First fire of the season in my Jotul #8

[spirilis]

It's been in the 50's, rainy and windy all day with no sunlight so the house was a tad chilly (71F is cold by my wife's standard--TRUST ME). This gave me a great opportunity to start our first fire :D

Some background-
The house I bought last year included 2 woodstoves, a Jotul #8 downstairs (pre-EPA non-catalytic, with the draft wheel air control, can also burn coal with the proper grates) and a Defiant II (1980) upstairs. The chimney is one of those dreaded massive 12x12's with both devices venting into the same flue liner, i.e. code violating. Flue length is about 20ft for the Jotul and 10ft for the Defiant.

I haven't lined it yet b/c I don't want to give up one or the other stove just yet, but for now I've blocked off the Defiant's thimble as it's the bigger stove and when we used it last winter, it would roast us out of the house in a hurry
The Jotul was a neat stove b/c it has glass in the door (the Defiant does not) so we could see the fire. However usually when I fired it up with pallet wood or even with woodbrickfuel (ala BioBricks), the glass would darken or go completely black along with clouds of smoke billowing over the lawn. Moreso with pallets than with the woodbrickfuel.

Fast forward to this summer, I did a total R&R on the Jotul including new gaskets for the stovetop and door and new stovepipes and fully vacuumed/scrubbed ashes out of the firebox and outside the steel burn plates inside.

After doing all that cleanup work, with the first fire I gotta say the stove performs *much* much better than it did last year. The glass hasn't darkened much at all (I would say it hasn't darkened at *all* except I see a slight tint when I open up the door and look through the inside of the door glass back into the room) and the flames became lively almost 5min after ignition. The flames have stayed lively the entire burn so far (maybe ~45min into it) and while there is some smoke coming from the chimney, it's really not much. I think the key here, besides the gaskets, is the fact that secondary air can now make it into the firebox reliably since I removed the ash and crud that collected behind the steel burn plates (which is where secondary air comes into the firebox; through the lower half of the draft wheel, under the firebox, up around the side steel plates and into the upper firebox). I think that may have contributed to its poor performance last year by causing the draft to be satisfied by primary air more than secondary air, thus rushing the pyrolysis of the wood and production of smoke.

Stovetop temp is in the mid-to-low 400's and not climbing much beyond that, but I did only use a 5-brick fire which is frankly the minimum I've found works for these stoves (both the Jotul and the Defiant). A 6- or 8- brick fire usually gives me those 600-700F temps. Consider each brick is 2lb, I only have 10lb of wood in there right now.

All in all, this is a lesson that stoves really *do* work much better when they're clean and sealed up properly. The fire is beautiful and while I took some pics I'm too lazy to upload them right now :D

 

[spirilis]

Looks like it's making its way into the mid-to-upper 400's/lower 500's now on the stovetop. Still a very clean, controlled looking flame coming off the mass.

 

[spirilis]

and now in the upper 500's/lower 600's... took a little while but yep, it got there!

Still a beautiful flame, now streaming straight up a little more through the center (some of the bricks expanded and the burning coals (coal-dust?) are in the middle of the teepee mass, with a gap in the middle so everything's burning from the middle)

 

[BrotherBart]

You are having entirely too much fun. :smirk:

 

[spirilis]

You are having entirely too much fun. :smirk:

:D that's right. Firebox is now much darker, with soft flames streaming up around the firemass, air turned down a bit and stovetop sitting at ~570 on the left side, and ~680 on the right side... flames mostly favoring the right side. Odd how that works.

 

[spirilis]

I let it burn down to a pile of chunky soft glowing charcoal-dust embers, raked them in a pile near the primary air inlet, then reloaded with 5 woodbricks stacked short-end facing the pile, so the wood bricks burn cigar-style, then a small slat of pallet wood on top. It lit in short order with brilliant flames, turned the air down a bit, wedged a small piece of crumpled aluminum foil in the primary air inlet so the primary air is restricted more than the secondary... stovetop ~700-750F, primary air very choked but the firebox is full of gorgeous yellow flames creeping out from little gaps between the glowing wood brick ember bed below. Flames in the perimeter of the firebox are almost ghost-like. First load in the basement stove only brought the upstairs tstat from 71F to 72F, but this second load has already kicked it up to 75F within 30min so I guess the basement is hot enough now the upstairs is warming.

