First fire of the season in my Jotul #8

[spirilis]

Surprisingly that short fire held some coals all the way till 5AM... stovetop was 93F, but upon using the ash rake I uncovered the remainder of the split eco-energy fuel block underneath the ash, glowing brightly red. Loaded another short fire with a supercedar overtop those coals, but not before quickly removing the stovetop and turning the firebricks front/back and adding 2 more. The new fire came right up, and one thing I'm noticing is while the temperature gradient still exists the flue temp is noticeably lower than the peak stovetop temp during startup; that rarely used to happen, the stovetop would be a consistent ~150F around the center while the stovepipe going into the chimney was also ~150F during startup (and the two would stay in step until 300+ F stovetop temps), now it's more like ~250F stovetop with ~180F flue pipe.

 

[spirilis]

Doing a big fire tonight. I'd say my firebricks are doing something alright. 15 minutes from ignition, front of the stovetop is 400F, back of stovetop ~280-300F, flue exit 230F, top of front casting above door is 500F. Wow! Much improved fluepipe temps. Not dumping so much heat out the chimney.

 

[spirilis]

Front of stovetop 670F, rear of stovetop 480F, flue pipe going into thimble 319F, top of front casting ~790F. That might be the downside... getting a LITTLE too hot on the top front of the stove. Turned the draft down to ~2/3 and it stabilized a bit. Glass is quite clean, flames look healthy, lots of blue and not too much bright yellow (but some, yellow and orange).

Still, larger delta between stovetop and the flue pipe going into the thimble.

 

[spirilis]

next reading:

680F front stovetop, 540F towards the back of the stovetop, 790F above door (that's stable, good), 309F flue pipe going into thimble.
~10 minutes after that:
~680-700F front stovetop, 580F towards the back, 325F flue pipe, 760F above door, noticing the upper sides getting warm too; 660F on the left side, 540F on the right side, and I've had a box fan hitting the right side for the past 10 minutes so that might explain the discrepancy between the sides. Glass is gunking up a tad, just some caramel haze in the upper right & left corners of the glass, not too bad though. I'm digging this setup. Should get more heat out of my uber expensive firewood... lol

 

[spirilis]

Sure does seem like I'm getting 600+F temps on the stovetop longer now... flue pipe 285F, and it's been around 1.5hr since my last update. Not too many flames in the firebox except in the sides where the larger fuel blocks are less burned out, the center is just a big red charcoal inferno. Got the draft set between 1/2 and 2/3. Very hot air coming up out the basement stairwell. I like it.

 

[spirilis]

And then there's the little fact of how the place is 3F above the heat pump's set temperature, 9-10 hours after ignition... with enough coals to keep the stovetop at 170F while the fluepipe is 120F. Wow. Definitely much better heat extraction!
Granted the outside temp is 39F, not 28-33F like it's been the past few nights, but still...

 

[spirilis]

I'm starting to gain more appreciation for the "quick kindling fire to establish a coalbed, then reload" technique. Problem is it's hard to do that with the compressed sawdust bricks when they don't coal up very well, but tonight I tried a hot fire with 4 woodbrickfuel + 3 slats of pallet wood and that made a hot vigorous fire that warmed us up, but left a healthy coalbed after 3 hours on which I've reloaded with only the Eco Energy fuel blocks. Those have established a healthy burn sitting on top of the coalbed, and what's more they're mostly blue flames, and the top of the fuel blocks have established a lazy blue "secondary" flame pattern from the secondary air the Jotul 8 has washing up around its firebox side liners/baffles. But the stovetop is only ~550F, not raging 720+ like usual when I start & load it with a full load of sawdust bricks. I'm able to position the fuel blocks closer together to partially restrict the amount of air passing through the mass, and hopefully that'll maintain a cleaner burn for longer too (with my normal config once the woodbrickfuel in the center burn through all the way, it leaves a rather large cavity in the middle that's too spacey to keep a clean burn going).

 

[spirilis]

Another "put fuel blocks on top of a coalbed" fire tonight... The fuel blocks do need more air, like my dealer said, when you're burning them alone with a coalbed, and they don't get quite as hot which is fine by me... longer burn times...
But they produce such marvelously pretty blue flames and fill up the space below the baffle with a stream of blue/bluish-yellow secondaries.

 

[Charlie500e]

Great info in here! I too have a Jotul 8 with draft wheel. Was in my detached garage when I bought my house about 10 years ago. Relocated it to a Catskill ski cottage a few years ago. I dont get to enjoy it much since I rent out the place but My current tenant is loving it!

