Importance of Over Fire Air & Blue Flames

Importance of Over Fire Air & Blue Flames

PostBy: JRLearned On: Mon Nov 05, 2012 11:15 pm

I recently picked up a Jotul 507 to set alongside my cannon heater as an all day, 24-7 stove. It's fun to see the differences in the way each burns anthracite. Maybe that should be a separate topic, but my questions are about the Jotul and over-fire air. The Jotul has 3 air vents: the bottom damper for primary air under the grates, the middle damper in the door at level of combustion, and the top damper in the loading door above the coal bed. The top and middle dampers have never been opened, infact they are rusted shut/stuck. I've noticed when burning in the Jotul, there is a sulfer smell outside the house coming from the chimney. I've read here and there that a little over fire air will help burn off the gases that cause the smell. Is that true? Does anyone have some real world experience with airtight hand-fired stoves to share on this? Should I get that top damper open a little above the coal bed? I noticed when I open the top loading door, after a few seconds, blue flames ignite and start dancing on the coal bed. Door closed and the thing must be burning with no blue flames. Are the blue flames some important aspect to a burning coal? The coal burns well in the Jotul without the blue flames. It seems to idle at 400-500 degrees for 10-12 hour straight on a single load. Will it burn better with some over-fire air and the blue flames? Or will over-fire air cause the coal bed to burn more quickly or have other negative effects?
JRLearned
 
Stove/Furnace Make: Chubby Stove
Stove/Furnace Model: FrankenChubby

Re: Importance of Over Fire Air & Blue Flames

PostBy: freetown fred On: Mon Nov 05, 2012 11:41 pm

I rarely get blue flames unless I open up my bottom vents more then I normally like to--, but the the old Hitzer is surely cookin up a nice steady fire beneath. I would not suggest any over fire air. I'm sure some jotul people know more then me, but I am air-tight with hopper fed--I may sound silly, but I'm looking for heat, not cute lil dancin ladies ;)
freetown fred
 
Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut/Stove mix

Re: Importance of Over Fire Air & Blue Flames

PostBy: Lightning On: Tue Nov 06, 2012 1:17 am

Come on Fred, who doesn't like some hot lil blue dancin ladies :lol: I'll throw in my opinion on the whole thing, cuz I've wondered the same. Bear with me, there is a lot going on here... It seems to me that if the coal bed is under a particular temperature, there are no flames and any over the fire air will result in wasted heat going up the chimney, although you may need this heat to help support your draft. BUT, if it gets above a particular temperature, there is enough combustible gases coming off the top of the coal bed to support flames when air coming in over the fire is introduced (like you've noticed). There are a couple things that can happen at this point.

#1 - These gases, without any over the fire air will simply float up and out the chimney. (wasted potential heat)
#2 - These gases, without any over the fire air could build up in the fire box and flash. (puff back)
#3 - These gases, WITH just the right amount of over the fire air, will yield me a few more BTU's

Number Three is tricky.. Meaning too much over the fire air will net you lost heat going up the chimney (in the form of heated air) and at the same time, not enough over the fire air will also net you lost heat going up the chimney (in the form of unburnt combustible gases). SO in my opinion, the perfect case scenario is the right combination of under the fire air (primary) and over the fire air (secondary) and that these air feeds are completely independent of each other. Meaning, primary air can't bypass the coal bed and act like secondary air, which was a huge problem for me. This combination will change based on just how hot you are pushing the fire. This is based on my own thought and observation. I would love to hear some others' thoughts on this also! Results and opinions may vary, some side effects could be life threatening (probably not) or are just a lot of fun to watch (Fred) :lol:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

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Re: Importance of Over Fire Air & Blue Flames

PostBy: SMITTY On: Tue Nov 06, 2012 1:52 am

FOOOF!! :blowup:

:funny: Usually that happens when you don't see blue. Just happened to me again tonight ... and I had the ash door open! What a cloud that made. I'll have to review the camera footage on that one. :D
SMITTY
 
Stoker Coal Boiler: Patriot Coal - custom built by Jim Dorsey
Hand Fed Coal Stove: Harman Mark III (not currently in use)
Coal Size/Type: Rice / Blaschak anthracite
Other Heating: Oil fired Burnham boiler