Gotta love wood burning!

 

[spirilis]

stovetop temps dropped back to ~600-650 after I turned the air down, upstairs tstat up to 77F now ... not bad! will let it burn out and have the heat pump at 75F to catch it if the temp falls upstairs.

 

[EddyKilowatt]

Hi, another spin-wheel Model 8 owner here. We might be the only two here... I think these stoves go back to the early '80s. Amazingly, it still seems possible to get spare parts for them.

My wife found ours at an estate sale, liked the look (ivory), sent me a cellphone picture with a winsome "can I keep it... please?" message. I was proud enough that she bargained them down to half their asking price that I decided to hook it up and see what it would do. What it's been doing is heating our 1800 sf for the past two winters, quite well.

The window on ours stays surprisingly clean, too, despite the lack of that newfangled airwash. About as clean as the window on the more modern Avalon that we used to have. I feel that a clean window is more due to A) burning clean wood, and especially B) burning above the self-cleaning temperature (750F or so), than it is to airwash or other design features.

I am interested in the idea that the air that goes under and around the firebox is intended for secondary combustion. Do you know if Jotul actually claimed that was the case? From your description of ghost-like flames around the perimeter of the firebox, it sounds like that's what was happening. Have you seen secondary flames on a modern stove with air-inlet tubes above the fire, and were your flames similar?

I had figured the air around the firebox was mainly for cooling of the firebox burn plates. I figured that, because I actually installed insulation (leftover ceramic wool liner wrap) behind those plates on my stove. I felt that my firebox wasn't geting hot enough, or rather, I wanted it to get good and hot (clean burn) with a smaller fire. I did get a hotter fire. However, after two winters, I also got a bunch of fine hairline cracks in my rear burn plate, which I blame on my aftermarket insulation job. So before this season starts, I'm going to be replacing that plate and removing the insulation.

I'll keep a careful eye on the fire this Fall and see if I see any signs of secondary burn around the upper perimeter of the firebox -- maybe I'll try that ball-of-tinfoil trick to damp down the primary air a little. It would certainly be cool (hot?) to get a secondary burn in this stove; lack of secondary is pretty much its only shortcoming in my opinion.

You might be interested in the thermal-infrared pictures I took of the Jotul 8 firing up last winter... I think this link will take you to the thread, if not, search in the Picture forum:

We Have Ignition

.
.
Eddy

 

[spirilis]

OH wow, very cool! I don't have the original Jotul documentation for the stove (it came with the house I bought in May '09...) and mine was built in 1984. I just kinda assumed the air was there for secondary combustion since it injects itself into the upper firebox, near the baffle. I do know that when it gets roaring one could probably assume it continues secondary combustion up near the baffle and in the fluepipe, as my fluepipe gets VERY hot--tested last night the fluepipe (single-wall, with a 90deg elbow) was around 600+F for the first 2 feet and 500 beyond that. My VC Defiant upstairs, when I open it up and see flames are licking around the baffle and well into the fluepipe, show those same temps at the exterior of the stovepipe so I assume 500+ single-wall fluepipe exterior temps imply the presence of flames inside the pipe. The original owners had a key damper on the horizontal run of the stovepipe but I removed that last year and it drafted much better, bought all new stovepipe this year and didn't bother putting one in. I'm happy with the performance without one.

