Help with understanding the Jotul Oslo High Flow Combustor Technology

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.

dvellone

Feeling the Heat
Sep 21, 2006
484
I used to run a Consolidated Dutchwest with a cat - which gave me a bad taste for cats - and I've been heating with a Castine for the past dozen years.

I was looking at the Oslo last year, but not ready to purchase, and in the meantime I understand the design incorporated " high flow combustor technology", which is warranted for 20 years.

Can someone help me understand how this differs from the old ceramic cat design Consolidated helped me to dislike, and how (and if) it differs from my Castine?

Thanks, Daniel
 

Highbeam

Minister of Fire
Dec 28, 2006
19,173
Mt. Rainier Foothills, WA
Just because it is warranted for 20 years does not mean it will last 20 years. You should expect normal life of 10-12k hours that even the best hybrid cat stove manufacturers are able to get. That only takes 20 years if you burn occasionally.

I like cat stoves that are designed well to allow a wide range of burn outputs. Many of these new 2020 cat additions were done to solve an emissions problem so you get the cat drawbacks without the cat benefits.

The jotul is very new so we’re still seeing.
 

dvellone

Feeling the Heat
Sep 21, 2006
484
Just because it is warranted for 20 years does not mean it will last 20 years. You should expect normal life of 10-12k hours that even the best hybrid cat stove manufacturers are able to get. That only takes 20 years if you burn occasionally.

I like cat stoves that are designed well to allow a wide range of burn outputs. Many of these new 2020 cat additions were done to solve an emissions problem so you get the cat drawbacks without the cat benefits.

The jotul is very new so we’re still seeing.
No tubes anymore, or is it a modified design that incorporates a cat? Having some trouble finding a good explanation of the actual design.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
There is a tiered, stainless secondary rack under the baffle. It's a hybrid with a full-width cat cleaning up as an afterburner. Jotul calls this Fusion combustion. This video provides a good illustration of the parts.

 
  • Like
Reactions: dvellone and mar13

dvellone

Feeling the Heat
Sep 21, 2006
484
There is a tiered, stainless secondary rack under the baffle. It's a hybrid with a full-width cat cleaning up as an afterburner. Jotul calls this Fusion combustion. This video provides a good illustration of the parts.

The new stepped baffle design looks like the baffle in my Castine. So, if I'm understanding this design, it's still using the baffle for secondary combustion, but added the cat for a more thorough burn of all the secondary gasses? Does that seem correct?
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
Yes, this is not much different from other hybrids except that Jotul chose to eliminate the complexities of a bypass mechanism by using an oversized, special catalyst.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,173
Mt. Rainier Foothills, WA
Yes, this is not much different from other hybrids except that Jotul chose to eliminate the complexities of a bypass mechanism by using an oversized, special catalyst.

Complexities in construction and operation. I also believe that it’s a compliance measure that really isn’t intended to last. Meaning, replacement is unlikely since nobody would notice.
 

dvellone

Feeling the Heat
Sep 21, 2006
484
Complexities in construction and operation. I also believe that it’s a compliance measure that really isn’t intended to last. Meaning, replacement is unlikely since nobody would notice.
This sort of gets to the crux of what I'm wondering: other than the addition of the cat, and baffle modifications aside, I'm wondering if the new Oslo will essentially perform like the pre-cat design. In other words, if you take away the cat do you still have the performance of the pre modified Oslo.
But, don't get me wrong, I'm all for improvements in terms of reducing pollutants, just curious to what extent the cat may have (or not) replaced the original design's efficiency, or if it's just an addition to the efficiency.
Thanks
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
Complexities in construction and operation. I also believe that it’s a compliance measure that really isn’t intended to last. Meaning, replacement is unlikely since nobody would notice.
Could be. FWIW, this could be said of most cat stoves. It wouldn't surprise me if over half the owners never change the cat.
 
  • Like
Reactions: bholler

Highbeam

Minister of Fire
Dec 28, 2006
19,173
Mt. Rainier Foothills, WA
Could be. FWIW, this could be said of most cat stoves. It wouldn't surprise me if over half the owners never change the cat.

I think this one is different. This is a fully functional noncat stove that will do everything the operator wants and act like new even with a dead cat. The operator will probably never even notice the dead cat because the noncat portion of the combustion package does almost everything.

