New Oslo questions

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MarkC

New Member
Dec 31, 2011
20
Orange Co., NY
I found this forum through almighty Google...I have poured through hundreds of posts, old and new, and have a pretty good idea what I am going to get in response to my questions.
Everyone on this site, especially the faithful Jotul/Oslo's have impressed me and piqued my interest, so here goes.

I have been heating my 2200+ SF Timber-frame home using 100% wood for 23 years. I just retired a "used-when-I-got-it" 1980's C. Dutchwest CAT.
I typically burned 3-4 cords and the house is always very comfortable. I also use passive solar as a heat source (the coldest days are generally clear). This year I splurged and brought home an Oslo, I felt it was time to get something more modern and safe. The break-in fires were adventurous with smoke alarms, acrid smoke and open windows. Winter has been slow to come, you guys call it shoulder weather (not sure why) and I have been tinkering with the stove non-stop since mid-October. All in all the stove is gorgeous and well made.

Here is the rub:
I don't feel like I have any control of this thing, like a hot rod with a governor. I can't see a difference in air flow between open and closed on the draft control (this is the cheesiest part of the stove by far) and the thing is working right! I took it apart to be sure. I know you are going to say that it takes time to get used to a different system and I agree, 100%. I also know that there have been many posts describing similar and direct opposite problems, with raging dragons spewing 600 degrees and climbing... I don't want that at all. I even saw a series of posts where a guy sold his Jotul and bought another stove because of a problem like I am experiencing. Have they built in too much safety? I think you should see a difference when the doghouse is open vs. shut.

The expected answers are going to be chimney configuration, wet wood and poor draft. Maybe the wood is not 10%, I don't have a Kiln. However 15-17% readings on newly split surfaces of Ash, seasoned 2+ years and used as comparisons, not actual moisture's, make me comfortable the fuel is good. The Chimney is a 3 flu masonry job that is dead center in the middle of the Salt Box house. I clean it myself and it is both well designed and in excellent shape. It draws like no tomorrow. I have outside air piped directly to the stove, through the slab, because the house is very "tight". I do not have the Jotul kit...

What I am really asking you all, as the real Jotul tech advisers: is there anything I am possibly missing mechanically with the stove that you have seen, experienced or heard of? Or, am I just stuck in my ways and need to be more patient? Change is tough for us old-timers...

I appreciate any/all input. It is finally supposed to get colder (8-10 F) tomorrow night so I can maybe strech this baby out.

Thanks a lot,
Mark
 
your pretty much correct sir. Its either off or on, there might be a little on the just open side. the load seems to prettu much regulate it
 
Hello, Markl! Welcome to the best message board on the 'net! :)

Sounds like you do know wood burning but you did leave out a little info:

1. Tell us a little more about your chimney. Three flues - is your Jotul chimney lined? Do you have a 6" stainless liner? Do you have any 90 degree or 45 degree connections in your chimney anywhere? How tall is your chimney?

2. Tell us about the weather (temps) you have been having. My Oslo runs a bit sluggish in warmer weather but runs like a champ with anything mid 50's and below.
 
That was quick!
I am not exactly sure of the actual chimney height, 2 stories plus 3' above the peak of the roof.
I have roughly 3' of DW up/out of the stove vertical, a 90 and then 28-30" of dw into a new stainless 6" thimble. It is rectanglular terracotta flue from there on up to the top, no liner. An interior chimney is warm, CMU block and stone facing is great thermal mass for solar and wood. I can't justify a $2000+ liner with a great chimney like that.

Weather has been between lows of 20 at night (ave, 30's) and up to 40-50's during the day, basically since we got the stove. Today it was 33-52F and sunny. Still 50+ as I type this. No fire needed in this weather, it's nearly 70 in here with no fire since the ball dropped last night.

Thanks for answering so quickly,
Mark
 
There is a difference in the air control settings for sure. Do this, wait til it's below 30 outside, pack that oslo with your good, dry ash, and leave the air control wide open.....report back here what stove top temps you achieve AND the length of time until that load is burned down (sarcasm intended, if you do this you will likely overfire your stove....if you do this and you do not overfire your stove, then you surely have a wood, chimney, or other issue)

Next, in similar weather, pack it again with that same ash, open that air control wide open and run that stove top up to 500, then set that air control to half way for about 2 minutes, then close it near, or completely off, and report back here what stove top temps the oslo maintains and how long that load of wood lasts.

Today it was warm here, but I still had a fire. I'd throw 3 small splits of cherry on there at a time and let the air control at half open. That gave me a decent burn and didn't blast us out of here. Some of the technique is in the wood, the type, the amount, the size of the pieces, etc. It ain't all about the air.