I've seen pics of modern burn-tube stoves and no, it's not really like that--partly because the secondary air comes in through the sides and the stock baffle doesn't really "baffle" all that much (it would probably do a better job of extracting heat if mine was rear-exit, but mine is top exit). I'd imagine the baffle in its current position acts as a good surface for providing turbulence of the gases to incite secondary combustion but for the most part the extra heat produced in that area goes out the fluepipe. If I could change my configuration I'd have the fluepipe go up another 2 feet before entering the chimney but alas, my thimble is where it is However, I did see a lot more flame in the corner areas of the firebox after I did R&R on it this summer, certainly moreso than I ever saw last winter. Whereas last winter under low-air conditions I wouldn't see much going on at the edges of the firebox, this fall I see more activity there--some mildly bluish/white (but still partly yellow) flames around the upper edge of the burn plates at lower air.

The one thing that will gunk up my glass without fail is new wood placed too close to the log retainer, or the use of pallet wood in any major capacity (more than 1 or 2 slats or a small section of the stringer). The woodbrickfuel I burn keeps it almost perfectly clean unless I pull a partly-unburned portion of it close to the log retainer/stove glass.
As for the insulation and the burn plates--what I did last year (greatly improved flames although ran through wood very fast) was to put half-thickness Firebricks inside, standing 2 on long end at the back and 2 on short end on each side. I don't have them in there right now but when the temps drop again I might give it a run with those back in place and see how it performs. I never noticed any cracks in the burn plates when I used them, probably because my burn plates were kept cooler by the firebricks (it does reduce firebox capacity a bit though).

Looking at your pics--You have rear exit, lucky I see the hotspot is right there at the front part of the baffle above the stove glass. In my stove it's a short distance from there to the flue exit but that is usually the hottest part of the stove, judging by observations with my IR thermometer. I totally wish I had one of those IR imaging cameras

I noticed these things claim to run on Coal fuel too... I've never touched coal before (and generally don't like the fossil-fuel stigma) but part of me wants to try it for kicks. The "Coal Kit #8" on woodmanspartsplus.com has some "fire bars" (I am guessing they sit between the V-shaped slots in the log retainer and rest on the shelf in the back burn plate?) but the dimensions they list on the website don't sound right to me. It says 8.5 inches long but I measured that distance and it varies from 11-12.5 inches. Kinda wish I knew someone who bought one of these brand new back in the day or a Jotul reference that could describe them in greater detail. Would love to see an original manual for this 1st gen model.
I did figure out how to "shake the grate" which is required for coal burning--Open the air intake all the way, stick a suitably curved piece of metal (my fireplace poker works fine if I twist and wiggle it in there) into the bottom slot ("secondary air" intake) and shake the whole bottom burn plate up & down. Since the log retainer rests at the front of the bottom burn plate it'll shake it up & down, and if the coal firebars lay on those it'll effectively shake the coal grate. Might be helpful to do this with wood too if you want to shake down the coals/settle the splits... Just a thought.

PS- I've played with damping down the primary air w/ foil a bit, I dunno but I don't see much of a difference. Who knows though--if I damp down the primary air far enough the fire starts to look anemic, but seeing as secondary air only makes it into the firebox (mostly) above the viewable area for all I know it's doing its job as expected, I just can't see it b/c it's all above the baffle and in the stovepipe. I should do a temperature comparison of the stovepipe ~6in above the stove when I do that.

 

[spirilis]

Did a modification to my Jotul #8 today after pondering about it a while. Seeing EddyKilowatt's thermal imaging pics of his #8, I noticed the most heat is concentrated around the front center of the unit, and his is rear-vented. Considering that my typical load of wood (6 wood briquettes) puts out hideous amounts of heat upstairs in the Defiant which is rear-vented and gets a very hot stovetop, while the Jotul being top-vented doesn't have much opportunity to heat the stovetop beyond what hits the edges of the top before it enters the flue exit, I thought it'd be worth a try to convert the Jotul #8 to a rear-vented stove.

It already has the hardware built in to reverse the flue collar--you have to unbolt the retainer for the cover plate on the rear, unbolt the flue collar on the front, then reinstall them in the opposite locations.

