# Question about vent on antique coal stove



## WoodBerner (Oct 6, 2019)

I just installed an antique Bonny Oak 215 stove. It is apparently a coal stove, but I’m burning wood in it and although it gets very hot (the sides got over 625 degrees) it seems to be working fine.

My question is this: on thetop of the stove just below the chimney there is a smell vent hat can be opened and closed. What is this vent called, and when should I have it open or shut?

Thank you!


----------



## SpaceBus (Oct 6, 2019)

I think that's for coal use, but it could also be an opening for air above the fire for a rudimentary secondary combustion. Usually coal stoves, especially antiques like these, also have a barometric damper that let's room air into the flue under certain draft conditions, so maybe your vent is also for that purpose.

Either way, nice looking stove! I really wanted an Oak style stove, especially a Glenwood Modern Oak with isenglas door. Let us know what your wood consumption is like, as that's a big part of why we didn't go with one.


----------



## SpaceBus (Oct 6, 2019)

Also, be careful opening the ash pan door while burning wood. Under fire air can quickly cause an overfire. I also think these have a tin skin with a cast iron burn chamber. These tin work skins can be easily damaged by overheating them. It's very difficult and expensive to replace them.


----------



## bholler (Oct 6, 2019)

It is to help burn off coal gas and prevent explosion.  I see some potential clearance issues there.  You need 18" of hearth protection all around it.  How is that metal attached to the wall beside the stove and how far is it?


----------



## WoodBerner (Oct 6, 2019)

It’s 1” from the wall and is using ceramic offsets specifically made for the purpose. Even when the stove was very hot the shield remained almost cool to the touch.


----------



## WoodBerner (Oct 6, 2019)

SpaceBus said:


> Also, be careful opening the ash pan door while burning wood. Under fire air can quickly cause an overfire. I also think these have a tin skin with a cast iron burn chamber. These tin work skins can be easily damaged by overheating them. It's very difficult and expensive to replace them.



How would I know if I have overheated the skin?


----------



## bholler (Oct 6, 2019)

WoodBerner said:


> It’s 1” from the wall and is using ceramic offsets specifically made for the purpose. Even when the stove was very hot the shield remained almost cool to the touch.


Ok good so as long as you have the 1" gap top and bottom it is a proper heat shield.  How far is the stove from the wall behind that shield?


----------



## SpaceBus (Oct 6, 2019)

WoodBerner said:


> How would I know if I have overheated the skin?



It will buckle and warp, it's pretty thin stuff. This is the warning given to me by a restoration shop while I was looking into the feasibility of using one to heat my house.


----------



## bholler (Oct 6, 2019)

SpaceBus said:


> It will buckle and warp, it's pretty thin stuff. This is the warning given to me by a restoration shop while I was looking into the feasibility of using one to heat my house.


You made a good choice


----------



## SpaceBus (Oct 6, 2019)

bholler said:


> You made a good choice


Indeed. I still want one, but not as a primary heater.


----------



## coaly (Oct 6, 2019)

I believe the small opening you're referring to is the chimney dilution air intake. (damper) It is used to reduce draft by allowing indoor air up chimney such as a barometric damper cools chimney to slow draft. It extends burn time for overnight by slowing draft. Compared to a manual pipe damper, OPEN is a closed damper, CLOSED is an open damper. Decreasing draft decreases air coming up through grate to give a slower burn. Some cook stoves will have a chimney intake to preserve the fire overnight. I have tilted a lid overnight to allow indoor air into chimney without going through coal bed to sustain the fire overnight and run the stove cooler.
With coal, the primary inlet at bottom below grate controls burn, only *crack the upper intake* with coal for oxygen to get to the top of fire to ignite coal gas. (oxygen is used up through fire bed to supply air for blue flames above coal)Too much secondary air slips up chimney cooling it, reducing draft and taking away the primary air from the bottom. Only open dilution air when a smaller fire is needed or for longer duration overnight.
Wood use can use bottom to start only, then use upper secondary as the primary intake for burn rate. Close dilution with wood. (wood will use any air it can get, bottom, middle or top) Also opening with wood can ignite smoke particles creating a secondary burn in pipe, glowing right there! Scared me until I figured out to never open it with wood.