Honestly, it sounds to me as though you are in the midst of a learning curve and all is well. The oslo is a serious heater, as I've posted here recently. My wife and I built this home 5 years ago (2200 sq ft), we installed the oslo, and we have oil hot air heat. We've literally burned 80 gallons of fuel oil in 4+ years.

We burn approx. 5 cord of oak, walnut, cherry, locust, hickory, ash and maple each winter and it's truly a hoot to never see an oil bill.
 
I'd be interested to know the dimensions of that interior chimney too. You know, new stoves vary greatly in temperment, and the oslo surely operates best with a 6 inch flue all the way up and out. If you have an 8x8 flue or some such large size it will have an immense effect on the performance of the oslo.
 
Mark,

Welcome to the forum and your change to an Oslo. I made the same change from a CDW cat stove. It looks like you have done your research.

There is a significant transition between these stoves. You touch on few issues in your initial post. Making sure your set up is correct should be first, and then comes operating issues.

It sounds like the chimney height of 2 stories + chimney above the roof is more than enough height. However, you said that you are using the center flue of a 3 flue chimney w/o a liner. This may be fine if the flue cross-sectional area of the center flue is not too much larger than the area of a round 6" diameter. What are the cross sectional dimensions of the center terracotta flue?

Is the problem that you are having just during start up? E.g., getting the draft going. Or are you having problems after an hour with getting the secondaries firing and getting your temps up? If your you can give us more details about what is happening, we can provide you our perspective.

Sean
 
MRC said:
That was quick!
I am not exactly sure of the actual chimney height, 2 stories plus 3' above the peak of the roof.
I have roughly 3' of DW up/out of the stove vertical, a 90 and then 28-30" of dw into a new stainless 6" thimble. It is rectanglular terracotta flue from there on up to the top, no liner. An interior chimney is warm, CMU block and stone facing is great thermal mass for solar and wood. I can't justify a $2000+ liner with a great chimney like that.

Weather has been between lows of 20 at night (ave, 30's) and up to 40-50's during the day, basically since we got the stove. Today it was 33-52F and sunny. Still 50+ as I type this. No fire needed in this weather, it's nearly 70 in here with no fire since the ball dropped last night.

Thanks for answering so quickly,
Mark

Mark,

Hmmmm.... so your chimney is not lined = this is called a 'slammer' install. Some people here on hearth.com have no problem with a slammer install while others have converted to the manufacturer suggested 6" liner and find a great difference in how their stove runs and heats.

What is the size of your rectangular terracotta flue? And you state your chimney is 'warm'. Sounds like you are heating your chimney instead of your home. A liner would help keep the heat where you want it instead of letting all that heat go up the chimney. Yes, liner costs are hard to swallow but if it makes your stove run correctly......
 
"Sounds like you are heating your chimney instead of your home"

They are one and the same.

My 3 flu, fieldstone/masonry chimney reaches 2 stories and is the focal point of my home. It also does heat the house
By having the chimney centrallly located it allows the hot chimney gasses to continue unempeeded and particulate is expelled from a warm chimney more efficently. Thermal mass does not flucuate like air. That massive stone and masonry chimney will store more heat, both solar and wood generated, than you can imagine. As far as the "slammer" description, I don't quite understand that reference.
Not exactly sure of tile lining demension, it is rectangular, maybe 4x8"?

To further describe what is happening; I first go back to the Jotul manual which says clearly not to use the ash door to manipulate draft ( I paraphrase... ). Guess what I did when I couldn't get a decent response from the controls provided? Bingo, the damn thing does work! I still use the ash door to speed-up the coals-to-fire transition in the morning. I work and cannot hang aroung for an hour waiting for the meager air alloted by these controls to get a decent burn going...It does seem to burn pretty well after I get it going, i do not believe however I have passed a 400 or possibly 450F surface temp though. I have a spanking new Jotul surface thermometer on the left corner as shown in the manual and I watch it religoiusly (never had one on my old guy so I can't compare them).

Bottom line is it sounds like it is just me and my desire to have more control. I like to be able to make it roar and to pull fire from coals.

I have also decided I am not a fan of the ash pan... how do you bank coals over a grate?

Mark
 
I had the same issue with my Oslo. It was installed in a terra cotta lined chimney with a large flue tile as it was originally designed for fireplace usage. Like yours, it drew as if there was no tomorrow (we live on the coast and the relatively constant wing seems to accentuate the draft). I had good wood and 40+ years of woodburning experience with over a dozen different stoves, including 6 EPA stoves, and while I'm still learning things, I felt pretty confident in my burning techniques/approach.

I first added a 6" liner, as recommended and while it helped just a bit, it didn't effectively deal with the issue: expensive stove and no heat. The draft was no doubt cut back by the liner, but it was still quite strong and I figured that most of my heat was literally being sucked up the chimney. Next step was to add a $5 in-line damper. This resulted in a substantial improvement in the stove's heat-output performance. I would typically have to damp the stove by at least 3/4 (closed) to get good performance.

