Question about over-the-fire air vents

Question about over-the-fire air vents

PostBy: UpStateMike On: Tue Nov 18, 2008 12:12 pm

I read something in another recent thread about coal should only have air coming from the bottom, and through it and not have air coming in from the top.

IF this is true, then please tell me why my stove Elmira Oval Cookstove) has a coal kit which includes a top vent that is added on for use with coal? The vent plate is on the front loading door.


http://www.heartlandapp.com/PDF/Manuals/Oval_Sweetheartman.pdf
This link is broken, either the page no longer exists or there is some other issue like a typo.


What would be the point of installing this vent? Is it just there to use to vent gasses from freshly loaded coat and you want to open the key plate?

Thoughts?

Thanks

Mike
UpStateMike
 
Stove/Furnace Make: Elmira Oval (in house)
Stove/Furnace Model: Round Oak d-18 (workshop)

Re: Question about top vents

PostBy: LsFarm On: Tue Nov 18, 2008 8:34 pm

When burning Bituminous coal, there a need for over-the-fire air to burn off the volitiles.. in some anthracite stoves [really airtight ones] there is a need to carefully burn off volitiles from fresh coal.. But for a long steady burn, you need air only from underneathe the fire.

Read the sticky note at the top of this forum about 'a minor explosion' it's about burning off the volitiles..

Greg L

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LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Question about top vents

PostBy: UpStateMike On: Thu Nov 20, 2008 1:08 pm

Thanks Greg. I think I understand the need for the over the fire venting for preventing the gasses from causing explosions, but do you keep this vent open all the time while burning, or just until the coals are glowing?
UpStateMike
 
Stove/Furnace Make: Elmira Oval (in house)
Stove/Furnace Model: Round Oak d-18 (workshop)

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Re: Question about top vents

PostBy: Dallas On: Thu Nov 20, 2008 3:26 pm

The over the fire vents can be and have been used for over night "damping down". With this vent open, some of the chimney draft is satisfied by over fire air, rather than air which is going through the fire. Another old time trick, was to "tip the lids", which was for the same purpose.
Dallas
 
Hand Fed Coal Stove: Modified Russo C-35
Other Heating: Oil Hot Air
Stove/Furnace Make: Russo
Stove/Furnace Model: Modified C-35

Re: Question about top vents

PostBy: LsFarm On: Thu Nov 20, 2008 3:48 pm

Hello UpstateMike.. you should leave the over the fire air vents closed except when fresh coal is loaded.. not all coal or coal stove instalations will create 'puff-backs' it depends on trapping the gasses, volume of air/gasses and chimney draw..

Leaving the over-fire air open to cure excess draft, or 'tipping the lids' in an old cookstove are bandaid techniques to deal with a too strong draft.. that is what Barometric dampers were designed for.. to limit excess draft to a managable, controlable level..

Have you installed a manometer in your instalation so you can see the actual draft?? It is much easier to figure out what is happening when you have some instruments to read.. instead of waiting to see the results of under or over draft, heat etc..

Take care,, Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Question about over-the-fire air vents

PostBy: matrix5089 On: Thu Nov 20, 2008 8:28 pm

Mike hows coal been burning in the elmyra? I keep my top vent closed all the time except when adding coal no problems so far.
matrix5089
 
Stove/Furnace Make: Elmira
Stove/Furnace Model: oval

Re: Question about over-the-fire air vents

PostBy: stelradCoal On: Thu Nov 20, 2008 11:20 pm

I have a Glenwood kitchen stove, it was my Grandma's actually, and now its burning away in my kitchen. The over the fire vents were to break the draft so you could keep the fire going for a long period. I don't have a baro on my stovepipe just an old style damper. Generally at night I close that damper completely and open the over the coal vent and have a nice fire still going in the morning. If I don't open the over the coal vent and leave it all night it usualy burns out.
A baro would probably work pretty well, but would probably annoy me flapping away in my kitchen. Good luck with the stove, their great for making soup on.
stelradCoal
 
Stove/Furnace Make: Stelrad 120k, Coal-o-Matic
Stove/Furnace Model: Glenwood Duplex Kitchen Range

Re: Question about over-the-fire air vents

PostBy: matrix5089 On: Sun Nov 23, 2008 6:30 pm

what temps are you guys getting on your kitchen stoves in the actual oven?
matrix5089
 
Stove/Furnace Make: Elmira
Stove/Furnace Model: oval

Re: Question about over-the-fire air vents

PostBy: UpStateMike On: Wed Nov 26, 2008 1:08 pm

Thanks for all the feedback. I think I'm on the right track now for using the over the fire damper. I can see how it would help to slow the burn overnight as opposed to monkeying around with the manual damper on the pipe.

I have been using the stove off and on, trying to figure things out as I go and some nights I'll burn wood and others coal. I do plan on eventually getting to all coal but there are the common bugs of learning a new stove that experience will be the best teacher. I still need to get a manometer to check the draft and probably next year I'll replace the manual damper with a baro.