----------



## coaly (Oct 6, 2019)

You'll find burning coal is a much more even heat, constant temperature, and the stack only runs around 100* making it much more efficient. Fill it with coal once a day and it just keeps going without the mess of wood. The ash is finer, so you have to learn to shake it down with a draft going or the dust is in the house. Very fine dust is the only con I've found with coal. You have to know how to do it. If you have to, light paper in the stove in the morning to induce draft before shaking. It is so fine you can't see it while you're causing the mess.


----------



## WoodBerner (Oct 7, 2019)

Thanks for all the help. I’m a little confused about the damper (you said closed is open, but then said you run with it closed, do you mean open?), but the rest is great advice.
I got the stove for $100. My thought is that if I works, great, if not I swap it out with another stove and I haven’t really lost much but time.

I love on two acres of dense forest, so heating with wood makes more sense right now. I priced coal locally, and it seems like I wouldn’t save much money over heating with electric.


----------



## coaly (Oct 7, 2019)

Run it physically closed to prevent oxygen from mixing with wood smoke. If the draft is too strong, (air leaks into stove with air inlet closed, burning too fast) you would need a pipe damper to slow draft. 
Compared to a manual pipe damper, when the opening is open, it is like a closed damper in the pipe. Opening the inlet is like closing a pipe damper. It allows indoor air to rush into the chimney (low pressure area caused by rising gasses) cooling the flue, slowing the draft. A manual pipe damper is a variable resistance that slows velocity of rising gasses, reducing draft. Your air inlet cools chimney, reducing draft. This gives the same results as a manual damper without being able to close the pipe off completely. Burning coal could allow CO into the home if a manual damper was used incorrectly. So this is like a limited damper that prevents closing off too far.


----------



## WoodBerner (Oct 8, 2019)

Allow me to vent about the vents: too many vents!

I’m new to this wood stove thing, and I’m sure I shouldn’t have started with an antique, but I’m poor right now so I have to make do with what I have.

I’ve found if I leave the bottom vent closed and only open the door vent that the fire eventually completely goes out. I suspect it’s because my wood isn’t properly seasoned (it came from various sources). I’ll keep playing with it until I find the magic combination that lets me get a fire to generate heat for as long as possible.

I can’t find any sort of operating information for this stove—the closest I could find was a Round Oak, which I’m guessing is probably similar. I guess my biggest question is about how much wood I can safely put in it, but I suppose there may be too many variables to get a simple answer.

I appreciate the help. You guys are on the ball around here!


----------



## SpaceBus (Oct 8, 2019)

You will figure out how much wood you need per load as you get better at using the stove. If your wood is not seasoned then under fire air is probably all that will get it to burn in a stove. Ideally you want the least air possible while still having flames in the firebox.


----------



## bholler (Oct 8, 2019)

WoodBerner said:


> Allow me to vent about the vents: too many vents!
> 
> I’m new to this wood stove thing, and I’m sure I shouldn’t have started with an antique, but I’m poor right now so I have to make do with what I have.
> 
> ...


If there were direction it would tell you to use coal because it is designed to work with coal.  It was never mehant for sood and using sood will be frustrating


----------



## coaly (Oct 8, 2019)

bholler said:


> If there were direction it would tell you to use coal because it is designed to work with coal.  It was never mehant for sood and using sood will be frustrating


I second that !

Do you hear any sizzle from the wood? Notice and liquid boiling out the ends? Are the ends of logs solid, or cracked like wagon wheel spokes? These are signs of unseasoned wood. The cracks in ends are not a good indication, that shows shrinkage which is an indication of at least some drying. You really need a moisture meter to make sure it is under 20% or you're going to have problems.

Wood will burn very fast, you will have temp spikes, fast hot / cold cycles, and waste lots up the chimney. Hard on the stove and hard on you.

The only wood you should put in it is very small kindling, then sprinkle Anthracite Chestnut size over the top. As it catches, you cover the fire completely with coal to the top of the burn pot. Maintain blue flame on top of the coal bed. Shake down twice a day, remove ashes once a day, and top off with coal daily. It will go until you let it go out in the spring.
Once you do that, you will never go back to wood in it for sure.

Do you have electric resistance type baseboard? If so, coal is much cheaper. Figure $400 - $480 around here for coal for an entire season compared to the total electric bills all winter. Could not heat for 2 months with electric for that around here!