However, I was still unhappy with the burn profile of the stove - like a negatively skewed sine wave - and much preferred the more level heat output profile of the catalytic Firelight at the other end of the house. At this point I had the better part of 2 years experience with the stove and felt that I had pretty much climbed the learning curve. It is quite possible that the damper, while solving one problem, created another. I checked with other owners and a number had experienced the same "burn profile" problem, while others felt it was normal behavior and a several said they didn't have this issue and could get a good, "reasonably level" burn considering the fact that it is not a catalytic stove.

In the end, I sold the stove and got another catalytic Firelight. I installed it in the same location, same liner, wood characteristics, etc. and it runs just fine (just like the one at the other end of the house). Hopefully some of my experience may prove useful to you. YMMV

Also, you may want to completely eliminate wood seasoning as a factor by buying a bundle of kiln dried wood or a few bio-bricks and see if your surface temp. increases.
 
Actually the side loading option is one of the things that made me buy the Oslo.
I saw several stoves with front, top loading options and did not want anything to do with those.
Don't understand that having anything to do with the doghouse opening though.
 
I forgot to mention that I also bought and installed a significantly more expensive damper section($50+) of double wall pipe as I felt comfortable with that little extra cotrol it offered.
So far that investment has not made much difference. I really don't see myself selling this stove but stranger things have happened...
 
MRC said:
"Sounds like you are heating your chimney instead of your home"

They are one and the same.

My 3 flu, fieldstone/masonry chimney reaches 2 stories and is the focal point of my home. It also does heat the house
By having the chimney centrallly located it allows the hot chimney gasses to continue unempeeded and particulate is expelled from a warm chimney more efficently. Thermal mass does not flucuate like air. That massive stone and masonry chimney will store more heat, both solar and wood generated, than you can imagine.

I can imagine as we also have a centrally located, stone on 3 sides, former fireplace. :)

Regarding your statement "hot chimney gasses: The newer EPA stoves, like your stove, are designed to have cooler flue gases. This is the nature of the modern beast. :)


MRC said:
As far as the "slammer" description, I don't quite understand that reference.

"Slammer" means the stove does not have a liner reaching to the top of the chimney cap.

MRC said:
Not exactly sure of tile lining demension, it is rectangular, maybe 4x8"?

More than likely it is somewhere around 8x11 or 7x10 - way too much draft from your stove.

MRC said:
I work and cannot hang aroung for an hour waiting for the meager air alloted by these controls to get a decent burn going...It does seem to burn pretty well after I get it going, i do not believe however I have passed a 400 or possibly 450F surface temp though. I have a spanking new Jotul surface thermometer on the left corner as shown in the manual and I watch it religoiusly (never had one on my old guy so I can't compare them).

When the stove is burning, try moving that thermo to a different corner during a decent burn. Also, I would suggest getting an IR thermometer to verify your thermo is reading correctly.


MRC said:
I have also decided I am not a fan of the ash pan... how do you bank coals over a grate?

Easy - you don't. Sounds like you are emptying your ash pan too frequently. Let the ash build up until you have about 2" inside the stove. When your ashes reach around 3", empty the ash pan. Rake down a few ashes but don't empty the interior of the stove completely.
 
Mark,
I'm in my first season with the Oslo as well. I'm running it to an 8" insulated liner and experience some sluggishness when it is warmer out. I am taking my time, being patient, trying different things (wood size, species, loading north/south, air controls, etc).

Take your time. Experiment on the weekends or when you have time to sit and monitor it. You will love it when you get it figured out. I got a 9 1/2 hr burn the other night and I'm still learning.

One more thing, don't use the ash pan door, they will fry you here for doing that! :shut: it works, but it can heat the stove up too fast and ruin the grate/bottom. It can also lead to bad habits. The last thing you want to do is forget you left that thing open and walk away for a while. :bug:

Good luck
 
The primary air control works, it is just a bit non linear. Watch the burn closely, as you open and close it. It works very well and has the most control from 50% to full left which is fixed to about say 30%.

The secondaries, above in the 3 tubes, are always open.

Wood species and level of seasoning greatly affect the burn. Your experience goes a long way.
Be patient, stay warm and always burn safely.
 
We bought an Oslo in October and are new to wood burning. It took a good two weeks to get the hang of the stove. I have found the air control to be pretty responsive. Maybe it's cause I have no experience with other stoves. On a full load of alligator juniper that was started off a bed of coals, I usually get it going good then after 10 mins I close to halfway and wait another 10 mins then shut the control down leaving it a hair open. The secondaries fire up and we get a couple hours of that. We are getting 8 hours of useable heat and unless it's a really cold night we usually are good with a load of wood at 9pm till 5am. Hope you get it figured out.
 
