Turbulator II: Chain Test Tonight

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Nofossil

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I'll be running another test burn tonight with chains instead of my normal turbulators.

The chains I have are probably a bit smaller than ideal. My HX tubes are about 1 7/8" ID, and the chain links are about 1 1/4" wide.

Any brave souls want to make predictions about flue temps? We have two data points. These are averages over approximately 90 minutes of steady burn at 1200 degree combustion. Combustion temp is measured in the secondary combustion chamber downstream and around a baffle from the active flame area. Flue temp is in the center of the flue right at the outlet of the boiler.

Flue temp with spiral metal turbulators: 495
Flue temp with *no* turbulators: 549
 
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What's the attraction of chains vs. oem? Easier to remove?
For me, mostly curiosity. They would be easier to remove, but I already have the spiral versions made up. Lots of folks use chains, and I'm curious about the relative performance.

For my system with its short HX tubes, the spiral turbulators drop flue temps by a bit more than 50::F. I'm just curious to see how the chains compare. I kind of hope that they're comparable.
 
What's the attraction of chains vs. oem? Easier to remove?
The attraction simply was my Tarm of 2006 did not have turbulators, I had excessive flue temps, and after researching turbulators, having a very good length of chain on hand, I gave the chains a try. Solved my problem.

For others it may be lack of experience, knowledge or a severe burning mistake and end up with creosote in the fire tubes and a real clean-up mess, including stuck turbs. Hate to admit it, even for me and my first burn of this season was with wood that was much wetter than I thought. Glad I had the chain turbs.
 
I used 3/8" chain for a while,I thought they were to restrictive.
Seems I really had to open up the air to burn nice.
Ended up putting the originals back in.
So I would guess they will drop the flue temp more than the spirals.
It would be interesting to see how the spring type like the Froling uses compare.
 
I ran without last night , flue temp got as high as 590f . This morning I put my 3/8 chain turbs back in and the temps are hovering between 400 and 450.
Fan speed was 60% ... no modulating..

IMHO the chain turbs work great
 
I just thought the spiraled ribbon turbs and all that mechanical claptrap was a joke. They could have taken the cost of that useless mess and put it in other improvements or the profit column. When I actually became tired of fooling with that mechanism in order to brush the tubes and found myself postponing the chore because I didn't want to look like a coal miner after a days work I decided to remove all of it.

I monitored the flue temps. with the original vs the chains and found no significant difference in temperature so I went with the chains for ease of handling. They do get a fly ash build-up but dropping them about 4 feet on to concrete cleans them nicely
 
My guess 470F
 
So - here's the numbers:

Average combustion temperature, with turbulators: 1202.2
Average flue temperature, with turbulators: 494.6

Average combustion temperature, w/o turbulators: 1200.5
Average flue temperature, w/o turbulators: 549.0

Average combustion temperature, with chains: 1198.9
Average flue temperature, with chains: 503.2

The chains do surprisingly well, especially given that they're smaller than conventional wisdom suggests. One way of looking at it is that the spiral turbulators recover about 15% of the waste heat from the flue gas, and the chains recover 13%.

Love to find some larger chain.

chains.png
 
I wonder if different boilers have greater potential efficiency limits by virtue of their different heat exchanger designs.

My Tarm 40K has more, longer and larger diameter (3.2") firetubes than a 25K. Is this a greater opportunity to capture back more heat from going up the chimney than smaller (or simply different) heat exchanger designs. I'm pondering a perhaps greater proportion of the heat, not just more heat because it's bigger all around.

I don't have a clue on this, just curious.
 
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