----------



## WoodBerner (Oct 8, 2019)

This time I added too much wood and it must have been properly seasoned. Once it caught, I closed every vent on the stove and the temperature  still went to over 625°.


----------



## fbelec (Oct 9, 2019)

625 is not a bad temp for a cast iron stove. but keep this in mind if you are burning wood that is not seasoned enough and you open the vent to slow the burn down the combo of fresh air in the pipe and chimney with the unseasoned wood will build creosote really fast and then you'll have a chimney fire.


----------



## coaly (Oct 9, 2019)

fbelec said:


> 625 is not a bad temp for a cast iron stove. but keep this in mind if you are burning wood that is not seasoned enough and you open the vent to slow the burn down the combo of fresh air in the pipe and chimney with the unseasoned wood will build creosote really fast and then you'll have a chimney fire.


His stove isn't cast iron.
It's a sheet metal barrel type stove with cast iron burn pot for coal.

I'm sure it isn't "air tight" if it didn't go out by closing down all air, so obviously it needs a stove pipe damper to slow the draft to be able to regulate a leaky stove.

To the original poster, a pipe damper slows velocity of rising gasses in the chimney. This decreases draft.
Draft is a measurement of rising gasses in the chimney flue which creates a *low pressure area in chimney, pipe and stove.* This allows atmospheric air pressure to *PUSH* air with oxygen into the stove. Reduce the draft, and you reduce the amount of air leaking into the stove. The chimney is not just to let smoke out. It is the engine that drives the stove and makes it work.
As I told you above, opening the dilution air damper inlet slows the draft for coal, but wood will use air from anywhere it can get it, so you need a manual damper in pipe to slow draft with wood. Try a bag of coal and your  problems will be over.

The incoming air under grate cools the grate as well, which is the part that wears out on your stove. Never leave ash build up to the point of blocking the air holes through grates!  That is the #1 mistake which ruins coal stoves.


----------



## begreen (Oct 9, 2019)

625º through the thin skin of the stove does not seem unusually high.


----------



## WoodBerner (Oct 9, 2019)

Everyone keeps recommending I burn coal, and I’m willing to try that as an experiment, but here’s the problem: I can’t find anywhere to buy coal here. I live in Fayetteville, AR. A search for “coal for sale” shows me two options: Tractor Supply, which sells a 40 lb bag of nut coal for $10 (including tax), or coalforsaleonline.com, which sells a ton for $1,200.  Those are my only options.

From what I’ve read, people are saying they go through about 50 lbs a day. Let’s assume I use 40 lbs because my house is small. That’s $300 a month, which is more than my highest cost for electric heat. Plus the cost and hassle of driving to the store, buying it, bringing it home in my car, etc.

Maybe I need a modern stove. But I don’t have one, and I can’t afford one right now, so its more helpful to discuss whether I can do anything to improve my wood burning experience.

Not trying to be grouchy, just trying to explain my situation. I really appreciate all of the help and information.


----------



## WoodBerner (Oct 9, 2019)

begreen said:


> 625º through the thin skin of the stove does not seem unusually high.



Some people are saying that since it’s not fully cast iron that I risk damaging the metal and ruining the stove. Do you agree?


----------



## begreen (Oct 9, 2019)

The stove looks to be in decent condition. With the nickel polished up it should sell for around $500 to the right person. That would put you very close to the cost of a modern stove like an Englander 13NC or Century S244..


----------



## begreen (Oct 9, 2019)

WoodBerner said:


> Some people are saying that since it’s not fully cast iron that I risk damaging the metal and ruining the stove. Do you agree?


If any part is glowing red then it is too hot, but these tin stoves stood up pretty well to the temps you are seeing.


----------



## WoodBerner (Oct 9, 2019)

In this thread, people say that their coal beds seem to burn between 1000-2000 degrees F: https://coalpail.com/coal-forum/viewtopic.php?f=67&t=488

Why would a wood fire burning cooler than that be dangerous to the stove?


----------



## begreen (Oct 9, 2019)

WoodBerner said:


> In this thread, people say that their coal beds seem to burn between 1000-2000 degrees F: https://coalpail.com/coal-forum/viewtopic.php?f=67&t=488
> 
> Why would a wood fire burning cooler than that be dangerous to the stove?


The coal bed is typically in a refractory, firebrick or cast iron chamber inside at the lower part of the stove. This protects the outer jacket. The surface temps you are seeing are not too high. Keep them under 750º and it should be fine.


