I'm not burning the Oslo hot enough

[newatthis]

I was up on the roof, cleaning the gutter, and saw this in the gutter. I knew immediately what it was, and indeed, there's much more on the underside of the chimney cap. This fragment was part of a 3" x 6" sheet (I tried to light it on fire to see how flammable it was.)



I've been slowly learning about how to operate our two stoves, but it's been hard to break from the habits I formed while burning in open fireplaces. I really do think I am learning my lessons, which are to pack the stove much more than I had been, pay better attention to the air, pay better attention to the room and stove temps and NOT the flame, and then either let it cool down, or pack it again, instead of being throwing a split or two on at a time, poking along.

My questions: should we get it cleaned now, or just finish the season and then get it cleaned? Can I reverse some of this with really hot burns? How bad is this shiny black sheeting, compared, say, to the powdery soot I see coming out of the Morso chimney? Is it possible to "preview" how much creosote is in the flue by using a fiberoptic camera? I have been tempted to buy one on eBay. Thanks in advance, my experienced friends.

 

[pen]

With evidence like that, I would definitely want it cleaned now to make certain there aren't other surprises.

Also, if you are closing things down on a full load, and this is happening, I'm concerned that your fuel may not be dry enough, as with a modern stove and good fuel, it should still get up to temp and prevent this sort of buildup.

At this point, I'd almost rather or recommend you putting smaller loads in and leaving the air open a tad bit more, yet still letting things run in cycles, not reloading until you need the temp increase, or are about to lose the coals are OK with the house being a little warmer than you want just to keep the fire going rather than restart.

Are you closing things down so far because leaving the air open a tad will mean things get too warm in the house?

pen

 

[jatoxico]

Pen of course makes good points. An "airier" fire with smaller splits may be in order. You should inspect and possibly sweep since burning some hot fires will not get rid of that stuff up near the cap, it just won't get hot enough and that's not really how to approach the situation any way. You want to burn hot enough all the time to prevent creosote not burn hot now and then in an attempt to burn it off.

Inspect and determine if your whole system is gacked up or just near the cap. FYI Once the cap gets starts getting clogged draft slows which further clogs the cap which slows draft which... any way things can go down hill quick.

 

[newatthis]

We have a moisture meter and had great wood up til about 2 weeks ago. That is why I spent so much on the wood this year (had a previous post on that). Readings had been ~15%. Just now have started a new batch of wood, that has been as high as 20%, but that has been just been in the last couple of weeks.

When I have been distracted and inattentive to managing the air flow properly, I usually have typically been running it with the air open too much. Although sometimes I close it too soon, and it chokes out.

I guess I'm surprised at advice running it with more air, since it will be cooler; but there will be more airflow, I gather.

It is very hard to inspect myself- top of chimney is high. I think I gotta get a sweep out here.

 

[pen]

It is very hard to inspect myself- top of chimney is high. I think I gotta get a sweep out here.

For peace of mind at the extreme least, I agree.

How often do you clean the glass? What is it's appearance between cleanings? Grey / Whitish soot on it that wipes off easily with a damp rag? Black buildup that takes scrubbing?

 

[jatoxico]

When I have been distracted and inattentive to managing the air flow properly, I usually have typically been running it with the air open too much. Although sometimes I close it too soon, and it chokes out.

I guess I'm surprised at advice running it with more air, since it will be cooler; but there will be more airflow, I gather.

It is very hard to inspect myself- top of chimney is high. I think I gotta get a sweep out here.

I think there's a point where adding a lot more air will cool the stove top but that heat goes somewhere so not necessarily the flue temp. Remember with more air the fire is less likely to smolder and the added air increases the volume of hot gases going up the flue. Since the flue size is fixed the flow must be quicker so not only are the gases hotter, there is less residence time.

Sounds like you have a lot of exposed pipe. How long is the chimney?

 

[begreen]

Do you have a thermometer for the stove top or the flue pipe? It helps to know when one is burning too cool.

 

[newatthis]

I haven't bothered to clean the glass yet. Here's what it looks like now:



I just now cleaned most of it, it cleaned easily with a wet paper towel, EXCEPT that glaze on the right, which will take some scrubbing. There are flakes of black creosote on the inside of the stove too.

 

[jatoxico]

According to what you posted, your wood moisture readings are pretty OK. It may be just a matter of sending some more heat up the chimney. Thermometers are mandatory IMO. And I try to read the flame so to speak. So no dark orange black tipped flames, bright yellow and lively, as often as possible.

