Starting a new thread for this so it doesn’t get buried deep in my conversation with @billc
I had a good setup for chaff collection from the cooling tray with the exhaust adapter and mesh bag but my wife wasn’t stoked on the chaff that I indiscriminately blew out of the roof vent into our backyard lol so I’ve been on the recent quest to keep things cleaner and more chaff free.
My build is based on @billccart thread. I’m on my third version of arrangement and this one is the best so far but I’m still having issues with the last bit of chaff being blown out of the Bullet exhause during cooling.
Suction and airflow from my 4" Vivosun inline blower is sufficient during the entire roast to collect chaff and send the smoke up the chimney to the outside world. My challenge is when cooling begins. I assumed that between the inline fan, the cooling tray fan, and the increased speed of the exhaust fan they would together provide more than enough airflow to send all the smoke and chaff through the system. My assumption was wrong. It’s almost like there’s backflow happening during cooling from the Bullet exhaust and so there’s a small puff of initial smoke, and a small amount of chaff escaping during cooling.
I’d love any insights or advice from folks who have solved this issue before! Thanks!
I like what you did with the exhaust adapter. Getting it closer tot he exhaust port of the Bullet.
I assume that the “smoke and chaff burp” is coming out of the exhaust of the bullet?
I am just guessing but I think that a likely culprit will be the reduction from 4 inch duct down to 2 1/2 inch hose after the Vivosun fan.
Amazon sells a 4 inch cyclone kit that might help for around $22.00
I don’t know if the 4 inch kit will work with a standard 5 gallon bucket.
Perhaps a way of checking to see if the duct reduction is the cause would be to hook a 4 inch dryer hose between the Vivosun and the rigid duct going up through the ceiling and bypass your existing cyclone filter.
Run a single roast (when you are home alone ) and see if you still get the “burp”
Thanks as always for engaging your brain. You are correct that’s where the burp comes from. However, I think it’s an issue with CFM and flow. I’m roasting a pretty chaffy coffee this morning and everything is very clean until FC hits and now the exhaust can’t keep up with the chaff. I’m vacuuming a pile of it from my counter while the roast cools.
I actually bought that exact kit at first and cut holes into a bucket lid to see how that would work but liked the cyclone lid you posted better. Maybe I’ll swap them out and see if that solves my problem. I guess I was naive to how airflow actually works and assumed stepping down from a 4" duct > 3" > 2" would increase flow not restrict it.
Well, this is interesting. I thought you were only seeing the burp when the bullet went into cooling mode.
Do you still have the stainless screen filter in the bullet? I assume that you removed it
otherwise there would be no chaff exiting the Bullet.
My original thought was: with the cooling tray fan (C) ramping up to full speed and the exhaust fan ramping up to full speed that there was a short term reversal of the air flow due to the duct size reduction which caused the burp. Then once the air flow resumed the chaff and smoke exited as expected.
I wonder if anything would change if you moved the fan after the cyclone.
Nope that’s been long gone as you assumed. So here’s what I’m gonna try for my next step because this Bali Kintamani is super chaffy and smokey as you already know and this setup can’t keep up with the smoke even post-FC.
I’m going to install a 4" system throughout and see if that was my issue all along. If that still doesn’t work then I’ll move the fan to after the cyclone and see if that helps.
With my setup, I don’t get any smoke in the house unless I accidently bump the rheostat for the vacuum speed and it gets reduced. I typically run the shop vac at about 60% of full power. I don’t change the vac speed during roasts. In the beginning I did, but I have found that it doesn’t make any difference.
If I forget and don’t turn on the Shop vac before starting the Bullet, I will get a little puff of chaff out of the exhaust port of the Bullet.
Cleaned it up even further and transitioned to all 4" ducting. Roasting a test batch now. Discovered all the smoke issues were related to a clogged exhaust fan in the Bullet with chaff. Because I made the alteration to the propeller this happens sometimes when the airflow on the backend is restricted. Because the Vivosun wasn’t pulling as much as I needed I wasn’t actually sucking out all the chaff that was being expelled. Clogged the fan and wasn’t able to evacuate the smoke out effectively.
Did you remove every other fan blade? I found the fan blades were too close together and the Bullet exhaust fan would clog. So I removed every other blade. That made a huge difference.
There is a reference to the blade removal in the original post and a couple of photos.
Thinking a little more: In my setup the vacuum is after the cyclone, so no chaff goes through the shop vac. All of the chaff gets caught by the cyclone.
I think that you are getting close.
Worst case: How hard would it be to put the Vivosun after the cyclone?
Yep, that’s exactly what I did with the fan blade. I could move it if the chaff passing through it becomes an issue but after three roasts on the new setup I think I may have finally cracked the code. No smoke burps. Very little chaff escaping during roasting. and no smoke/chaff escaping during cooling at all.
