Barometric Damper vs Efficiency

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Thu. Oct. 26, 2023 4:39 pm

Hey fellas, on my question to educate myself about bituminous coal burning I have come up with a question. My manual states the furnace is to be set at a .06 WC. Sometimes when I'm burning I notice the pipe temp seems to be excessive. It is possibly the factory recommended. 06wc is to high? If I set the baro at say .04, will it reduce heat going up the chimney and save alittle coal by reducing the pull of air thru the fire bed? I could be completely in the wrong line of thinking here, please share some input on what WC setting you guys have found success with for the most efficiency.


 
User avatar
carlherrnstein
Member
Posts: 1547
Joined: Tue. Feb. 07, 2012 8:49 am
Location: Clarksburg, ohio
Hot Air Coal Stoker Stove: combustioneer model 77B
Coal Size/Type: pea stoker/Ohio bituminous

Post by carlherrnstein » Fri. Oct. 27, 2023 7:38 pm

With bit coal there are basically 2 stages of burn like wood, first you get lots of volatile tars an oils that burn and you get lots of sooty flames and lots of heat. Then as the volatile stuff runs out you get a steady even heat that burns clean.

In my opinion a barometric damper causes more problems than it solves. I had one on my stoker stove and took out an replaced it with a cap.

You have to remember that the chimney is going to be hot no matter what and that's a good thing because a high flue temp means better draft, better draft means no smoke in the house and a large volume of air going up the chimney helps keep soot from accumulating. However it'll end up on the roof.

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Sat. Oct. 28, 2023 12:07 am

carlherrnstein wrote:
Fri. Oct. 27, 2023 7:38 pm
With bit coal there are basically 2 stages of burn like wood, first you get lots of volatile tars an oils that burn and you get lots of sooty flames and lots of heat. Then as the volatile stuff runs out you get a steady even heat that burns clean.

In my opinion a barometric damper causes more problems than it solves. I had one on my stoker stove and took out an replaced it with a cap.

You have to remember that the chimney is going to be hot no matter what and that's a good thing because a high flue temp means better draft, better draft means no smoke in the house and a large volume of air going up the chimney helps keep soot from accumulating. However it'll end up on the roof.
I do get some soot on the roof, the rain usually washes most of it off. I ran my furnace with and with out a baro and I much prefer it. I get more even heat and it helps me control the fire better. Especially if it tries to go nuclear on me, which happened already. The baro keeps it from drawing harder and harder. Another reason is the manufacturer recommends one and is to be set at the above stated water column. I agree having a good draft helps control soot buildup aswell. I was just curious as to what a good compromise between having a decent draft without wasting a ton of heat going up the chimney. Maybe I'm thinking to much on it. I have been accused of being over analytical quiet a bit over the years. My ocd requires me to make everything as perfect as I can. Guilty as charged I guess.

 
waytomany?s
Member
Posts: 4558
Joined: Fri. Aug. 16, 2019 3:02 pm
Location: Oneida, N.Y.
Hand Fed Coal Stove: Harmon Mark II
Hand Fed Coal Furnace: Looking
Baseburners & Antiques: Looking
Coal Size/Type: Nut
Other Heating: newmac wood/coal combo furnace

Post by waytomany?s » Sat. Oct. 28, 2023 8:28 am

Dustycloud wrote:
Sat. Oct. 28, 2023 12:07 am
I do get some soot on the roof, the rain usually washes most of it off. I ran my furnace with and with out a baro and I much prefer it. I get more even heat and it helps me control the fire better. Especially if it tries to go nuclear on me, which happened already. The baro keeps it from drawing harder and harder. Another reason is the manufacturer recommends one and is to be set at the above stated water column. I agree having a good draft helps control soot buildup aswell. I was just curious as to what a good compromise between having a decent draft without wasting a ton of heat going up the chimney. Maybe I'm thinking to much on it. I have been accused of being over analytical quiet a bit over the years. My ocd requires me to make everything as perfect as I can. Guilty as charged I guess.
No kidding, that's what OCD is? And here I thought I was fairly normal.😁 I'm guessing if whoever designed the stove said it needs a baro, then it probably needs a baro. Sure there are situations where it may not, but manufacturers recommendations typically allow for the best utilization of said product.