So I got a 7" single-wall tee, 7"-to-6" reducer, used my existing 6" elbow and cut a custom-length piece of 6" single wall to complete the setup. Had to pull the stove forward about 4-5" but it still has a good amount of hearth in front. Completed it this morning, gave it a quick fire from a supercedar to warm things up and pre-cure the furnace cement, fired up a typical load of wood about an hour ago, and right now I'm seeing ~680-750F stovetop temps with flue pipe temps ranging from 470F on the tee to 370F at the entrance to the thimble. Air is open somewhere between 1/2 and 2/3rds, excellent flames in the firebox and the downstairs room is hideously hot right now. This is an improvement in flue pipe temps as previously with the top-vent the flue temps right at the collar would sit around 600-750F and drop down to the 500's or maybe 400's by the point where it enters the thimble when the stove's running full bore.

There is plenty of wood left in the firebox to burn and I feel this experiment has proven fruitful as it seems the stove's giving off a lot more heat (hitting >700F stovetop temps so soon) while there still remains a fairly substantial amount of wood in the firebox. Draft seemed a little sluggish at first although there were no backdrafts at all, and I think some of the joints could use a furnace cement coating on the outside (most of them I cemented on the inside before joining together) to seal things up a little better.

 

[BrotherBart]

Sounds like success. I bet there is a lot less smoke too.

 

[spirilis]

Hey check this out, EddyKilowatt might like this... A chimney sweep up in Maine got back to me via email with a copy of the original manual for my Jotul #8 spin-draft version.
I uploaded it here: # 8 Spin Draft

He talked to a Jotul tech and they said they didn't think there was a coal burning insert kit for that stove, but he's doing some more research. The door clearly says wood or coal fuel only.

edit: With testing info from 1986 in there, I'm betting that's not the *real* original manual, but it provides more info on the older spin-draft stoves than the one you usually find on Jotul's site and circulating around the 'net.

 

[spirilis]

Also a little gem from that PDF -- Basic model 8's can be converted to 8C (catalytic) by replacing the flue outlet and housing. Huh!

Not that I can find any 8C parts though... :D

 

[begreen]

I think there was a post that the first cat attempt wasn't too successful. Best to enjoy that sweet stove as it is.

 

[spirilis]

Well yesterday was my first fire of the 2011-2012 season in the Jotul 8. The nagging concern I have had the past 2 years I've owned this place is what to do with the hideous 2-stoves-1-hideously-oversized-flue situation, and the various factors come together to make it quite a pain. The cheapest, most ideal solution (cosmetically and complexity-wise) hinges on the idea that our Jotul 8 downstairs can heat the whole house, which I haven't ever seen to be true in the past even loading the stove to its gills with woodbrickfuel. However, I never really tried it with the larger (~7-8lb/brick) Eco Energy Fuel blocks I bought midway through last season, and I'm giving it a try this weekend. It seems to be the magic ticket; closest thing to 12hr burn times, in that there are still embers burning and keeping the inside of the stove hot (outside just warm to the touch) after ~14-16hrs or so.

The trick is to use 2 woodbrickfuel (2lb/block) blocks leaning against each other, with a quarter supercedar underneath them, with two eco-energy fuel blocks flanking them so the flames shooting out the side of the teepee ignite the fuel blocks (and together create a confined central "inferno" to really get things moving). I put a 3rd one overtop and hit the teepee + whatever paper I put in there to help ignite the supercedar with a propane torch. That's another nice addition to this season; I now have a plumbing torch (bought for starting my Big Green Egg charcoal smoker/grill, but it's so much nicer than using paper or squirting gel firestarter and using a combination of a BIC lighter and a prayer... lol). I like to scorch some of the wood (within the path of the initial flames) before igniting the supercedar to just get it prepped so the stove warms up faster. Seems to work.

I'm estimating 90 days of solid 2 fires/day and I think that's pretty fair for this climate, those eco-energy fuel blocks come about 90pkgs per skid at 3 blocks/pkg, so I'd need about 2 skids of that with 18 pkgs of woodbrickfuel (50 pkgs/skid, so that's just over 1/3 ton and I do have that much or more still in the garage from last season). Looks like I should go buy some eco-energy fuel blocks if the local dealer has 'em in stock.

