In Praise of the Undersized Stove - The Oslo Experience

[jotul8e2]

Our first full season with the new Jotul Oslo is winding down, but not yet over. It is time to review some of my preconceptions and see how or if, they intersect with my experiences.

An enormous amount of research, thought, study, reading, and searching for advice went into the choice of our stove. In the end we went with the one the wife liked: Ivory enamel Jotul Oslo.

Frankly, I had my heart set on the Jotul 600 for our 2500 sq. ft. + house (not counting the 2000 sq. ft. basement). Even here in SW Missouri, where it seldom drops below 0 deg. f., it seemed like a more reasonable size for this large a house, even considering that it is very heavily insulated. But what finally made me see it her way (aside from wanting to continue to live here) was the realization that the extreme temperatures which would necessitate something the size of the Jotul 600 ocur only a few days each year, while the moderate temperatures (where a really large stove would be too much) stretch on for weeks and weeks.

And so it is. Here we are nearly at Easter and we have a nice fire running 350 deg. and keeping the house just warm enough. This seems to be fairly easy to do up to about 55 deg. f. ouside temperatures. Even when daytime temps run up into the 60's I can build one good fire in the evening, or sometimes just every other day, and the house will stay comfortable. It does not seem likely to me that the larger 600 would do this as easily, and maybe not at all: EPA stoves, particularly non-cat models, do not really like "small fires".

"But what about those 0 deg. nights?", you ask. As it turns out, the Oslo keep up quite easily, keeping the main part of the house at 68 deg. or better. It did take a while to "catch up" - about three hours, actually, when we were away all day, but the family room warms up quickly, so we were never uncomfortable.

I'm not going to claim all night burns, or even go to bat for Jotul's claim that it will burn eight hours. However, with practice I find I no longer have to load the stove in the middle of the night. A full load at 10:00 pm will leave a good pile of coals to light off the morning fire if I get around to it before 6:30 am or so.

The other leason was learned early on, and has appeared on these forums many times, but I don't think it can be repeated enough: the Oslo and other EPA non-cat stoves need dry wood. Think arid, dessicated, parched, sere. "This seems dry", isn't.

Mark

 

[johnn]

Nice write!! You appear to be pleased with the stove which tells me the "Wife" is Happy. All`s good!!

 

[Jags]

The other leason was learned early on, and has appeared on these forums many times, but I don't think it can be repeated enough: the Oslo and other EPA non-cat stoves need dry wood. Think arid, dessicated, parched, sere. "This seems dry", isn't.

Mark

Hmmm....never heard of that. %-P

This is the most repeated newbie mistake in the book. Darn kids!

 

[karri0n]

Dry wood? Whoda thunk it???????

Hey if you want to be able to go to 7:30-8:00 from a 10:00 pm feeding, maybe for next year you'd be interested in a pipe damper. I absolutely needed it, as a 10:00 PM fire would usually be down to ash by 3:00-4:00 AM, and that's on a 3.0 CF firebox. Now I can go from 10pm almost to 10am

 

[Todd]

EPA stoves, particularly non-cat models, do not really like "small fires".

"Mark

Glad your stove is working out for you, but I have to disagree with that statement. My experience is small hot fires work just fine in larger stoves if you don't need as much heat in the shoulder seasons.

 

[begreen]

Yes, perhaps it depends on the stove and flue setup. We do a lot of shoulder season burning. Short, hot, half-fires have been standard operation for us with the Castine and the Alderlea.

 

[jotul8e2]

EPA stoves, particularly non-cat models, do not really like "small fires".

"Mark

Glad your stove is working out for you, but I have to disagree with that statement. My experience is small hot fires work just fine in larger stoves if you don't need as much heat in the shoulder seasons.

Short, hot fires I understand. But the concept of a "small fire" that will either activate the combustor (cat stove) or the secondary burn tubes (non cat) is one which I cannot grasp. Either way, a certain number of btus is required, and the larger the firebox the larger the number of btus required. And the larger the number of btus, the warmer the immediate surroundings. A "small fire" is not going to burn efficiently or cleanly. If I need just a little heat, I fire the stove up as usual, let it come up to operating temperature as usual, and just don't feed it. In our setting the Oslo does not overheat the room on those 55-ish sorts of days, so long as I have the good sense to stop while I'm ahead and just let it burn down. If the room was larger, or the floor plan more open, this might work as well with a larger stove.

Of course, the other possibility is that I am missing something important here.