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Mon. Oct. 30, 2023 9:20 pm

I was hoping Doug would chime in, maybe give some firing tips aswell.

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Thu. Nov. 02, 2023 2:21 am

Well after 2 very cold days I finally think I made some headway. Last night and today I was really struggling to keep the house 70 degrees. It stayed right on 70 all day but I just wasn't getting the heat I wanted outta my furnace. Temp on the stove door remained 280 most of the day. I tried playing with the primary air but it didnt do anything. So I eventually adjusted the baro UP to .07 and just left my secondary cracked open a 1/8 or so. When I did this stove temp raised to a comfy 400 degrees. I know that means more heat up the chimney but oh well, atleast I have a nice hot stove especially since its only going to be 19 degrees in the morning. So here it is, 2:30am and I'm tired and worn out from messing with this thing all day. I think its time to go to bed. .

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Fri. Dec. 22, 2023 4:03 pm

I am a bit puzzled, I have been experimenting with my manometer adjustments the last few days. I had mine adjusted to a .07 to start, ripping fire, but coal didn't last but 4 hrs maybe. Next, I adjusted it way down to a .04 and the coal last about 8hrs but I'm getting soot in my pipes again. Another factor seems to be that with a .04 it doesn't seem to matter how far I have the ash door spinner open it doesn't get any hotter. So is there a direct correlation between how the manometer is set and heat output regardless of the amount of intake air that is given? Weather it's 1 spin or 8, will the manometer only let it pull a set amount of air through the coal bed limiting the heat output regardless of the air input adjustment?


 
User avatar
Lightning
Site Moderator
Posts: 14673
Joined: Wed. Nov. 16, 2011 9:51 am
Location: Olean, NY
Stoker Coal Boiler: Modified AA 130
Coal Size/Type: Pea Size - Anthracite

Post by Lightning » Fri. Dec. 22, 2023 4:35 pm

Combustion air is driven by pressure differential.. if the pressure differential is higher, it will draw more combustion air.. if the pressure differential is lower, it will draw less combustion air.. given that the spinner is at the same setting.

If you blow thru a straw, air comes out. If you blow harder more air comes out. You catch my drift lol

 
waytomany?s
Member
Posts: 4558
Joined: Fri. Aug. 16, 2019 3:02 pm
Location: Oneida, N.Y.
Hand Fed Coal Stove: Harmon Mark II
Hand Fed Coal Furnace: Looking
Baseburners & Antiques: Looking
Coal Size/Type: Nut
Other Heating: newmac wood/coal combo furnace

Post by waytomany?s » Fri. Dec. 22, 2023 4:38 pm

I think the answer is a resounding maybe. I personally have no idea. I don't understand bit, but if it were wood, which is similar, you get the fire going and then you adjust to get the heat needed for the current outdoor conditions. Windy? Close it up more than usual. Warmer? Close it down to not heat you out. Cold? Open air to get a higher temp. The hard part is most times you're compensating for more than 1 condition and that makes it more complicated. You're making headway with the longer burn and warmer house temps. Just experiment changing one thing at a time.

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Fri. Dec. 22, 2023 5:26 pm

Lightning wrote:
Fri. Dec. 22, 2023 4:35 pm
Combustion air is driven by pressure differential.. if the pressure differential is higher, it will draw more combustion air.. if the pressure differential is lower, it will draw less combustion air.. given that the spinner is at the same setting.

If you blow thru a straw, air comes out. If you blow harder more air comes out. You catch my drift lol
Is there any chance that if I would open the bottom spinner the whole way ( I wouldnt) that the chimney wouldn't keep up and spill gas into the house? Cause a positive pressure in the furnace? I was just wondering. That's is if I kept it at a .04wc.