Re: Importance of Over Fire Air & Blue Flames

PostBy: Lightning On: Tue Nov 06, 2012 2:18 am

Smitty :lol: please review rule number two:

#2 - These gases, without any over the fire air could build up in the fire box and flash. (puff back)

:roll:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

Re: Importance of Over Fire Air & Blue Flames

PostBy: NoSmoke On: Tue Nov 06, 2012 6:30 am

Lightning wrote:Come on Fred, who doesn't like some hot lil blue dancin ladies :lol:


You were one of those people that had the hots for Smurfett weren't you? :-) (Just teasing Brother, no offense meant).

I do NOT have a Jotol stove, but I do have an air tight stove that is hand fed with no secondary air. I find that when I reach the situation you get, if I crack the bottom damper a bit more, then it works out just fine with no smell of sulfur in the house and the blue flames return.
NoSmoke
 
Hand Fed Coal Boiler: New Yoker WC90
Hand Fed Coal Stove: Vogelzang Pot Bellied Stove
Coal Size/Type: Stove/Nut/Pea Anthracite
Other Heating: Munchkin LP Boiler (Back-up)

Re: Importance of Over Fire Air & Blue Flames

PostBy: freetown fred On: Tue Nov 06, 2012 8:01 am

Something I did forget to point out. If I kept the dancing blue ladies for any length of time, this old house would turn into a sauna in short order. Now this is just with MY Hitzer 50-93. Outstanding stove, outstanding draw. The old homestead stays at 72* consistantly. Some like it warmer, some cooler.
freetown fred
 
Hand Fed Coal Stove: HITZER 50-93
Coal Size/Type: BLASCHAK Nut/Stove mix

Re: Importance of Over Fire Air & Blue Flames

PostBy: SMITTY On: Tue Nov 06, 2012 9:55 am

Lightning wrote:Smitty ... please review rule number two:

#2 - These gases, without any over the fire air could build up in the fire box and flash. (puff back)


Well aware. :D ;)





The video(s), as promised. Nice and short. First one is real time, second one is slowed to 1/8th normal speed. The basement was dark when it happened, so it came out nice. :D
Attachments
Coal explosion, real time.wmv
Real time
(516.3 KiB) Viewed 277 times
Select:BBcode:
[nepafile=37678]Coal explosion, real time.wmv[/nepafile]
Coal explosion, slow motion.wmv
Slow mo
(1.96 MiB) Viewed 199 times
Select:BBcode:
[nepafile=37679]Coal explosion, slow motion.wmv[/nepafile]
SMITTY
 
Stoker Coal Boiler: Patriot Coal - custom built by Jim Dorsey
Hand Fed Coal Stove: Harman Mark III (not currently in use)
Coal Size/Type: Rice / Blaschak anthracite
Other Heating: Oil fired Burnham boiler

Re: Importance of Over Fire Air & Blue Flames

PostBy: fastcat On: Tue Nov 06, 2012 10:25 am

I have no over fire air but I have found as Fred said with the blue flames dancing there is more heat coming from the stove, so I have found that if I turn down the stat on the rear of the stove down some I can have the blue flames and still maintain my 72*. So I would also agree with Lightning that if you are not burning the gasses you are wasting good heat up the chimney, my lower vent is always open some and I always have blue flame after the fire settles out after loading and they continue throughout the 12 hour cycle.
fastcat
 
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Blaschak Nut/Stove Mix

Re: Importance of Over Fire Air & Blue Flames

PostBy: EarthWindandFire On: Tue Nov 06, 2012 12:07 pm

I think that the amount of over-fire air required is dictated by the air-tightness of your particular stove. If the stove is built tight, than you need to introduce air above the fire, if the stove is leaky, then you need to adjust your spinner accordingly.