Mark

 

[begreen]

Actually, it takes awhile for the mass of many stoves to heat up. If the firebox is well insulated, there can be good secondary combustion before the stove is radiating (or convecting) strongly. Our Castine would come up to firebox temperature very quickly. I usually had good secondary burning in about 15-20 minutes. But if I let the fire die out afterward, the overall movement in room temperature would only be a few degrees. The T6 takes even longer. I can have a hot firebox but it takes about 45 minutes before the mass of this big stove is really starting to heat up. And it takes even longer, to move the interior mass of the house to more that a few degrees an hour.

However, once all that mass is warmed up, it can be maintained with much less heat. For the T6, an hour or two burn with a few logs when it's 45-50 outside is not a big fire. We will get secondary combustion and the stove top might make it up to 500, but that's loafing for this puppy.

 

[BrotherBart]

Of course, the other possibility is that I am missing something important here.

You didn't miss anything. Large firebox stoves are a pain in the butt to burn small fires in. The reason it is so hard for them to get good EPA numbers. Burn it clean and you have a big hot box radiating heat in the room. Period. Paragraph.

Small hot fires make small hot stoves. Small hot fires make big hot stoves. The little one cools off before you are sweating various body parts off.

 

[Deep Fryer]

I'm not going to claim all night burns, or even go to bat for Jotul's claim that it will burn eight hours. However, with practice I find I no longer have to load the stove in the middle of the night. A full load at 10:00 pm will leave a good pile of coals to light off the morning fire if I get around to it before 6:30 am or so.Mark

This was my first year with this model & with wood stoves in general & was quite happy. Never did achieve the elusive 9hr burn either. Always had coals in the morning but the stove was not putting out anything substantial (heat wise) after 4-5 hrs. That was a bit of a dissapointment. The other thing is I need to figure out how to get the heat into the other rooms, on cold nights you could feel a bit of a nip in them. Overall I am very happy with my first year of burning wood in my stove, I actually think I could have used the larger model in my situation.

Hey if you want to be able to go to 7:30-8:00 from a 10:00 pm feeding, maybe for next year you'd be interested in a pipe damper. I absolutely needed it, as a 10:00 PM fire would usually be down to ash by 3:00-4:00 AM, and that's on a 3.0 CF firebox. Now I can go from 10pm almost to 10am

karri0n
Could you shed a little more light on this Pipe Damper scenario, your ideas intrigue me & I would like to subscribe to them.
The ash by 3am is right on the money & I would do my last feeding at 10:30 or 11:00pm

Great fun nonetheless!

 

[karri0n]

Sure deep fryer. I have a big 30 foot 8 inch chimney coming off my 6 inch flue outlet, inside a centrally located masonry chimney. This made a monster of a draft, great for starting a cold stove and getting plenty of heat out of the stove, but the high draft was also stealing a lot of my heat and shortening my burn times. I installed a 9 dollar key style pipe damper in the pipe to slow the draft. Now I open the damper, load the stove full, throw some kindling or a firestarter in the front, light it. Wait 20-30 minutes for the load to be going strong, and start closing the air down. Once I get the air closed down all the way, I close up the pipe damper and make sure secondary combustion doesn't stall. As long as I'm sure the secondary is still going, experience with this setup tells me I will have a nice, hot coalbed when I get up at 7, 8, sometimes even 9 am the next morning.


edit: one of these guys, available at Home Depot, Lowes, Harbor Freight, Tractor Supply, most hardware stores, or your stove dealer $10, completely priceless in my eyes when it comes to how much my performance was increased. I'll never look back.

 

[Deep Fryer]

Hi KarriOn!
Thank you for the information, that seems to make a lot of sense to me, I just did not know that one could put a damper in the pipe as well in these kind of set-ps. I suspected that a good amount of heat was getting sucked up the flue as well.

Now with this kind of set up, do you still damp down the unit/stove itself to maximise the burn time or is that something one should really experiment with.
I would imagine that the damper gets installed just above the elbow area so that one may have access to it?
Any particular instructions/advise in regards to intalling the damper?

One last question, is there a chance that the damper might close up by itself, meaning, the opening & closing mechanism is snug enough that it has to be manually operated?

Thanks again, I am grateful to you sir!

 

[karri0n]

Manufacturers do NOT recommend pipe dampers for EPA stoves as they slow the exhaust flow and can possibly lead to creosote condensation, however the stoves are "tuned" if you will, for a 15 foot straight vertical run with not so extreme differences between indoor and outdoor temps. Vary too far out of this and you can end up with a vacuum pump for a chimney. Over-draft will burn your wood up FAST, and rob precious heat. Too far in the other direction, and you end up with nothing more than a big tube for the smoke to lazily meander through, spreading creosote as it cools.