Yesterday I had a nice woodstove going and when it got to the breaking into coals stage I shook it down a bit and then started in with the coal. Banked up over the next couple hours and at one point looked in on it to see the most wonderful blue flames raking across the igniting coal bed. I'm on late night baby feeding detail and was able to keep checking on it. At one point I had a great 400F temp (thermometer magnet on the rail near the key plate) and it settled down to about 360F when I was leaving for work.

Matrix, my wife has been using the oven a bit. The door thermometer is not accurate by any means so we go by the range top one for now until we get an inside the oven one. She's made some great cookies in there already and some muffins too. Make sure you turn the pan during baking because the firebox side is hotter.
UpStateMike
 
Stove/Furnace Make: Elmira Oval (in house)
Stove/Furnace Model: Round Oak d-18 (workshop)

Re: Question about over-the-fire air vents

PostBy: stelradCoal On: Tue Feb 03, 2009 7:51 am

I just noticed the question about the oven temp. :oops:

I generally run the stove with about a 300 oven temp. I have tested the door gauge against an inside gauge and its pretty close - as was noted above, the temp in the oven varies widely from side to side - so you have to turn things. I can get the temp up to 500 if need be. We don't use the oven too much, baked potatoes are great in there. When I dampen down the fire for the night the oven temp will be at about 100 or so in the morning. If its lower I know I will have very little fire left. but its pretty good for bringing a fire back so its not really a bother.
stelradCoal
 
Stove/Furnace Make: Stelrad 120k, Coal-o-Matic
Stove/Furnace Model: Glenwood Duplex Kitchen Range

Re: Question about over-the-fire air vents

PostBy: the snowman On: Tue Feb 03, 2009 11:36 am

My Jotul is very air tight. If I close the drafts on a fully loaded and hot burning coal bed; it will be out with no red coals within fifteen minutes and the only thing warm is the cast of the stove. The manual states that whether your burning Bituminous or Anthracite the over the fire draft should be open a little to create the secondary burn to burn off the volitiles. If I don't have the over the fire draft open I will get a large explosion of gases when opening the loading door and this is opening it very slow. I have my over the fire draft set at one and a half turns open. The unit can be run without it open, however, I don't like exploding gases and it seemed like a waste of btu having the unburned gases passing up the chimney. If I am going to be gone for a long peiod of time I will get the freshly loaded coal going and then close the over the fire draft and throttle back the draft on the ash door. For successful long burns at low draft settings the Jotul requires the over the fire draft setting to be closed. This is just my expeience with using the over the fire draft with my stove and setup. I believe that every stove and setup is unique to that person and is part of the learning curve to burning coal each peson must endure.

the snowman
the snowman
 
Hand Fed Coal Stove: Jotul 507
Coal Size/Type: Nut, Stove coal, Egg coal

Re: Question about over-the-fire air vents

PostBy: Pete69 On: Tue Feb 03, 2009 6:17 pm

The baker stoves also have over the fire draft controls, which CAN'T be closed completely.This allows for a small amount of secondary air for more complete combustion, and a more efficient burn, even with anthracite coal.
Pete69
 
Stove/Furnace Make: Baker/Vermont Castings/Chubby
Stove/Furnace Model: fireside /VigilantII/Chubby

Re: Question about over-the-fire air vents

PostBy: coalkirk On: Wed Feb 04, 2009 9:58 am

the snowman wrote:If I don't have the over the fire draft open I will get a large explosion of gases when opening the loading door and this is opening it very slow.


Isn't that exciting the first time it happens? WOW! It scared the crap out of me the first time. Talk about your blue ladies. Those are some angry blue ladies when the jump out like that. They say to try and leave alittle flame exposed when loading a hand fired stove with coal but it's alomost impossible with the Jotul as it is such a deep narrow fire box.
coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Question about over-the-fire air vents

PostBy: Str8liner On: Wed Feb 04, 2009 11:17 am

I am burning nut coal in my Brunco and it seems to like the overfire draft open about 1/4 inch.

Alot of variables from one system to the next will make everyone's results different.
Str8liner
 
Stove/Furnace Make: Brunco 190 Keystoker 250
Stove/Furnace Model: Keystoker 250

Re: Question about over-the-fire air vents

PostBy: Joe in NH On: Wed Feb 04, 2009 8:52 pm

I was having quite a time earlier this season learning to operate my Harman SF260 boiler. I was loading it like my smaller coal stoves where the occasional little puff when opening the door was the extent of any coal gas issue. The gas explosions in the Harman were blowing the chimney clean out door wide open as well as doing a job on the barometric damper. It was certainly getting my attention. I learned on this forum that the key to controlling the build up of coal gas in the firebox was opening the over fire draft spinners on the loading door. Since I have been opening the spinners one complete turn on each, I have not had another gas explosion. OK, there was that time that I forgot to open the spinners and the clean out door was open... this whooshing noise ... lots of ashes. I always close the over fire draft once the fire is strong and the blue dancers are performing. Joe
Joe in NH
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Trident SF 260 Boiler

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