I don’t know what kind of filter you have available to you in Spain. Further up this thread you should see pictures of the types of filters some of us have used. I use a filter that is typically used for residential HVAC/furnace systems in the US that looks something like this. I am able to fit it in between the baffle filter and the actual fan motor of my exhaust hood and it works well for me. You’ll just have to figure out what works for you and your exhaust hood. Good luck!
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Newb here. I just got my bullet in and am in the process of setting up my ventilation. I’ve seen a lot of great posts (thank you all) showing in-line fans and I have come up with a few questions, if anyone has a minute.
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If I have the 3d printed adapter and am set up right under a window, is the passive set up going to work ok? I’ve seen some comments that suggest that maybe it isn’t. I would have a separate exhaust for the tray going out the bottom of the window through an ac window vent and the roaster exhaust going up a few feet out the top of the window.
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If I stick with the 3d printed adapter, but decide to use a fan what is the best cfm for connecting directly to the adapter? I don’t want to affect the roast air flow, of course.
3)If I ultimately decide to place a fan in and have a hood suspended a few inches above the roaster, what then would be the best cfm. I’ve seen people say that the s4 should be sufficient, but others saying the s6.
Again, newb here, so any advice would be greatly appreciated. Thanks!
I don’t use this setup as I put my bullet under a range hood that has 6 steps to reach 900 CFM. That said, much probably depends how dark you plan to roast. If you roast dark you might want the option of being able to have higher CFM. I have accidentally triggered my smoke detector once when I didn’t crank up my range hood enough when I was doing a really dark seasoning roast in the beginning. My typically roasting is to drop between 420 and 435F (in 1kg batches) and my hood setting is around a 5. There will be more “smoke” when you roast dark. So if you think you’ll regularly roast up to and into 2C go for the S6.
Thanks for your response! I will be roasting mostly light and medium roasts so I may just see how a passive setup works and adjust accordingly. Maybe I’ll do my seasoning roasts outside to avoid the heavy smoke indoors.
That’s brilliant! Nice work.
Haha, Thanks!
Hope it inspires some solutions to people’s venting problems!
P.S. it’s been working so well I still use it as is 
Love your invention Bill. Thanks for sharing
Soooooo,… is venting really necessary? I just got the bullet 2 not that long ago and the “smoke” doesn’t seem bad at all? Is it just after lots and lots of roasts that buildup causes “smoke” damage?
Please don’t roast me for this question. 
(Pun intended)
Necessity is in the nose of the smeller I would say.
If you are fine with it, people around you are fine with it then just keep on keeping on until you are no longer fine with it!
P.S.
I chose to vent cause it just seemed like the thing to do at the time. When I started dabbling in darker roasts I was very happy that I did!
Hope it helps, cheers!
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If you are roasting indoors venting is absolutely necessary. I roast indoors and I’ve had my smoke detector go off because I didn’t turn up my vent hood high enough when I was roasting dark for the seasoning of the drum. Also for your indoor AQ you should be venting out.
If you’re always roasting outdoor you’re all set 
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Thanks!
I’m used to campfires and wood stoves and all that jazz so I guess I’m less sensitive,… but good advice in the “see what happens” bit.
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How do did you get your ventilation tube to stay in that position?
YES. Smoke from roasting is bad for your lungs. If you research it there is actually a name for the condition is causes. Your lungs are not designed to breath in smoke. long term it could be an issue, short term infrequent…prob not but who wants to roast infrequently/
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Love your set-up! Sorry to revive an old post, but I have the same situation in my basement (indoor grill, apparently also popular in the US in the 70s!) and am looking to convert it to be able to roast indoors. How is your exhaust working for you at this point? I tried a 900 cfm bathroom/kitchen exhaust and it didn’t clear enough smoke (while the fan is powerful it seemed to churn the air more in that built-in BBQ area) so I’m thinking of going to an in-line type fan instead
Looks great! How has this set-up been working for you? Does the splitter running to the cooling tray make it so that the S4 doesn’t pull as strongly from each side? Was wondering if I’d need 2 separate fans: one to each of the cooling tray and exhaust, or if one S4 with a splitter like you have would work
Hey Tablemountain,
Yes - venting a roaster is the highest and best use for an indoor BBQ grill!
My venting arrangement has worked flawlessly, save for the couple of times I forgot to turn the fan on. (I’ver since set it up so that when I power up the roaster, the fan comes on automatically.)
Even during the seasoning roasts, I’ve been barely able to smell any smoke, much less have to deal with it.
Here is a pic looking straight up the flue.
I completely blocked the flue with a piece of 3/4" plywood and installed a 10" muffin fan through it. The widget on the left is the existing flue damper operator (in the closed position). The wooden toggle blocks the slot when the damper is open to prevent pushing any smoke back down (probably an unnecessary nicety).
Since I didn’t really know how much trouble getting rid of the smoke was going to be, I sized the fan to be largest, highest capacity I could fit. It is definitely overkill. I have it connected to a Variac and it is dialed down to about 1/2 sped, and I could definitely go lower.
I stretch a pink, support breast cancer research, women’s silicone swim cap over the fan when not in use. This keeps convection drafts from motoring the fan, which is annoying sounding and not good for the bearings.
I purchased the fan used on e-bay, and replaced the bearings.
Good luck and feel free to reach out if you have further questions!
-Gray
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Thanks for the informative response!
Interestingly, my indoor BBQ has a 6" duct at the top rather than a traditional flue (a few photos attached). I started with a new 10" 800 CFM exhaust fan, but I found that it just churned the air below the fan (check out this 6 second video for an illustration). I am 98% positive there is not a blockage in the duct, but perhaps the 10" fan was too big?
Nonetheless I’ve been considering going to an inline duct fan to connect with that 6" exhaust duct instead. Upside is that it might be more efficient, downside is that it might not capture all the smoke as other exhaust methods such as yours, and there is also not a lot of room to work with a Cloudline S6 type fan in there.
I have seen how the smoke build up affects glass, so I can only imagine the nice yellowing it does to lungs. 
If you do one 350g or smaller batch, then nothing more than a cracked window is probably good enough.
The other thing, is that smoke residue can cause a type of nose blindness. Not sure how many of you come from a working background like me, but I have done metal work and couldn’t smell or taste anything beyond sweet and salt for 48hrs. So if you go from roasting in smoke to cupping, it can throw off your perception. Which may not matter unless you are a solo roaster.
No need to mess around and find out. I think we care about your health and career enough to share experiences. But obviously it is your choice, and you may have additional reasons, such as traveling with the bullet and only minimal roasting needs. So can’t really give you hard rules. But in general…
Ventilation is a good thing, if you can accommodate it.
Hey Tablemountain -
Wow - I’m really surprised that that ever worked as a grill - wouldn’t think you could create a strong enough draft from convection alone.
I think the problem with your first try is that the static pressure is too high for the fan used. And, I never trust those fart fans to do much anyway - most are engineered with no economy spared. Certainly the CFM rating assumes an almost zero static pressure.
I would think that a duct fan would be designed for a higher static pressure, but I don’t have any direct experience. Squirrel cage type blowers are usually capable of moving more air in high static pressure situations, so that might be another route to go.
Let us know how your experiments go!
-Gray
PS - I like your lights - think I’ll steal the idea from you!
Not sure who could use a setup like this, but it is pretty clever nonetheless