# Jotul 118 cleaning out ash.



## Jotul118 (Dec 5, 2013)

The bottom of my Jotul 118 has wavy ridges to allow for a better burn. Does anyone have any advice on how often I should clean and is there some sort of tool that I can push back the ashes for a new burn. I had a bit of a fiasco yesterday between my first chimney clean and ash removal.

On that note, are ash vacuums just a gimmick or should I get one? My shop vacuums clogged but I've heard they will retain proper suction if they have a special filter? Just trying to refine my servicing processes moving forward because yesterday it seemed like it took an eternity to get the jobs done.


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## Fort Wisers (Dec 6, 2013)

We've been heating a small cabin with the newer version of your stove (F118CB Black Bear) for a little over a year now.
I've always left about 1"-2" of ash on the bottom.......
As for cleaning ashes out, I do the following, both at the cabin and at home (we heat both 100% with wood):

I just use a small ash shovel and a scuttle, I take a few shovel fulls out each time I load the stove and place them in the scuttle, which I then place outside away from anything combustable.
I basically take as many ashes from the front of the stove that I can with-out reomving coals.
I then rake coals into the "hole" created from ash removal.....then I load the stove.
After a few days, when the scuttle is getting full, later I'll dump the scuttle of ashs into our fire pit.
Once you get used to it, dealing with the ashes is actually a pretty painless job and can be kept relatively clean.

Hope that helps.....


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## Jotul118 (Dec 6, 2013)

Fort Wisers said:


> We've been heating a small cabin with the newer version of your stove (F118CB Black Bear) for a little over a year now.
> I've always left about 1"-2" of ash on the bottom.......
> As for cleaning ashes out, I do the following, both at the cabin and at home (we heat both 100% with wood):
> 
> ...


Very good suggestions! Very much appreciate! Question though..how does one clean the ashes out of those wavy grooves that assist with air flow and a better burn? Is there a tool out there for that? I'm taking it that it is a Jotul design thing?


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## Fort Wisers (Dec 6, 2013)

Jotul118 said:


> Very good suggestions! Very much appreciate! Question though..how does one clean the ashes out of those wavy grooves that assist with air flow and a better burn? Is there a tool out there for that? I'm taking it that it is a Jotul design thing?


 Personally I've never bothered but I guess you could wait until your stove is bone cold (like maybe in the summer), shovel what you can and then vacuum the rest?
Not sure, I've always run mine with some ash on the bottom to help retain a coal bed.
I honestly can't say how the system would run without any sort of ash bed.
Maybe someone else on this forum with the same stove has a different idea?
I think it is a Jotul thing as most other stoves have a firebrick lined bottom.....


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## Jotul118 (Dec 6, 2013)

Fort Wisers said:


> Personally I've never bothered but I guess you could wait until your stove is bone cold (like maybe in the summer), shovel what you can and then vacuum the rest?
> Not sure, I've always run mine with some ash on the bottom to help retain a coal bed.
> I honestly can't say how the system would run without any sort of ash bed.
> Maybe someone else on this forum with the same stove has a different idea?
> I think it is a Jotul thing as most other stoves have a firebrick lined bottom.....


 
I was doing it the same way, but over Thanksgiving I was talking to my brother (the engineer), and he said that the grooves allow the incoming air to wrap around to aid in best combustion toward the slow cigar burn. I pushed the ash toward the back exposing more of the grooves and it seemed to really get and keep the fire burning more efficiently. I was able to dial down both the air inlet and damper and maintained the same stack temperature as before when the air inlet and damper were both more open.

I found an interesting read putting the 118 and a un-baffled equivalent to the test burning in like structures.

In designing wood stoves it is important to remember that the completeness of combustion will be determined largely by the arrangement of the draft system. Efficiency demands two drafts - one to feed primary air to the coals for maintaining the basic fire, and another to admit secondary air to the region above the coals for the combustion of unburned volatile substances in the smoke. Ideally, both primary and secondary air should be preheated before entering the firebox, and both draft systems should be either independently adjustable or else preproportioned, so that the proper ratio of primary to secondary air can be maintained.
We should also remember that heat-transfer efficiency is increased by forcing the smoke to pass closer to the stove's surface on the way to the flue or by forcing it to take a longer path. Baffles, cooling fins, heat-exchange chambers, convection tubes and forced-air plenums are all worth considering when the stove is being designed. Often a fairly simple structural modification can result in a significant increase in heat-transfer efficiency.
The Jøtul company has published some interesting data on the comparative performance of wood stoves with and without these efficiency-promoting features. In an experiment conducted independently in Canada, two cast-iron stoves were installed in identical camp buildings 1-1/2 miles apart. One of the test units was a conventional box stove with neither baffle nor provision for secondary air (Figure 14.2). Airflow from the draft to the flue is