Seeing if I can heat the whole house by the downstairs stove means I could think of other options in a year or 2, like getting rid of the Defiant upstairs and having the chimney lined for better draft (though it is adequate right now for the Jotul with a 20ft flue length), and/or getting an EPA certified stove, or maybe even going to the dark side and getting an Anthracite coal stove... the fuel's definitely cheaper around here than those compressed sawdust bricks. Having the hearth upstairs clear would be nice for saving room in the living room, my wife likes the idea of putting the TV/entertainment stuff there anyhow.

 

[spirilis]

Well looks like the prospect of getting a Coal kit for the Jotul 8 is shot; parts are truly no longer available. But I do have a PDF of the coal kit with a diagram; quite an interesting contraption they made! It turned the stove into a top-loader apparently, with a hopper right below. The "fire bars" listed on Woodmanspartsplus.com are the short fire grate bars listed in the diagram; probably a wearable item so they carry it. But not the whole kit unfortunately. Would be fun to find one used... doubt I'll have any luck.

PDF - #8 Coal Kit

edit: The dealer said it didn't turn it into a top loader, I must've been reading the diagram wrong. Still a front-loader, which would've been a huge pain to load through the door with that tall hopper...

 

[spirilis]

Also major props to Mazzeo's Chimney & Stove in West Rockport, ME for tracking this down for me.

 

[spirilis]

Huh from that PDF's 1st page I noticed the 2 holes in the flue outlet are supposedly suitable for a pipe damper; makes sense, mine came with just bolts but I can see where a pipe damper would be just as good. It'd have to be a 7" one though. I might do that... I was thinking of trying a pipe damper again to see if it'd help get better burn times out of this old stove. One advantage of putting the damper there is it's very easy to get to; with a stone cold stove I just lift off the top cover, lift the baffle and voila, instant access to the flue outlet.

Although hmm... looking at the way they orient the damper, I will have to remove and reinstall the flue outlet 90 degrees rotated to what I have now; the holes are currently oriented on the left & right, but with a damper in that orientation along with the baffle the way it is, I'd imagine the damper will restrict the draft even in the fully-opened position, so it'll have to go the way they show it. Not gonna mess with that until I redo the stovepipe setup with 22ga. steel, something I was planning on doing anyway in case I wanted to keep the stove.

 

[spirilis]

Made a little modification to the stove recently. I noticed that the baffle leaves a gap in the rear corners that allows flue gases from the rear of the wood mass to take a shortcut over the baffle and out the flue exit when rear-vented. Decided to stuff some crumpled aluminum foil in those gaps. Also plugged up the little hole in the lower baffle (which points directly at the flue exit) with a small wad of foil. It's held up through 2 fires so far so I guess it's ok. If not, thin firebrick should fit over those gaps and the small hole probably isn't a big issue.

In either case, the stove burns much better; only downside is more smoke spills out the door when opened, but I can deal with that. Now all the flue gases must come to the front of the stove to make it over the baffle; this is just like most modern EPA stoves, if I'm not mistaken. The flames are much stronger and I see a greater percentage of blue flame coming off the wood, especially from the piece on top that's sitting just under the baffle; the edges of that wood block have blue flames streaming off of them throughout the width of the block, and all of that flame is hitting the baffle, going up to the front of the stove, over the baffle, under the stovetop and all the way back to the flue exit before leaving. I can keep reliable secondaries going with the draft closed off a bit further too. And it's only ~55F outside, so the draft shouldn't be all that good yet (not to mention I'm venting into a 13x13" 20' tall flue). I'm confident this modification will be a good one. Glass is cleaner too!

 

[spirilis]

wow, haha, the upper fuel block swelled more in the top than the bottom and it's leaning in the general direction of the window (but not touching), so much of the flue gas passes between it and the window. the upper 1/3rd of the window reads around 850F right now. hot damn (stovetop around 600-650, down from 750 earlier... lol)
that Jotul sure does burn hot, and I can't really see any smoke coming out of the chimney, though I could smell a faint whiff of the oak from the deck on the east side of the house (chimney's on the west side).

