DIY turbulator anyone?

[EbS-P]

So I’m considering a DIY turbulator.
What is it?
See Jotuls diagram #73. It’s a structure that increases turbulence above the baffle to increase heat transfer to the stove top.
Why?
I’m trying to dial in a self diagnosed over drafting insert. It has a damper but I’m still not convinced it’s operating at peak efficiency. That stoves will be detailed in an another thread.

If Jotul thinks it’s worth it, is it worth try to make one myself? What would you use? I have about 2.5” of space above the baffle.

My thoughts are 2” tall pieces of 3/4” or 1” angle iron maybe 5-8 of them standing up on end on top of the baffle? If it’s this simple why doesn’t every stove have them?

 

[TomMcDonald]

I thought you were talking about one of these.

 

[Poindexter]

Microfins for air management are allowed in a few classes of hydroplane boat racing. They typically show up under the bow to direct airflow under the hull between the sponsons. I think they are pretty common on the Boeing 737 also, on top of the wing near the leading edge.

You should ask a physics professor, this is complex math. Smiley. Microfins are specifically prohibited on boats planning to compete in the Yukon 800 race.

Good luck and best wishes.

 

[ABMax24]

I'll try to remember to take a picture of what I've built for my stove. For me it's helped both with the overdraft issue, and helped to spread the heat to the back corners of the stove.

It does something like this, don't mind the low budget Paint sketch. This would be a top down view, with the stove pipe as the circle and the front of the stove is at the bottom.

 

[EbS-P]

I'll try to remember to take a picture of what I've built for my stove. For me it's helped both with the overdraft issue, and helped to spread the heat to the back corners of the stove.

It does something like this, don't mind the low budget Paint sketch. This would be a top down view, with the stove pipe as the circle and the front of the stove is at the bottom.

View attachment 305620

So the 2020 1800 has a deflector with angled wings, unlike your right angles and it’s placed in the front 2/3.

Microfins for air management are allowed in a few classes of hydroplane boat racing. They typically show up under the bow to direct airflow under the hull between the sponsons. I think they are pretty common on the Boeing 737 also, on top of the wing near the leading edge.

You should ask a physics professor, this is complex math. Smiley. Microfins are specifically prohibited on boats planning to compete in the Yukon 800 race.

Good luck and best wishes.

Vortex generators on boats that’s new to me.

I will in my free time build and runs a 2d fluid dynamics flow model. Yeah no…. I’ll just chop one angle iron

 

[SpaceBus]

Is there room for another pipe damper? Correct me if I'm wrong, but this is a basement stove with a really tall chimney. I think reducing draft would be the better approach for this stove.

 

[EbS-P]

Is there room for another pipe damper? Correct me if I'm wrong, but this is a basement stove with a really tall chimney. I think reducing draft would be the better approach for this stove.

No room for another damper. Flue temps on full re load spike at 900 at the collar. Burn visually looks ok. It will settle down at 750 for a good bit. Stove top temps can be managed with the blower to stay under 600. But I feel that the flue temps should be closer to stove top.

 

[moresnow]

Have you altered the standard pipe damper by closing off some of the openings? Easy way to get to your intended result.

 

[ABMax24]

So the 2020 1800 has a deflector with angled wings, unlike your right angles and it’s placed in the front 2/3.

Yes my 2015 model also has the angled deflector welded to the stove top.

The piece I built isn't square, it's front edges are angled at a 45, I'm just not great at drawing in paint, I'm better at CAD.

I'll try to take a picture when I can cool the stove off, but the thermometer is bouncing off -40 today, might have to be after Christmas.

Prior to this I did use pieces of angle iron sitting on top of the baffle, even those seemed to help and is what led my to this design.

 

[Woodcutter Tom]

This is what my Escape 1500 looks like under the stove top. The deflector is toward the front of the stove. I imagine your 1800 is similar. Perhaps enhancing this someway will slow the air.
I run my damper nearly completely closed when I am settled in. About .05 "WC.
I had 900 F at 18" above stove top just now on this morning's restart. No big deal to me.
I have seen people discuss flue and STT being very close to each other. I have yet to see that on my stove. Flue is 200 more when STT is high ....600 F.

 

[EbS-P]

Yes my 2015 model also has the angled deflector welded to the stove top.

The piece I built isn't square, it's front edges are angled at a 45, I'm just not great at drawing in paint, I'm better at CAD.

I'll try to take a picture when I can cool the stove off, but the thermometer is bouncing off -40 today, might have to be after Christmas.

Prior to this I did use pieces of angle iron sitting on top of the baffle, even those seemed to help and is what led my to this design.

So is yours behind the stock deflector or in front

 

[mellow]

This is a long shot if you can still find them, but Dovre stoves had something like this that was put on the stoves exit, not sure if you could work with that or not.

