Dockash No.150 baseheater
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Re: Over draft

PostBy: Keepaeyeonit On: Fri Dec 20, 2013 8:23 am

I theory that's correct but let say you set the stove for 350* and the chimney is pulling .20" WC if the chimney drops to .05"WC that stove will not maintain 350* it will cool unless there is something in the stove to regulate the amount of air getting pulled through the fire box, now if it's set for a chimney that's pulling .05"WC and it picks up to .20"WC the stove will get hotter due in part to the the amount of air getting pulled into the stove. I'm sure the antique stoves have a better way of control( Im not starting a debate on old vs new) but my stove between the built in MPD and baffle plate cannot control for a big swing in chimney draft so I use a baro so now the stove gets a consistent draw and I now have control. Keepaeyeonit
Keepaeyeonit
 
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Re: Over draft

PostBy: Rob R. On: Fri Dec 20, 2013 8:55 am

KingCoal wrote:
Berlin wrote:A baro reduces draft the appliance sees by allowing a controlled amount of room air to enter the stack, this not only cools the flue thus reducing draft, but, breaks the draft to the appliance directly by allowing the flue to pull air from the room thus reducing vacuum in the flue.

A larger baro is necessary to break excessive draft because the ability to reduce the draft is directly related to the cross-sectional area of the baro's maximum opening. The change in pipe size has nothing to do with it, it's the size of the baro that's important. There's a forum member in niagara falls who went from about a 9" connecting pipe to something like 18" dia. T with a huge 18" baro and then back to 9" connecting pipe and to the stack. The stack was an interior stack over 40' high in a large old home in niagara falls and it still pulled that baro almost half open when the wind hit. When you have a situation with excessive draft, forget about mpd's + baro (you don't need it) all you need to do is use a large barometric damper to keep draft regulation automatic.


please excuse a newbie to these concepts and practices but, i am having a time getting my mind around the idea of using a Baro. that's twice the size of the outlet flange.

at the surface it seems nothing can be gained because if you have a 12" baro. set at say .07 - .08 if it opens 1/4 of the way it might be equal to a 6" unit pretty far open ? so the house is still loosing warm air faster than the stove can keep up ?

OR, is it the case that there is such a large area of 12" "T" and reducers that the flow leaving the stove has to fill it ( thus loosing speed and draft power) and the larger baro. is hardly able to open ?

if i think of this over a lengthy period i MIGHT figure out what happens, but i consider myself teachable, and the wife has other things for me to do than sitting a staring into space. :roll:


The baro is sized to bleed off excess draft...the chimney doesn't care how big the flue collar on the appliance is. A tall chimney with a large flue that sees wind gusts can have rapid (and large) changes in draft. I think a large baro can react to the surge in draft faster since it doesn't have to open all the way...but I haven't tried this in my own home. I have witnessed wind gusts slam by 8" baro against the stops and hold it wide open for a 5-10 seconds...when it comes time to replace the flue pipe I will consider a larger baro as well.
Rob R.
 
Stoker Coal Boiler: EFM DF520
Coal Size/Type: Rice/buck
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