For example, my Hitzer 75 was built as a basic shop heater and therefore is very leaky. Nothing is wrong with my stove, it was just not designed or built to air-tight tolerances. Each and every stove is different and each design has advantages and disadvantages. I would err on the side of adding over-fire air, especially on a tightly built stove.
EarthWindandFire
 
Hot Air Coal Stoker Furnace: Leisure Line Lil' Heater.
Hand Fed Coal Stove: Hitzer model 75.
Other Heating: Oil and Natural Gas.

Re: Importance of Over Fire Air & Blue Flames

PostBy: coalnewbie On: Tue Nov 06, 2012 12:39 pm

Well I am real old hand Jotul 507 owner with a whole 14 days experience. The first thing to do is suck all the info out of the old time 507 owners, freddy, the snowman and others. Then just blindly follow their advice as in time it will become obvious why they do what they do. Life is too short to learn everything yourself. So a rusted middle door vent is of no concern if you burn coal only. Do whatever it takes to free up that top dial and turn one and a half turns out. the snowman says so - so I do it. Search Jotul 507 and just suck up the info. I have learned only one thing so far, in my estimation this stove burns much better with stove and only use nut to start the thing. As fred says - it's not brain surgery so don't try and make it so. Use your spare mental capacity to work out why women so what they do. My lifes motto at my age is discover nothing, copy everything, drink beer and stay warm.
coalnewbie
 
Hot Air Coal Stoker Stove: LL AnthraKing 110K, Pocono110K,KStokr 90K, DVC
Hand Fed Coal Stove: Hitzer 50-93, Jotul 507
Baseburners & Antiques: Red Cross Invader 2
Coal Size/Type: Rice, Chestnut
Other Heating: Heating Oil CH, Toyotomi OM 22

Re: Importance of Over Fire Air & Blue Flames

PostBy: Rwalker On: Tue Nov 06, 2012 6:42 pm

I have the Hitzer 983 insert with double doors. It has sliding vents in the top, screw out vents on the doors, and the sliding vent on the ash door. It also has a manual sliding damper.

I open the damper the whole way, then I shake my grates hard until I fill the ash pan and get some red hot from each grate. After that I cover it with 2 small shovel loads and leave the ash door open to flare it up. Tons of blue flame. A few minutes later I add another layer. I continue until I am at the top of the fire bricks and there is blue flame dancing all over it. Then I shut the ash door completely and push the damper almost the whole way in and leave the vents slid open for a good 20-30 minutes. I then close them about half way, but never fully closed. If it seems to be slowing down, I will slide the vents open the whole way for a bit, then back them back down.

This has worked thus far, and I have a little bit of blue flame all day long, even when untouched for 15 hours there are still small blue flames in the back. I dont use the top vents or the screw vents on the door unless I am burning wood.

I re-loaded this morning at 5 am and right now there are still small blue flames.

Just my 2 cents.
Rwalker
 
Stove/Furnace Make: Hitzer
Stove/Furnace Model: 983

Re: Importance of Over Fire Air & Blue Flames

PostBy: tcalo On: Tue Nov 06, 2012 8:29 pm

Fred, I'm in the same boat as you. On low fire I rarely see blue flames across the coal bed. I make sure that I do get them after reload to be sure it is safe to close up the stove. I've had the stove turned up recently due to the low temps and I've been getting flames across the coal bed. The secondary air purges seem to help burn off the gases quicker. The stove usually has to be burning about 375* or higher for the coal bed to produce visible flames. May just be my stove. As long as you initially get the flames after reload I would say it's safe to close up the stove!
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Importance of Over Fire Air & Blue Flames

PostBy: JRLearned On: Fri Aug 09, 2013 10:52 pm

freetown fred wrote:I may sound silly, but I'm looking for heat, not cute lil dancin ladies ;)

Who doesn't like some hot dancin ladies?!?! :shock:
JRLearned
 
Stove/Furnace Make: Chubby Stove
Stove/Furnace Model: FrankenChubby

Re: Importance of Over Fire Air & Blue Flames

PostBy: Lightning On: Fri Aug 09, 2013 11:30 pm

I love the blue dancing ladies hahaha.

Oh uh lol I like the dancing blue ladies also :lol:
Lightning
 
Hand Fed Coal Furnace: Clayton 1537G
Coal Size/Type: Nut Size / White Ash

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