You absolutely still need to use your air controls. The air controls are the way of controlling the stove, period. The damper is only there to remedy an over drafting issue, and to give you a bit more fine control once you have the air dialed in the way you want it. I made this mistake once. I decided to try leaving the primary just a touch open because I didn't want to wait longer before going to bed to turn the air down, and I didn't want it to stall and smolder. I left the primary very slightly open and closed up the pipe damper all the way. My normal operation would be both all the way closed, but like I said, it was stalling when I did this and I wanted to go to bed. I even got up early the next morning because I figured the coals would be a bit lower than usual. Where I normally would have expected a healthy pile of coals, I opened the doors and found nothing but fine white ash. It seemed like it burned just as fast if not faster than before I ever put the damper in.

It may be prudent to mention that many people recommend not closing the damper all the way, and some even go so far as never closing it further than 45 degrees. In my setup, leaving it open 45 degrees certainly did slow the draft, but I still got much shorter burns than my stove manufacturer and others who have the same stove report getting. I didn't find it at all detrimental to close the damper all the way. Once again, however, each setup is different, and I attribute this to the fact that I have 30' of 8 inch pipe attached to my stove made for 15-20' of 6 inch pipe, in a centrally located chimney with really cold outdoor temps. If your chimney is shorter, or your temp differences less extreme, or 6 inch and not 8 inch, your results will vary. A bit of experimentation usually will get you your answers pretty quickly.

I have 2 90 degree elbows directly off my stove which then go right into the blockoff plate, so my only option was to install the damper at the very bottom of the first elbow, only slightly above the flue collar. Depending on your pipe setup, you can install it as high or low as you like in regards to your comfort, ease of reaching, and ease of install.(i.e., in my setup, my arm is less than an inch from the stovetop when adjusting the pipe damper... a bit warm).

I'm not sure if you have single wall or double wall stove pipe, but if it's double wall, you will need to get one of the sections with the damper already installed into it.(I believe the Selkirk banner you can find down below carries this)

In regards to advice about installing, it took me a bit to figure out how to get the pin out of the thing, though it was much simpler than I made it. You need to push the pin inward in respect to the outside of the damper with a bit of force, as the spring is relatively strong, and the curved part might be stuck. once you push the pin inward, it releases from the nook in the damper plate and you can slide it out easily.

Good question regarding the self closing damper. The thing was plenty tight the first couple days I had it, but this was not the case after just one week. My damper did indeed fall on its own and close, sometimes when loading the stove which gave me a faceful of smoke. I remedied this issue by putting a lock washer with teeth on the end between the spring and the pipe. That tightened it right up and I haven't had an issue since.


EDIT: It should be said that if you are getting short burn times, it's definitely best to make sure you do not have air leaks before running out and getting a pipe damper. How old is your stove, and when was the last time you changed out the gaskets? What is your chimney setup and length?

 

[Deep Fryer]

Thank you KarriOn for your insight into this particular area, no doubt this will be very beneficial to me & others with similar experiences & expectations of our stoves. Will keep it in mind this summer as I replace the flexible liner with a double walled one. If I can get a more efficient burn out of the stove that can only be a good thing.
It just seemed to me that unless I damped down hard the wood was just burning too fast, so maybe this will remedy that situation.
Will also be inspecting the stove very closely this summer to make sure there are no air leaks that might be aggravating the issue as well.

EDIT: It should be said that if you are getting short burn times, it's definitely best to make sure you do not have air leaks before running out and getting a pipe damper. How old is your stove, and when was the last time you changed out the gaskets? What is your chimney setup and length?

My stove is brand new, this was the first season in use, & I have maybe a 20' chimney run of 6" pipe. My concern with air leaks stem from when I was breaking the unit in, uring my second burn it got away from me and shot up to almost 600. Now I dont know what impact this had if any but that would be my only suspect as to the fast burns. Can you or some of the other members shed some light as to how one might go about checking for air leaks in a unit?

jotul8e2, I hope you do not consider this a hijacking on my part as I believe this information is relevant to your post & will benefit all who might have similar concerns. If you dissagree pm me & I will post in separate thread.
BTW: I kinda wish I'd gotten one of the enameled models as my black unit seems to insist on discoloring/haze at the very top center of the stove.

 

[Jags]

It just seemed to me that unless I damped down hard the wood was just burning too fast, so maybe this will remedy that situation.