*Figure 14.2 - Cross-section of a typical unbaffled cast-iron box stove. Airflow from the draft to the flue is direct, and there is no provision for secondary combustion of the smoke.*
direct, and smoke may rush up the stovepipe unburned. The other was the Jøtul No. 118. The Jøtul incorporates a horizontal baffle that forces the smoke to travel toward the front of the stove and then through a top-mounted heat-exchange box before reaching the stovepipe (Figure 14.3). It also features a hollow door with asingle draft control on the outside and two ports on the inner surface. The air is preheated in the door cavity and then passes into the firebox through a primary draft near the coals and a proportionately-sized secondary draft higher up. This design is intended to promote complete combustion of the smoke just as it enters the heat-exchange box.




*Figure 14.3 - Cross-section of the Jøtul No. 118 wood stove, distributed in the U.S. by Kristia Associates. Incoming air is preheated within the hollow door and divided into primary and secondary streams. Wood burns from front to back. Secondary combustion takes place as smoke is entering upper chamber.*
Throughout the experiment, office clerks in both camp buildings kept careful records of indoor and outdoor temperatures and of the amounts and types of wood used. Although both buildings were maintained at essentially the same temperature and burned about the same proportions of hardwood and softwood, the standard box stove consumed 8.53 cubic feet of wood per day, compared to 4.25 cubic feet per day for the Jøtul No. 118. In other words, the conventional stove required about two cords of wood to produce the useful heat that the baffled stove squeezed out of one cord. And there was another notable difference:
The conventional stove was usually dead by 2:00 a.m., so that indoor temperatures often fell into the 20's by morning, while the Jøtul always held enough coals to start dry wood in the morning, and the indoor temperatures on corresponding days never dropped below 40. Anybody with a little training can pick out some unfortunate flaws in the design of this experiment, but on the basis of experience with both baffled and unbaffled stoves, I find these results entirely believable.
The above experiment was comparative only - it measured the relative efficiencies of the two stoves. The Jøtul company's engineering department has conducted other tests that shed some light on the interesting problem of absolute efficiency. Figure 14.4 shows the results of tests conducted on the same model stove used in the Canadian experiment. Notice that the overall efficiency starts relatively low, rises to a peak of 76 percent, and then declines as the firing rate is progressively increased.
I would guess that the efficiency is low at low firing rates because the stove is relatively cool, so that the smoke is below its kindjing temperature by the time it reaches the zone of secondary combustion, and leaves the stove unburned. At somewhat higher firing rates, everything works as it should, and the gases are more completely burned. When the stove is opened up still further, airflow through the unit is probably so rapid that the hot gases escape to the flue before they have had time to yield their heat to the metal, so that efficiency once more falls off. At the maximum firing rate, the overall efficiency is a shade under 55 percent.
This experiment demonstrates that the efficiency of a wood stove cannot be expressed as a single number, because it dependsso much on how the unit is used. In the previous experiment we learned that efficiency also depends heavily on how the stove is built. In the next chapter we'll plunge into stove design. If you are especially interested in efficiency, you might pay particular attention to the sections on drafts, baffles, and heat-transfer systems.




*Figure 14.4 - Graph illustrating manufacturer's test results on Jøtul No. 118 shows the absolute efficiency. Overall efficiency starts low, rises to a peak of 76 percent and then declines as the firing rate increases.*


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## Fort Wisers (Dec 6, 2013)

Hummmm very interesting....I just went through all the documents that came with my Black Bear and I don't see anything mentioned about needing to keep the bottom section cleared.
My stove (being EPA rated) has a baffle and secondary burn system.
I have since modifed the baffle for reasons I won't get into here.
BUT, I'm going up to the cabin this weekend (and it's supposed to be fairly cold) so I might just try and empty out the ash and see how it works like that.
If that is the case, I ca see why keeping the ash cleared right out has become such a chore......


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## Jotul118 (Dec 6, 2013)

Fort Wisers said:


> Hummmm very interesting....I just went through all the documents that came with my Black Bear and I don't see anything mentioned about needing to keep the bottom section cleared.
> My stove (being EPA rated) has a baffle and secondary burn system.
> I have since modifed the baffle for reasons I won't get into here.
> BUT, I'm going up to the cabin this weekend (and it's supposed to be fairly cold) so I might just try and empty out the ash and see how it works like that.
> If that is the case, I ca see why keeping the ash cleared right out has become such a chore......