Old thread on it: https://www.hearth.com/talk/threads/dovre-300h-woodburning-stove.53357/post-675615

Sure enough, woodsmans still has the baffle: https://www.woodmanspartsplus.com/product/ConsolidatedDutchwestBaffle612

 

[ABMax24]

So is yours behind the stock deflector or in front

Behind the stock deflector.

It sits about 1/4" in front of the opening for the flue.

 

[Todd]

What about a piece of expanded metal? I remember my old Fireview and Keystone both had expanding metal in front of the cat to create turbulence.

 

[mikey]

My Jotul 602 has those deflectors on the top front edge of the baffle plate, as far as I know it was the only thing that improved the 602cb and my 602 v2 the cb did not pass the 2020 standards the v2 does. It’s amazing how a small modification can make such a large impact.

 

[begreen]

Ironstrike's Montlake stoves have had turbulators for a long time. They also have similar thermal fins on the top of the stove under the convection lid for greater heat transference.

 

[EbS-P]

At this point I could further block the damper but I think it’s running ok (I will add a magnahelic gauge at some point. ) based on flame patterns. At this point I just want to see if creating more turbulence above the baffle has any effect. (Smoke spillage when opening the door with the damper closed or near closed is considerable. ).

What about a piece of expanded metal? I remember my old Fireview and Keystone both had expanding metal in front of the cat to create turbulence.

probably more important as a flame shield.

 

[ABMax24]

FWIW this is the picture of mine above the baffle, cool enough to get this pick but wasn't going to pull the baffle out. I keep meaning to build a nicer one, because this is a different revisions cur apart and welded together but it does the job. The "legs" on the bottom are for spacing, and allow me to push it up against the back of the stove. I did have to cut the big notches out of the back, because smoke spillage was an issue.

 

[begreen]

How does one measure the effectiveness?

 

[ABMax24]

How does one measure the effectiveness?

My definition?

Lower temperature delta between the stove top and flue temps, ie the temperatures are closer together meaning more heat is transferred to the stove top.
The rear corners of my stove are hotter, on average 75F hotter, meaning that part of the stove is absorbing more heat from the gases, allowing it to be transferred to the room. All verified with the same IR temp gun. The stove top also has a more even temperature, cooler in the center hotspot, and warmer everywhere else.
Lower average flue temps. It's impossible to make a 2 identical runs back to back, but over a series of runs the flue temps are cooler, on average 50F-75F cooler, backed up by a K-Type thermocouple on a digital multimeter.
Increased controllability. (I'm an extreme overdraft case, so this may be a detriment to most). Restriction in the flue path, has opened the operating range of the stove damper, common operating range is 10%-60%, where it used to be 0% to 35%. Less sensitive to exact position on the flue damper, gives me a little more room for error and still have the stove operate acceptably.

 

[ABMax24]

Just went and checked my stove, its been digesting 4 pieces of birch for the last 45 minutes now, that were loaded onto pine coals.

Flue temp (measured with the above mentioned K-Type): 580F
Center of stove top: 740F
Everywhere else I can measure on the stove top (keep in mind the Matrix has a large top jacket plate, so only what I can see by removing the soap stones) was 550F or greater, much of it though was over 600F.
Back corners of the stove, 380F.
All this with blower running on max.

I'm happy with this, I'm sure the BK guys would scoff at those flue temps, but this stove is also throwing some serious heat right now. Going to be knocking on the door of -40 again tonight.

 

[EbS-P]

Well I hacked up some angle iron and had a burn today. Not enough time to do it well. I laid an 6” piece on edge in front of the the stick deflector.

Observations. Flame path looked different but it could have been the longer NS log on the left. Also the turbulence was observable earlier in the burn. But the two taller pieces looked more effective than the shorter ones. Maybe the center temp was closer to the 1/4and 3/4 positions on the top. No noticeable difference in the flue temps.

Time will tell if it made ant difference.

 

[begreen]

I'm not disputing the results, but could the heat gained be due to the longer residence time of the flue gases rather than more complete combustion due to increased turbulence? Or maybe both? This requires instrumentation of the flue gases to determine.

 

[vbu]

After following this thread I decided to give this a shot as well. I can see the bar that connects the liner to the insert (the one in the direct path of flue gasses) glow red regurarly. No telling what the flue gas temps are. Hopefully this will allow the flue gasses to stay in the stove a little longer instead of going straight up the flue, cooling them down some. I cut this from a scrap piece of metal I had laying around
Some pics. It was kinda hard to take pics with it in place, but you get the idea. Haven't tried it yet, just put it in after replacing the ceramic blanket after a squirrel tore up the other blanket