 

[spirilis]

chit well, walking away with the air draft fully open for an hour after starting it... resulted in 850F across most of the round griddle top and certain spots of the window registered 920F. that was hot. the ceiling above the stove was around 140F...

closed air draft to 1/2, it cooled down quickly, now in the lower 700's and the ceiling quickly cooled to around ~120-130F.

 

[begreen]

Don't do that! DDT. Get in the habit of setting a timer to alert yourself if easily distracted.

 

[spirilis]

Well now that I'm paying more attention to the stove and it's getting colder out (first snow of the season today, down in the lower 30's outside) I'm learning a lot about this new wood block "formation" I'm using. That is 2 eco-energy fuel blocks flanking the center of the firebox, 2 woodbrickfuel leaning against one another in the gap, and a 3rd eco-energy fuel block laying transverse on top of the woodbrickfuel, supercedar in between the woodbrickfuel, although the primary air intake port is directly facing the butt-end of one woodbrickfuel so I can't get to the supercedar directly, thus I typically use firestarter gel or newspaper to make it easier to ignite it

The larger (~7-8lb) eco-energy fuel blocks make great endurance fuel, but I've found the problem with the formation is once the smaller (2lb) WoodBrickFuel bricks burn out, it's left with a huge cavity in the bottom center of the firebox where the red burning charcoal surfaces of the eco-energy fuel blocks aren't close enough to really keep things hot enough to burn the rest of themselves clean (since the blocks are still in coherent block-like form and the center of those blocks still have tan unpyrolized wood sawdust, as I usually find when I whack it with a poker), so I guess at some point they smolder with a dark red firebox.
However, this morning I found the perfect use for that cavity--just stick another WoodBrickFuel inside. Only 1 needed, it quickly bursts into flame and reheats the stove back to ~650-700F while the remaining eco-energy fuel blocks slowly burn away merrily. I've been fiddling with setting the rotary air damper to ~3/4 open, then restricting the primary air a bit further (with a piece of crumpled foil) to tame the flames a bit while letting it burn cleanly. Seems to work. That tends to burn out the woodbrickfuel slower and keeps the stovetop in the upper 500's instead of the 700's Although once the flames in the periphery of the firebox die down, it makes less sense to provide secondary air (which washes the sides of the firebox) so at that point I pull out the foil piece and just close down the draft further to reduce firebox cooling from the secondary air.

 

[spirilis]

More playing. This time, adding thin dense firebrick sitting on top of the baffle to narrow the space between the baffle and top casting, hoping to improve heat extraction (force flue gasses closer to the casting; the stock gap between the baffle and stovetop is pretty big). Not gonna have a proper test of it tonight b/c I'm doing a short fire (managed to split an eco-energy fuel block in half using an axe and 4lb sledge for assistance, add 2 woodbrickfuel and you got the perfect "short fire") but some other day when it's cloudy and cold I'll light one up. So far this short fire is drafting well, so I don't think I'm restricting things too much here.

The measure, once I do a full-size fire, will be to see if the stovetop continues to reach ~700-750F at 3/4 air setting but the flue surface temp goes below the typical ~320-380F I normally see when it's running that hot. I'm hoping it'll dip into the upper 200's under those conditions but we'll just have to see. Oh and I shouldn't be able to see the smoke much from the top of the chimney, which typically I can't with this stove... it burns pretty clean for a pre-EPA.

 

[spirilis]

Hmm, well into the short fire the stovetop is ~520F, flue temp is ~250F, the very top of the front casting above the door is around 600F, I can't remember if that's typical or not though. One thing I have noticed is the stovetop temp drops in a noticeable gradient between the front of the stovetop and rear; the firebricks are arranged long-side left/right (and only 2 of them), so they don't go far back and the baffle slopes down pretty fast behind where the firebricks are located. Positioning them with the long-side front/back (and adding 1-2 more) might be the better bet b/c I bet all I'm doing with the current modification is creating a greater hotspot at the front of the stove. Gotta spread that hotspot out over the whole stovetop.