Please, by all means, let me know your thoughts when you return. I am also trying to find a clean out tool (if it exhists) for the purpose of keeping that channel from getting too dense in ash matter.

Enjoy your weekend!


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## Jotul118 (Dec 6, 2013)

*


Fort Wisers said:



			Hummmm very interesting....I just went through all the documents that came with my Black Bear and I don't see anything mentioned about needing to keep the bottom section cleared.
My stove (being EPA rated) has a baffle and secondary burn system.
I have since modifed the baffle for reasons I won't get into here.
BUT, I'm going up to the cabin this weekend (and it's supposed to be fairly cold) so I might just try and empty out the ash and see how it works like that.
If that is the case, I ca see why keeping the ash cleared right out has become such a chore......
		
Click to expand...

 *
Just found some interesting food for thought on an old thread in here.

For what it's worth, an original owner of a 1973 Jotul 118 has told me that the bottom plate with wavy ridges on his stove is held on with bolts at the corners (like Mike's) and there is no space with insulation under it. He says the manual that came with the stove calls for two inches of sand on the bottom. I think one function of the wavy ridges is to preserve the sand layer when shoveling out ashes.

It makes sense to me. Weather it's ash or sand should be fine I would think. I misunderstood my brother by the way. I believe he was talking about the area in front of the air inlet being freed up for the draft to do its thing.

I think I will be more at ease not having to clean out that area too often.

The ridges must just be an edged guide for the ash shovel to travel across, thus leaving the area of sand intact. Very interesting and I'm guessing the designer was just using creative license.


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## cuttingedge (Dec 7, 2013)

Jotul118 said:


> Just found some interesting food for thought on an old thread in here.
> 
> For what it's worth, an original owner of a 1973 Jotul 118 has told me that the bottom plate with wavy ridges on his stove is held on with bolts at the corners (like Mike's) and there is no space with insulation under it. He says the manual that came with the stove calls for two inches of sand on the bottom. I think one function of the wavy ridges is to preserve the sand layer when shoveling out ashes.
> 
> ...




My Cawley/ Lemay 600 has the same design and it too calls for a 1"-2" layer of sand or ash on the bottom. I think that this is to preserve coals as well as to protect the bottom.


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## begreen (Dec 8, 2013)

A good bed of ash or sand also insulates the fire from the base. This helps the fire burn hotter and keeps the hearth from overheating.


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## Fort Wisers (Dec 10, 2013)

I'm going to have to agree with BG on this one....when we got to camp this weekend I emptied the stove entirely of ash (it needed a good cleanout anyhow so it was a perfect time to trial).
I found that the bottom of the stove (and thus the floor underneath) got much hotter than I could previously remember.
So I let a good ash build up form and ran it this way for the rest of the weekend.
I think the waves are there to ensure there's a bit of a ash bed preserved at the bottom.....
I also can't see any practical way of keeping the stove 100% cleaned out of ashes and I don't believe it would hold a coal bed nearly as well..
Since there is no fire brick on the bottom of this stove I actually don't feel comfortable running it with out some sort of ash or sand bed at the bottom.


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## Jotul118 (Dec 10, 2013)

Fort Wisers said:


> I'm going to have to agree with BG on this one....when we got to camp this weekend I emptied the stove entirely of ash (it needed a good cleanout anyhow so it was a perfect time to trial).
> I found that the bottom of the stove (and thus the floor underneath) got much hotter than I could previously remember.
> So I let a good ash build up form and ran it this way for the rest of the weekend.
> I think the waves are there to ensure there's a bit of a ash bed preserved at the bottom.....
> ...


I was hoping you would see my response to you before you headed out to your camp. I found an older thread talking about the 118 and the reason for the ridges.
I love learning things! Just got in from cutting down a Norway Spruce for our camps Xmas tree and the Jotul is coming up to cruising heat.

Hope you all have a great holiday season!


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## Fort Wisers (Dec 12, 2013)

Jotul118 said:


> I was hoping you would see my response to you before you headed out to your camp. I found an older thread talking about the 118 and the reason for the ridges.
> I love learning things! Just got in from cutting down a Norway Spruce for our camps Xmas tree and the Jotul is coming up to cruising heat.
> 
> Hope you all have a great holiday season!


 
We cut a small tree while at camp for the kids to decorate....
We make this trip every year and it has become sort of a pre-Christmas-Christmas for us LOL
Always good fun to go out into he bush, work a little then come back to a nice warm stove!
Take care and enjoy the holiday season as well.....


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