 
User avatar
Lightning
Site Moderator
Posts: 14673
Joined: Wed. Nov. 16, 2011 9:51 am
Location: Olean, NY
Stoker Coal Boiler: Modified AA 130
Coal Size/Type: Pea Size - Anthracite

Post by Lightning » Fri. Dec. 22, 2023 6:51 pm

Dustycloud wrote:
Fri. Dec. 22, 2023 5:26 pm
Is there any chance that if I would open the bottom spinner the whole way ( I wouldnt) that the chimney wouldn't keep up and spill gas into the house?
I'm gonna say it would be highly unlikely to the point of not being possible. There are scenarios that could change that. Wind from a particular direction, or something that would cause the neutral pressure plane to move to the top of the house ect.. but in any of these instances, it would show up on the manometer as weaker pressure differential to the point of going positive, so you would have that warning.

 
User avatar
Lightning
Site Moderator
Posts: 14673
Joined: Wed. Nov. 16, 2011 9:51 am
Location: Olean, NY
Stoker Coal Boiler: Modified AA 130
Coal Size/Type: Pea Size - Anthracite

Post by Lightning » Fri. Dec. 22, 2023 7:01 pm

Another variable that you need to keep in mind is the fire's efficiency at using the available oxygen that it's given. This variable could skew your observations of fuel usage vs burn time and heat output. Combustion air is roughly 20% oxygen and 80% nitrogen. The question becomes, how much of that 20% oxygen is getting used? You can't just assume that every bit of it is used from one fire to the next. What you can do is make a lot of observations over a long period of time. Over time you'll notice a pattern of consistencies that will help you make better decisions about operating your particular stove and setup. We like to call it the "learning curve"

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Fri. Dec. 22, 2023 7:02 pm

Lightning wrote:
Fri. Dec. 22, 2023 6:51 pm
I'm gonna say it would be highly unlikely to the point of not being possible. There are scenarios that could change that. Wind from a particular direction, or something that would cause the neutral pressure plane to move to the top of the house ect.. but in any of these instances, it would show up on the manometer as weaker pressure differential to the point of going positive, so you would have that warning.
Ok cause I seen I was getting small puffs of smoke out the secondary air I added to the door. I wasn't sure why, think it might just be cause the bit is so smokey. I only leave the one located on the load door open long enough to get the voltiles burned off for the most part and start to see a temp drop then I completely shut that one. I would probably get a better burn if I could leave ot open but I don't trust it unless I'm right there. Of course it doesn't need much secondary after I start shutting it down anyway.

 
User avatar
Lightning
Site Moderator
Posts: 14673
Joined: Wed. Nov. 16, 2011 9:51 am
Location: Olean, NY
Stoker Coal Boiler: Modified AA 130
Coal Size/Type: Pea Size - Anthracite

Post by Lightning » Fri. Dec. 22, 2023 7:12 pm

Ahhh ok... The puffs you are seeing are caused from the volatile gases reaching the proper fuel/air mixture to ignite. It's not a violent flash like gasoline vapors exploding, it's more of a sluggish type puff back. These sluggy style puffbacks can and will cause the fire box to go positive pressure for a fraction of a second, which at that moment you see a little smoke get expelled out thru your combustion air openings (primary and/or secondary).. but after that brief moment the stove interior returns to negative pressure until the next opportunity for the volatile gases to flash. It happens too fast for the manometer to respond, but you probably do notice the baro door try to slam shut at the same time.

 
Dustycloud
Member
Posts: 126
Joined: Sat. Sep. 09, 2023 3:12 am

Post by Dustycloud » Fri. Dec. 22, 2023 7:39 pm

Lightning wrote:
Fri. Dec. 22, 2023 7:12 pm
Ahhh ok... The puffs you are seeing are caused from the volatile gases reaching the proper fuel/air mixture to ignite. It's not a violent flash like gasoline vapors exploding, it's more of a sluggish type puff back. These sluggy style puffbacks can and will cause the fire box to go positive pressure for a fraction of a second, which at that moment you see a little smoke get expelled out thru your combustion air openings (primary and/or secondary).. but after that brief moment the stove interior returns to negative pressure until the next opportunity for the volatile gases to flash. It happens too fast for the manometer to respond, but you probably do notice the baro door try to slam shut at the same time.
It usually only happens when I cut the secondary air or if I don't keep the slide damper the whole way open while the smoke is burning off.


Post Reply

Return to “Hand Fired Coal Boilers & Hot Air Furnaces/Stoves Using Bituminous”