 

[spirilis]

Good deal! It is a gem of an older woodstove, gorgeous castings and a real workhorse to boot. I'm happy with the modifications I've made to it (switching to rear-vent, plugging gaps in the rear corners of the baffle with foil and lining up 4 thin firebricks on top of the baffle to coax the flue gasses to spread out & touch the stovetop more) and my wife and I have made it a nightly ritual to go downstairs and bask in the sauna.

My 5 month old daughter loves it too; she likes babbling/talking to the fire in baby-speak. LOL

 

[webbie]

I love that stove! We were one of the first dealers - like the day it came out! I was quite astute (can't you tell?) about what makes a good wood stove design (SIMPLE), and remember seeing the wooden model of that bear at the tradeshow....this must have been 1982 or 1983 (guess).

We liked everything about it - from the packaging to the way it easily came apart for hauling into a house. This was a couple years before our shop sold Vermont Castings....and we went right up against their similar model (Resolute) and sold the chit out of the #8.

Yes, that baby put a smile on my face and $$ into the corporate bank account. I have to place it among my top 5 in all those years!

 

[Charlie500e]

Good stuff! When I brought it upstate I stopped in a stove dealer to pick up some rope gasket. They felt it was in very good shape and probably wasn't used too much. Kinda wish it was in my primary residence but I'll settle for my pellet stove.

 

[spirilis]

Found the best way to lay out those large 8lb Eco Energy Fuel Blocks on the reload. Just 2 of them needed, I stack them vertically leaning against the back/baffle in an open teepee formation so it's widest at the bottom and the blocks are about ~1-2" apart at the top.

I rake the embers into a pile in the front with most in the middle beforehand, place the big blocks, close the door and open the draft--after a few minutes once the fuel blocks warm up, the bottom and front ignites and when the center ignites the flames lick up the teepee and char/ignite the rest of the block. Massive column of hell shooting right up into the baffle!
Since the tops of the blocks sit so close to the baffle, and the flames shooting up the center of the teepee help ignite the tops, there are lively secondaries in the upper firebox and the stove gets up to proper temperature (currently 620F front center stovetop, 290F fluepipe@thimble at ~2/3 draft open). The backsides of the blocks (facing the side liners/castings) usually get hot enough to form ghost-flames too. Best of all, can't see a lick of smoke coming out of the chimney.

Also thinking Simpson DuraLiner rigid pipe is the best option for me. Gonna have some more cashflow coming in this spring, thinking of putting in the liner before next fall.

 

[spirilis]

Doing a variation of the 2-block vertical fire, but this time with 4 blocks--2 blocks on the left, 2 on the right. That's ~32lb of wood. What it's done is produced a very lively and wide secondary combustion zone in the ~2 inches between the top of the blocks and the baffle (particularly the firebrick baffle extension I have sitting on top of the stock baffle) where the blocks are mostly glowing bright red in the middle with no flames, black on the front/sides, but very lively blue & yellow flames dancing around off the top of the blocks and very good heat (650F stovetop, 305F at the single-walled fluepipe-to-thimble connection, 700-800F at the front top dental trim). I have a fan blowing at the stove and it's heating the place wonderfully. Oh almost forgot to mention, the chimney emissions appear to be clear, can't see any smoke...

It does seem that the real trick behind the Jotul 8 1st gen model is to stack wood high up near the baffle, as that provides the heat to drive the secondary combustion zone up top. If the baffle had a refractory insulator underneath it like modern non-catalytic stoves, it'd probably work better with smaller loads like modern stoves typically do. But those 8lb compressed sawdust fuel blocks are a good length to stack vertically and enable lively secondaries. I'd imagine stacking cordwood E/W that high would be difficult due to the arch in the door, however if the splits were bucked short enough that you could pile them vertically in the firebox, that might work... I doubt many folks load their stove that way...

 

[spirilis]

Still loving the vertical fuel block fires. Figured out that with 2 blocks, and ~3/4 air open, a steady inferno of blue/yellow flame engulfing the upper firebox and lazy dark-blue ghost flames midway down the blocks, the stove cruises around 550F or so. After ~20-30min it makes sense to briefly open the door and push one of the blocks closer to the other (otherwise, the center-facing surfaces of the blocks grow dimmer... closer together they're more cherry red). But if I want to push it up to 650F, shifting one of the blocks back away and shoving a 2lb WoodBrickFuel block in between them will let it go nuclear (well, ~650F...)

 

[spirilis]

Finally opened the wallet last night and purchased a DuraLiner 6" system which I'm going to install myself. Excited to get that chimney relined and see how that Jotul 8 shines with a proper flue!

 

[spirilis]

The new 6" DuraLiner seems to work quite well. Hooked up the stovepipe tonight and got a small firestarter fire going... not much, but it did seem like those flames jumped up way high way early after torching them off. It's gonna be a warm house this winter.