----------



## coaly (Oct 9, 2019)

WoodBerner said:


> Everyone keeps recommending I burn coal, and I’m willing to try that as an experiment, but here’s the problem: I can’t find anywhere to buy coal here. I live in Fayetteville, AR. A search for “coal for sale” shows me two options: Tractor Supply, which sells a 40 lb bag of nut coal for $10 (including tax), or coalforsaleonline.com, which sells a ton for $1,200.  Those are my only options.
> 
> From what I’ve read, people are saying they go through about 50 lbs a day. Let’s assume I use 40 lbs because my house is small. That’s $300 a month, which is more than my highest cost for electric heat. Plus the cost and hassle of driving to the store, buying it, bringing it home in my car, etc.
> 
> ...



You don't need a modern stove, you need a wood stove.
I'm in the same position as you with acreage of woods, so I have to weigh the work factor taking lots of time for wood or buy coal and give myself a break. About every 3 years I go coal, since storms and dead trees have to be cleaned up anyway. I never cut live trees unless they are a problem. I do have a dedicated Hitzer coal stove with gravity hopper feed, and miss using the Kitchen Queen with oven using wood, so many times I'll fire the wood stove when baking and idle down the coal stove for a day or so. You "can" burn wood in any coal stove, just not efficiently. You can't burn coal in a wood stove. They are built differently for different fuel.

With that small stove you may only go through a little over a bag a week. I go through one coal hod a day with normal temps around 32*, two buckets a day in the single digits and below. Yours won't hold more than 1 bucket. (coal hod) Probably only a half a day.
5 weeks per 6 heating months (here) would be 30 weeks heating, so your cost at $10 / week, is more like  $300 for the entire season. That should be about right since I can burn $440 worth here a season in a much larger stove. (At least 3 times the grate area) January and February we don't go much above freezing with rare 0 degree nights.
If you try a bag, you will find out how long it will last and have a better estimate. "Nut" is Chestnut, which is the size you want.
I have heated 1800 sf. in NE PA. for many years, and two tons a year is average. A mild year we only used 1 ton, long cold winters 2 1/2. It can vary that much. That is our only heat source. We light it early November and let it go out late April. 20 years ago it was 100 a ton, couple years ago it was 220 a ton, a little more now. Coal follows diesel fuel prices because it take diesel to mine and haul it, but is the most stable priced fuel you can buy. For those of us that live near coal sources it's a no brainer, just like living near a pellet mill where that fuel is abundant.
It also needs to stay below 40*f for a 24 hour period to light and maintain a coal fire unless you have a very efficient insulated chimney.
There is a learning process to burn coal. Don't expect to go "one match" an entire season learning the first year. We only shake and empty ash in the morning, and shake and fill at night, but your smaller stove will need more attention than twice a day.

If you continue wood, depending on chimney, you will need a damper in the stove pipe to control draft. (very cheap) A pipe damper is not a stove control, it is a chimney control that _affects_ the stove. Used properly it will prolong your fires. Used improperly it will create creosote.

If you burn coal, you should have a barometric damper in the pipe to control draft. (not using the manual dilution damper on stove) Coal requires a much more controlled draft, so the barometric damper for coal use maintains a steady draft automatically, so it will keep going with a steady air flow up through coal as the weather and atmospheric pressure changes. They didn't have the more accurate barometric damper when that stove was built.

We don't have the specifics of your chimney, so we can only assume it is the same diameter as stove outlet, and hopefully has an insulated liner. Without the right chimney it's not going to heat your house efficiently no matter what you do.
*** Also depending on your liner, (if metal) you may or may not be able to use coal, since it must have a more corrosive resistant liner to burn coal. ***
For a modern stove you will also need the correct size and type chimney to make it work, we can't advise what to use or what you should get without knowing what your chimney is. The cost of a proper liner is more than the stove.  You need a stove to match the chimney, or line the chimney to match the stove.


----------



## coaly (Oct 9, 2019)

WoodBerner said:


> In this thread, people say that their coal beds seem to burn between 1000-2000 degrees F: https://coalpail.com/coal-forum/viewtopic.php?f=67&t=488
> 
> Why would a wood fire burning cooler than that be dangerous to the stove?