I think the only thing that I need to see about now is that with the 4" size kit for the cyclone elbows in the bucket I think the outlet is catching some of the chaff being collected and spewing it out of the roof again. It’s definitely not near as much but I noticed some floating outside my garage during the cooling phase.
I thought about placing a screen or something on the outlet of the bucket but I don’t want to restrict airflow and install a possible clog/choke point down the road.
Welp… I thought I finally had a design that was smoke free, chaff free and trouble free. I was wrong… again
After running 8 back to back batches at 775g including a few very chaffy naturals I noticed right at cooling on my last batch some smoke escaping from the back of the bullet and the lid of the bucket. I opened the chaff collector of the Bullet and the thing was COMPLETELY FULL and the squirrel cage fan was clogged up as well.
Airflow during the roast through the system seems fine. No other indicators of reduced flow rate based on chaff, smoke, or even roast profile. The inline fan is operational at full speed. What am I missing? What would cause the backup in the bullet? Not enough CFM during cooling? I have no reductions or restrictions in the system anymore now that everything is 4" all the way through. Hmmmmmmmm
UPDATE: After roasting the chaffy Bali Kintamani back to back again yesterday I was still getting chaff collecting in the Bullet collector and burps of smoke and chaff when switching into cooling mode. I ordered another inline fan to see if boosting the airflow would resolve the issue – answer IT DID! Thankful to have the indoor venting solution finally solved.
It did create another issue in the bucket. The 4" cyclone is allowing so much airflow that the chaff is being sucked out of the bucket and shot into the yard again. I need to figure out a baffle or some other configuration to try and mitigate that. If I can figure that out then my setup is finally complete after so many tries.
I wonder about the placement of the little 4 inch elbows in the lid of the bucket. I know there is a “balance” point where the centrifugal force will drop the chaff and keep it from escaping the bucket. It would be easy enough to make a cardboard lid that just sits on your bucket and try different placements of the elbows. I think that the first one that I would try is to put one elbow as close to the inside diameter wall of the bucket and then have a straight pipe coming out of the center of the lid for the exhaust. Or maybe put an extension on the inlet elbow going into the bucket and then a baffle and a straight line exhaust. The 2.5 inch Dustopper has a baffle in it that must help keep the chaff and dust in the bucket.
Another idea that would be cheap to try would be to take another bucket and cut the end off and then stack the two bucket so that you would end up with a tall 10 gallon bucket. Again giving the chaff time to drop to the bottom.
With my setup and 2.5 entry and exit hoses, I am not getting any chaff that exits the bucket, and I have shortened my 5 gallon bucket. (so that it would fit under the top shelf of my cart.)
There’s very little clearance inside with these two elbows. They both basically sit right up against the wall of the bucket. The instructions want them to have elbows facing opposite directions inside and vertical outlets outside. I had the same thoughts that the height of the bucket and the diameter of the adapters really circulate the air and pick up chaff in the process. I may try swapping the orientation of the outlet so that the elbow is on the outside and I will connect that to the venting to see if that makes a difference at all. The attached picture is in a larger bucket but I wanted to give you what the setup looks like. In a 5gal bucket the elbows are back to back and basically touch
I’ll try to avoid stacking buckets if I can! I’m interested in also trying out adding a baffle but I couldn’t find anything online to help with design or orientation. Last thing I want is to reduce airflow again.
So I ended up doubling up on the buckets like you suggested @billc and that has solved my chaff escape issue entirely which is AWESOME!
Roasting about 8 batches back to back this morning and on load #5 I noticed some smoke escaping from my system toward the end of the roast. Not a ton but enough that I could notice it and thought that was a bit strange as airflow seemed to have been resolved when I added the second inline fan into the system after the chaff cyclone bucket.
Checked the Bullet’s chaff collector and it was full! How do I know if this is just something I need to check every 3-4 roasts and empty or if the actual exhaust fan/motor on my Bullet is dying or not running as it’s supposed to? I cleaned the squirrel cage fan recently and calibrated the fan settings with no issue or error but something seems to be off… or am I the one who’s off?
Edit: After re-reading the above thread, I realized that you had already answered a question that I just asked.
So I removed that question.
Do you have the baffle that I shared the STL for installed in the Chaff collector? That keeps the chaff collector assembly from collecting chaff in the bottom of the Collector.
Yes, it’s been installed for quite a while now… here is a picture of where the chaff is collecting. It’s not an entire roasts worth but significant enough that it has me wondering what’s going on. It collects above the baffle and isn’t cleared out by the Bullet fan or the inline fans. Not sure if there’s some kind of backdraft keeping them inside the Bullet chaff collector assembly or what?
) and see if you still get the “burp”