 

[BrotherBart]

Bout time.

And I repeat, you are having entirely too much fun.

 

[spirilis]

Still having way too much fun!

Fired up a small shoulder season load this morning, impressed how quickly the firebox was filled with flame (raging inferno at mere 130F stovetop) and how far I had to damper it down to avoid overfire.

 

[Live Free Or Die N.H.]

Pal you are a heaven sent with this blog (whatever you'd call this) about your Jotul 8 stove. I just bought and installed mine last Thursday and what a joy this has made my new home. The house has electric heat and I'm cheap which means my home would never have been heated past 60 degrees. the house did have 2 wood stove flues (unfortunately both going into the same 7" x 13" chimney flue, but maybe in 1984 that was code, but it aint now) and I have tried to follow what you've said you did with yours. It's an 84 and I bought it for $400 and had to replace the glass (which amazingly the dealer happened to have one sitting on the shelf downstairs) and all 3 gaskets. Unfortunately I had to top vent the stove due to safety and spacing issues but I have 5 feet of pipe before it enters the brickwork so I get a lot of heat out of the pipe itself.
I don't use those fuel blocks but but I can usually get a smokeless fire within about 5 minutes or so after starting this furnace up. It's 40 degrees up here tonight and my house is 79 in the living room / kitchen area, and the bedrooms on the other end of the house are all about 73. I've lived in New England all my life and can't remember my house EVER being this warm in October.

Could you possibly post a picture somewhere of the inside of your stove with the brick setup to retain the heat better? Your blog is what got me to say I'd buy this particular stove and now that I've used it and taken it apart I understand a lot more of what your saying in your posts, but I don't see how or what you'd attach firebricks to, to retain heat. If you could do this I'd greatly appreciate it more than I already appreciate all the other things you've posted. Thanks also for the stoves manuel, it was a blessing.

 

[spirilis]

I'll try to get a pic tonight or this weekend. They're thin firebricks, and they're literally sitting on top of the baffle (overhanging the front a bit). If you are top venting it's probably best to place them together at the center so the flue gasses need to move around the bricks before entering the flue. Assuming that doesn't restrict it too far... either way, a well drafting chimney can compensate for such draft restriction.

 

[spirilis]

Playing with a 3-brick fire tonight. That's just 6lb worth of fuel. The vastly improved draft makes this practical. I keep thinking a good mod/tool to have would be a pair of insulative refractory pieces flanking the simple half-pyramid, providing a hot surface to intensify the flames on the open sides but leave enough gap for primary airflow. Might play around with wood ashes + furnace cement at some point, or maybe castable refractory. Shorten the effective firebox size. Removable, of course. Regardless, this tiny fire has the stovetop around 550F although it took its time getting there. Lots of cast iron to warm up.

 

[spirilis]

Playing with a mod I'm hopeful about- Bought a 2ft x 2ft x 1/8" piece of ceramic insulation from a vendor on ebay, pulled down the Jotul's baffle and traced out a piece of insulation that could hang under the baffle; it gets crunched like a gasket at the baffle-back plate connector and gets sandwiched under the side "ears" the baffle rests on.

Sags a little in the middle but not that bad. A very small fire tonight, didn't even hit 500F, but I noticed the top wood brick eventually became a column of flame, and long after the wood underneath stopped flaming that top brick had dancing blue/yellow flames all over its top surface. The top of that wood brick faced the baffle insulation up above, roughly 6" away.

At the coaling stage of the burn, those wood bricks were pretty solid coals, didn't fall apart upon poking around. Could have broken them apart but I would actually had to try.

Curious to see how well this will work with a normal or much larger fire. Bet it'll be noticeably more efficient of a burn.

 

[spirilis]

Well having insulation "hanging" under the baffle was a failure; after 1 or 2 good fires, the insulation becomes softer and just fell apart. Of the remaining that I have, I am going to put it on top of the baffle instead and call it good.

 

[spirilis]

Did my first overnight fire last night ... it was 6 woodbrickfuel and two TSC fuel blocks, so about 30lb worth of wood. Kept the house warm all night, around 74F when we woke up, and while the stovetop was 115F there were still big chunks of coals but all around the perimeter of the firebox... consolidated them with the ash rake & sprinkled some wood pellets on top, opened the air, fired her right up to burn them down (~150F after 5min). Had the air dialled way down to 1/5 open or so all night. Had a few sketchy spots of caramel on the glass, so maybe that was just a tad too low, but overall the glass was clear so maybe not.

That load was put in (as a reload with stove ~250F) around 9PM, so that's 9 hours of heat. It'd probably fall short of avoiding the heat pump once the temps go below 25F unless I stuff some more in there.