Please keep in mind that if you have the ability to clamp down your stove to a very low burn point or maybe even to the point of not getting full combustion (some unburnt coals left when stove is out), that a pipe damper may do you no good.

A pipe damper will probably not increase burn time if you already have "full" control of the stove. They should only be used with an EPA stove if you have a need to have "additional" air control beyond what the stove supplies.

 

[Deep Fryer]

Point duly noted Jags!
I need to do a bit of investigative work before I make assumptions as to where (if any) the chink in my set up lies. KarriOn's set up is different from mine in many regards but I will keep it in mind as I progress along this road.

Thank you much!

 

[Jags]

Point duly noted Jags!
I need to do a bit of investigative work before I make assumptions as to where (if any) the chink in my set up lies. KarriOn's set up is different from mine in many regards but I will keep it in mind as I progress along this road.

Thank you much!

Good on ya!

KarriOn - has a setup that creates excessive draft. His was a prime candidate for a damper. If you don't have a NEED, you may actually cause problems by using a damper.

 

[Deep Fryer]

Agreed! My goal in most endeavors these days is to simplify things rather than coplicate (& I have a good history of the latter )

 

[ansehnlich1]

jotul8e2,

I too have the oslo and think I could use the F600 at times. Here in Pennsylvania we had some below 0 nights. But I'm in the same boat as you, I think the bigger stove would roast me out at times and be harder to control my home's temp's when it's 45 to 55 degrees.

I get good small burns and good secondary action with 3 splits of dry sycamore laid east/west on top of about 5 small pieces of split 2x4's laid north/south.

The oslo is a good stove. I always have a good bed of coals in the morning to fire it up again.

 

[snowtime]

Making generalities about stoves whether they are non cat or cat doesn't fly. Maybe small hot fires have not worked in some EPA stoves I am thinking maybe downdraft but I could be wrong as I do not have one BUT our T6 loves a small hot fire. We burn day after day during the shoulder season with it just getting 2 or 3 rounds for one hot fire. Today it is 28F and it heated the house up to the 70F and will stay there until the next day. Assumption can be a killer of knowledge.

 

[karri0n]

Making generalities about stoves whether they are non cat or cat doesn't fly. Maybe small hot fires have not worked in some EPA stoves I am thinking maybe downdraft but I could be wrong as I do not have one BUT our T6 loves a small hot fire. We burn day after day during the shoulder season with it just getting 2 or 3 rounds for one hot fire. Today it is 28F and it heated the house up to the 70F and will stay there until the next day. Assumption can be a killer of knowledge.

+1

My stove is very big, and I've burned small fires for shoulder season and got clean burns just fine.


edit: Jags, thanks for clarifying that. I should have elaborated more when I mentioned the air leaks thing.

@DFryer;

Getting your oslo up to 600 on its first burn more than likely didn't do anything detrimental. Lots of folks run them that high on a pretty frequent basis.

 

[begreen]

Making generalities about stoves whether they are non cat or cat doesn't fly. Maybe small hot fires have not worked in some EPA stoves I am thinking maybe downdraft but I could be wrong as I do not have one BUT our T6 loves a small hot fire. We burn day after day during the shoulder season with it just getting 2 or 3 rounds for one hot fire. Today it is 28F and it heated the house up to the 70F and will stay there until the next day. Assumption can be a killer of knowledge.

Glad your stove matches mine. A big difference for us is that our stove is a whole house heater - without a fan. We heat strictly by convection (and the ecofan). It takes time for a fire to a) heat up the stove exterior jacket plates and b) to warm up the house.

 

[BrotherBart]

Nothing general or assuming about the fact that a big hot stove tosses more heat than a small hot stove, longer. Own'em both. Too often here the "burn a small hot fire in a big stove" is tossed out without saying "and let it burn down and/or go out". Giving new stove users the impression that just because you are burning two or three small splits clean the stove ain't gonna be getting just as hot, and the area around it, as it would be if it was packed to the gills and damped down. Get that firebox up to clean burning 1100 degrees and something is going to get hot around there. Steel, cast, soapstone, steel prettied up with cast or whatever. And stay hot if you keep feeding it.

Ya ain't gonna burn a clean, constant, low heat output burn in a large firebox stove. It ain't gonna happen.

Let the flames begin.

 

[Todd]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

 

[BrotherBart]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

No you won't. While the firebox in the big boy is getting up to secondary burn temps the little boy has been there for a while already. With the big boy those BTUs are going up the stack.