The regular cat stoves, when the cat dies, are very noticeably crippled. Huge smoke, dripping tar, low heat, high wood consumption. Sure it’s possible to burn this way but much harder to do it “accidentally” . Oh and the cat clogs which really is noticeable.

I don’t know that there is a solution or a real problem. This particular design at 67% efficiency, with no bypass, and huge cells, on top of a fully functional noncat is just almost just like a joke to the epa. Like taunting them. I hope it doesn’t backfire on the industry.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,641
central pa
I think this one is different. This is a fully functional noncat stove that will do everything the operator wants and act like new even with a dead cat. The operator will probably never even notice the dead cat because the noncat portion of the combustion package does almost everything.

The regular cat stoves, when the cat dies, are very noticeably crippled. Huge smoke, dripping tar, low heat, high wood consumption. Sure it’s possible to burn this way but much harder to do it “accidentally” . Oh and the cat clogs which really is noticeable.

I don’t know that there is a solution or a real problem. This particular design at 67% efficiency, with no bypass, and huge cells, on top of a fully functional noncat is just almost just like a joke to the epa. Like taunting them. I hope it doesn’t backfire on the industry.
Do you know it will work just like a regular non cat? Or is that just an assumption? And I agree with bg the majority of cat stoves I work on never have the cat changed and many have no cat.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
The situation described is likely common with most hybrid stoves.
 
  • Like
Reactions: Highbeam

Khelindros

New Member
Sep 15, 2021
1
North Dakota
I think this one is different. This is a fully functional noncat stove that will do everything the operator wants and act like new even with a dead cat. The operator will probably never even notice the dead cat because the noncat portion of the combustion package does almost everything.

The regular cat stoves, when the cat dies, are very noticeably crippled. Huge smoke, dripping tar, low heat, high wood consumption. Sure it’s possible to burn this way but much harder to do it “accidentally” . Oh and the cat clogs which really is noticeable.

I don’t know that there is a solution or a real problem. This particular design at 67% efficiency, with no bypass, and huge cells, on top of a fully functional noncat is just almost just like a joke to the epa. Like taunting them. I hope it doesn’t backfire on the industry.

I am pretty new to stoves and cats in general. What I am gathering from the discussion here is that the stove would run and likely run well if its combustor was simply removed. Am I reading the situation right here or am I way off?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,641
central pa
I am pretty new to stoves and cats in general. What I am gathering from the discussion here is that the stove would run and likely run well if its combustor was simply removed. Am I reading the situation right here or am I way off?
We have no idea how it will run without a cat in place. But I have heard quite a few reports of very early cat failures. Jotul says it was due to out of spec parts.
 
  • Like
Reactions: Khelindros

Highbeam

Minister of Fire
Dec 28, 2006
19,173
Mt. Rainier Foothills, WA
I am pretty new to stoves and cats in general. What I am gathering from the discussion here is that the stove would run and likely run well if its combustor was simply removed. Am I reading the situation right here or am I way off?

That’s going to depend on the particular stove and how good the primary and secondary combustion system is. If those systems got the design 98% to passing the emissions test then the cat they added to get to 100% will never be missed.

There are so many very good cat stoves out there that take advantage of the catalyst to do things that couldn’t be done otherwise like very long clean burns at low output. That’s a great thing and if you can’t use it then seek out a noncat.
 
  • Like
Reactions: Khelindros

Todd

Minister of Fire
Nov 19, 2005
9,407
NW Wisconsin
Looks like this design has no cat guard to prevent flame impingement, similar to the Lopi Cape Cod which also had cat issues.

I’m surprised Jotul didn’t do the same thing to the F45/55 to eek out a little more efficiency to get that tax credit.
 

Sailrmike

Feeling the Heat
Sep 20, 2017
278
06371
Looks like this design has no cat guard to prevent flame impingement, similar to the Lopi Cape Cod which also had cat issues.

I’m surprised Jotul didn’t do the same thing to the F45/55 to eek out a little more efficiency to get that tax credit.
IMHO they did as little as possible to meet emissions standards only. Does anyone know the difference in efficiencies between Oslo V2 and V3? I can't recall
 

EbS-P

Minister of Fire
Jan 19, 2019
1,252
SE North Carolina
I’m surprised Jotul didn’t do the same thing to the F45/55 to eek out a little more efficiency to get that tax credit.
My personal opinion is I think there R&D for 2020 regs is really under resourced. Selling a total of 4 wood fired products, down from maybe 10 and no insert. I love my F400. Sad that I can’t recommend it.