 

[newatthis]

We finally got an IR thermometer, and I guess I try to keep it at 400, but it drifts down. The magnetic one way underestimated the temp, and I thought it might not have been running hot enough; it's better than I had feared, now that we have have good measurements, but I guess I should be shooting for higher? The flue temp has been lower, but I hadn't been paying it as much attention- thinking it was somewhere in the 200s?, just above the stove?

The flue is not exposed, it's in a large masonry chimney, but I am short, and the flue is on the high side of the chimney (relative to the roof). I think the total height was 20 or 25 feet. Getting it to draft when the stove is cold has been a challenge, but I thought the height was good for that. But I guess if it is a little on the long side, the gases will condense?

 

[jatoxico]

There must be some Oslo threads that describe where to get temps on your stove but 400 peak sounds low to me. Is that because you can't get it higher or is that by choice?

If the liner/chimney is going into a masonry chimney do you have a block off plate and insulation? Without insulating the old damper area and smoke shelf the liner ends up losing a lot of heat and with a long run by the time the gases exit they can be too cool. You have evidence that you're getting just that.

Even if you are capturing heat from the flue and putting it into the room it's not how you want to heat IMO (I have a similar setup with Jotul insert). Keep the flue insulated and as hot as possible, let the stove heat the room.

 

[newatthis]

I have only recently packed the stove enough so that it gets to about 400, but I guess I thought if I was in the middle zone (lower end of it) I was ok. I am definitely not aggressive about loading the stove.

I know we would benefit from a blockoff plate, I was going to make that a summer project. In the other threads on blockoff plates, I've seen some debate about whether or not to insulate it, can't remember what the issue was. It is a cold exterior chimney on the north side of the house, so perhaps we would benefit from that even more than the average hearth.

What temp should I be shooting for on the flue, and is there a standard location for measuring that temp?

 

[begreen]

How is the stove connected and is there a stainless liner in the chimney?

 

[newatthis]

It's a T-connection (the stove is in front of the fireplace) and there is an insulated 6" liner in the chimney.

 

[begreen]

Ah good. That should draw well enough if the liner is at least 16ft tall. I would try running the stove top at 500 and see how it goes.

 

[pen]

Ah good. That should draw well enough if the liner is at least 16ft tall. I would try running the stove top at 500 and see how it goes.

I agree,,,,, but just to be clear, I think a sweep still needs to check things out!

It's been found in the past where creosote build-up was due to things such as a cap not being placed on the bottom of a T, faulty connections between the T or liner and the stove, etc... Since it sounds like you doing this work yourself is out, then I feel a sweep needs to be brought in to simply double check that the install is safe, and to honestly make certain that the accumulations you are finding are due to your burning practices and not the installation.

If it's an issue of burning habits/practices, those can be changed. But if there is a problem with the setup, you are in trouble from the get-go. Gotta make sure what you are working with is sound.

Keep us posted.

pen

 

[begreen]

Yep, get that mess cleaned up and make sure that there are no leaks.

 

[Shari]

What temp should I be shooting for on the flue, and is there a standard location for measuring that temp?

Your manual states your stove should be run between 400-600 degrees with temps being measured from top of stove. I use the right side, rear.

I bring temps up to 450, then lower air to 1/2. Wait till temp gets up to 500 then low air to 1/4. From that point on I don't touch the air - stove temps can raise anywhere from 525 up to 600 after my second air adjustment.

 

[firefighterjake]

I would sweep the chimney at this point . . . but that's just me . . . being all fire safety-like.

 

[Byrond]

Get an inspection. However, your sweep may find very limited buildup in the chimney. Last year I noticed a lot of buildup on my screen and cap and thought the liner would be coated. Well called the sweep and he came out and "swept" the chimney. Barely yielded a cupful from a 27ft chimney. Solution was to take a grinder and modify the screen. The cAp still collects some buildup

 

[newatthis]

Well, I can see a little into the liner, and have taken pictures, which I'll post later, but it looks not so bad. Mainly bits of the shiny black stuff, but not the huge flakes on the underside of the cap. Quick question- I was going to run out now and buy a brush, do I want a steel bristle or a fiber bristle, and do I want the extension set? Maybe this isn't as hard as I thought?

 

[begreen]

Fiber bristle. Get at least one rod longer

 

[newatthis]

Is that because the steel bristle is too hard on the flue, begreen?

 

[begreen]

Yes. It might tear the liner.

 

[jatoxico]

Newatthis, just an FYI. I don't know if you ever heard of the Soot Eater but it's a system that uses a power drill and rotating head. With it you can do a cleaning from the bottom up. Like everything there are pros and cons but thought I would mention it.

* basic kit comes with 18' of rod. I had to buy another rod kit to get to the top of my cap.