Mark,

One issue that I had to learn in my switch from a big cat stove to the Oslo was to use smaller size splits then what I used in my CDW. For hot fires in the Oslo, it likes several 3-4" splits rather than fewer big splits like I used to put in my CDW. The smaller the split size, the faster the fire gets going hot and the hotter the stove top gets. However, the fire will burn quicker. Also, if you have dry wood, under 20% mc, and you have adequate draft, and use small enough splits, you will not be able to keep the temps from going to 550 or 600 unless you shut down your primary air. When you want longer burn time, then you'll learn to balance using big splits in the bottom back with smaller splits on top. Also, it is easier to use a big split or two when reloading if the stove is already hot and you have a healthy bunch of coals.

A couple other issues, don't get into the habit of using the ash tray door. The side door will provide the necessary extra startup air once you get a few flames on a restart. Also, there is a big difference between a 4 x 8" (32 in2) flue and a 6 x 10" (60 in2). The first should be fine, the second may cause problems. [EDIT: The second WILL be too big - as it is more than twice the area of the recommended 6" round flue]
 
Master of Fire:
I get that the control is more accurate on the left than the right 1/2, but why can't I see a more dramatic difference when shutting it down or openining it up?
Way too slugish in my opinion. Plus the little bent rod is just cheesy. Lastly, why should you need a welding glove to adjust it? It gets really hot down there... Everything else is soo Ergonomic!

Shari,
Thanks for the clarifications, now I see what you meant with the slammer reference.
I do not however see how you leave ashes above the grate without making a tremendous mess.
I have been emptying it every couple of days and it still spills out sometimes.
Plus wouldn't that interfere with the 3 little holes that feed the fire?

Mark
 
MRC said:
I forgot to mention that I also bought and installed a significantly more expensive damper section($50+) of double wall pipe as I felt comfortable with that little extra cotrol it offered.
So far that investment has not made much difference. I really don't see myself selling this stove but stranger things have happened...


I wasn't suggesting you sell it - just telling you my story. The takeaways: 1. Eliminate wet wood as a possible contributory factor, 2. Try an inline damper - for $5 you have nothing to lose and many people have used them with great results and finally, 3. Try a full-length 6" liner, your flue is oversized for the application.
 
Also, a terracotta interior chimney is at 60-70 F when you start your fire. It takes more time to warm up all that mass in the masonry chimney than if you had a chimney liner containing the heat. Draft is directly proportional to the difference in temp in your flue/chimney and the outside temp.

The interior terracotta flue may work, but could affect the draft more than you think, especially as the heat is warming the terracotta and when the outside temps are not so cold.
 
MRC said:
I do not however see how you leave ashes above the grate without making a tremendous mess.
I have been emptying it every couple of days and it still spills out sometimes.
Plus wouldn't that interfere with the 3 little holes that feed the fire?

Mark

Fist off, I use the side door (always) as I feel the front door spills too much ash. Ashes insulate the coals. When I want to do a morning start-up, I just open the side door, rake down a bit to expose the hot coals & toss in a new, full load and open the air all the way. Leave the side door open for around 10 minutes then close it and I'm off to the races. :)

PS Don't get distracted when leaving that door open for those 10 minutes. I do the above & then head to the kitchen to prepare a cup of cappuccino and then return to the stove room to watch the morning news and keep an eye on the stove temp. :)
 
Green Energy,

I do use 3-6 inch splits for most of my fires. It is extra work splitting and feeding but I again feel like I have more control. I try to always place the larger pieces on the outside(s). I have a whole lot of smaller pieces set aside to get things going and then I feed the fire as need be, smalls to get hotter and a few bigs to last. I also stockpile 3-6" un-splits for hotter fires after the burn is going. Lots of work saved by not splitting the limbs...

Thanks.
Mark
 
Now I am completly distracted as I noticed Wallace's Elk in the Avatar... I have an ornery elk envy going on. Bow or rifle Wallace?

As far as the heat delay on the masonry, most years I don't stop and start my stove. Once it is lit I just feed the beast. This year is wierd for sure. Once the mass is heated I don't see how it can do anything but increase the flow of warm air inside the house up toward the cold outside temperatures.

Does anyone have any experience with the kits for outside air? I wonder if that would have any positive effect?

mark
 
MRC said:
Does anyone have any experience with the kits for outside air? I wonder if that would have any positive effect?

mark

Mark,

While it sounds like you'd rather install an OAK (outside air kit) instead of looking into installing a liner, take a read here to see what a difference the proper sized liner makes: https://www.hearth.com/econtent/index.php/forums/viewthread/72593/

That link is only one of many, many posts by persons who saw the light and installed a properly sized liner.
 
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