The coal bed also has LOTS of air coming up through the grate to keep it cool. Other wise the grates warp and melt. Coal uses tons of air compared to wood.

Coal heats the rest of the stove more evenly. It is a glowing mass, with small blue flames on top. Wood has very hot and cool cycles. The flame tips are all the way up to the top. (and out the stack) When starting with wood, your stack temp will be 300 -400 like a wood stove. Coal drops stack temp to 100 - 150. (these are surface temps, flue gas is about twice the surface temp) The stove will radiate about the same temp. Just much more even, steady heat with coal.


----------



## fbelec (Oct 9, 2019)

coaly i love reading your posts. i learn quite a bit each time. 
thanks
frank


----------



## coaly (Oct 10, 2019)

fbelec said:


> coaly i love reading your posts. i learn quite a bit each time.
> thanks
> frank


Thanks, I try to explain how things work as simple as possible so people know WHY they need to do what is necessary, not just remember what to do.  Something out of the ordinary is always going to happen, so if you know the basics and physics of what makes something work, you can operate it or know what to do to fix it.

It's easy in this case to suggest burning the correct fuel the stove was made for, but if they have an 8 X 8 common masonry chimney, two stories high, that small stove will never heat the chimney area to create enough draft to make the stove work properly AND create enough heat to radiate off it to heat the area they are trying to heat. Back when that stove was used, 3 of them could be heating the same chimney! You had to keep any cold stoves closed tight, but once more than one was going, you had some major draft to help get another going, then back them all off with so much draft. Many people have contacted me with big chimneys claiming they have great draft, but are connecting a small stove that won't seem to heat the indoor area they have. They don't realize a bigger chimney needs a bigger stove with lots of heat loss to have enough to radiate into the home. So they can get a larger stove and go through tons of fuel, or make the chimney right and magically their small stove works great!


----------



## WoodBerner (Oct 10, 2019)

I installed the stove using single wall pipe to the ceiling box, then insulated 6” pipe through the attic and out the roof, maintaining 2” clearance from all combustibles. There is no masonry involved.

I visited TractorSupply today and they said they have no coal available and no idea if and when they’ll have it back in stock. They don’t offer it for order either, so I guess there is no coal for me.


----------



## coaly (Oct 10, 2019)

You will certainly need a pipe damper to slow the draft having the proper size and insulated pipe.
Use a magnetic thermometer on the single wall pipe. That will read about 1/2 of actual flue gas temp. The object is to keep the chimney flue temp above 250* to the top. This is only when smoke is present. Over that is wasting fuel up the chimney. Below that allows water vapor from combustion to condense on flue walls which allows smoke particles to stick. This is creosote. 

Just as well they don’t have coal. Expect to replace  stainless chimney parts every few years burning coal. The top cap rots right off in a couple years. That is the price burning the cheapest fuel. It is even corrosive to masonry over time. They consider Class A “all fuel” chimney, but it doesn’t have the corrosion resistance of liners made for coal, or the cost.

I’d try the pipe damper about half closed once up to temp. You’ll find stove temps moderated and much more controllable. Fires will last longer, but still be short. A wood stove will carry a fire overnight. You burn on an inch of ash and it slows the fire so you have a pile of coals in the morning. You won’t do that burning on a coal grate.

Newer EPA stoves burn smoke at the top compared to burning wood with flames, completely different than older cheap stoves. But you can’t burn anything partially seasoned. Only premium fuel for them. You have the right chimney for a new or older stove.


----------



## bholler (Oct 10, 2019)

coaly said:


> You will certainly need a pipe damper to slow the draft having the proper size and insulated pipe.
> Use a magnetic thermometer on the single wall pipe. That will read about 1/2 of actual flue gas temp. The object is to keep the chimney flue temp above 250* to the top. This is only when smoke is present. Over that is wasting fuel up the chimney. Below that allows water vapor from combustion to condense on flue walls which allows smoke particles to stick. This is creosote.
> 
> Just as well they don’t have coal. Expect to replace  stainless chimney parts every few years burning coal. The top cap rots right off in a couple years. That is the price burning the cheapest fuel. It is even corrosive to masonry over time. They consider Class A “all fuel” chimney, but it doesn’t have the corrosion resistance of liners made for coal, or the cost.
> ...


There are plenty of class a chimney systems that are coal grade


----------

