As the demand for freshly roasted coffee at my church grows, I decided to move our R2 Pro out of the garage and to its own permanent home with an all-new 220v electrical connection and the ventilation components mounted on the wall. Here is a photo of the new setup:
On the outside, there is a sealed vent hood with a gravity damper. I had everything installed by a professional to ensure compliance with safety codes.
Unfortunately, however, I just finished my first roast and our Temptop air quality monitor went berserk and reported the air quality as HAZARDOUS. It went from GOOD to MODERATE to HAZARDOUS in a matter of seconds somewhere between dry end and first crack. Thank God, I had an N95 mask nearby and immediately put it on, but the whole thing shattered my hope that I could safely roast indoors with a proper ventilation setup pushing the harmful fumes outside. Here are the parameters of my roast:
For what it’s worth, the 6" AC Infinity fan was at its max setting during this roast of 1.1 kg of Brazil beans.
Here’s what I did to troubleshoot:
I checked all the connections to ensure no air leaks and went outside to feel the strong stream of air from the vent hood. There is also discoloration on my stucco from the coffee matter that was pushed out with the smoke. The ventilation is definitely working,
I put my hand over the exhaust port of the R2 Pro to ensure the fan was spinning and responding to different fan speed changes. There was a steady stream of hot air and it seems that the fan is working properly.
I ensured the chaff box and mesh cup were completely empty and clean before this roast.
There was no sound of the fan rubbing against anything when I turned on the machine and listened before pre-heating.
Apart from that, I don’t know what else to check. The only hypothesis that comes to mind is that air is leaking from the roaster at a point other than the exhaust port into the ambient air.
Does anyone have any experience with this or ideas as to how we can mitigate this issue? We just want to roast indoors without having to worry about noxious fumes and wearing masks while the ventilation does its job.
I will tell you what I think it is. The fan is simply too far away and has obstacles, such as the filter box, to suck in all the smoke. I understand that people might think that it should go that way, but if you put the fan first, which is what I do, there shouldn’t be any problems. Of course, you’ll have to clean the fan after every roasting session. You could get some much more powerful fan, if there is one, but it would fly off the wall at the strength needed to pull all the smoke through everything and expel it. And I also think that the filter box should be as far away as possible, or to put it simply at the end and the nearest possible to the exit. This way it’s just choking the airflow. You should concentrate on the main task here, which is to get smoke out. If it remains in, no amount of filtering will help, save for the electrostatic precipitator, which on the other hand releases ozone, so it’s a lose/lose type of situation.
I appreciate your response and point of view. To see whether fan placement is an issue, we ordered a second AC Infinity S6 fan that we will place between the roaster and the Y-connector. This fan will have no other purpose than to suck the air from the R2 Pro’s exhaust port. I’ll keep the second S6 at the end of the line after the filter. Based on my research, this is a “series fan” setup that should provide better performance throughout the whole system. I’ll report back with results.
In the meantime, I want to mention that I thought the filter box might be the issue, as well, especially since I have a MERV 11 filter in it, so I tried another roast without the filter to see if it would help. It did not. The air quality still reached UNHEALTHY on the monitor.
Well, the only thing I know is that if you’re reaching those unsafe levels, the smoke is not exiting the room fast enough. I will see the air quality deteriorate, if I’m doing more than 3-4 roasts, but that’s only for 30 seconds or something like that. If you have a thermal camera or something like that, it might give you an idea where the smoke is escaping the system. My guess is right at the beginning, but I might be wrong and there’s an entirely different fault. As you have hired, and I’m guessing paid, a professional to ensure compliance with safety codes, you should call him and tell him that compliance was not ensured. I wish you the best of luck in solving this.
Hi there. Try closing off the duct that pulls air from the cooling tray. You only need suction from the cooling tray when the beans are dumped (maybe not at all, as it is just heat radiating from the beans as the beans cool, I doubt there is any particulate to be concerned about from the cooling tray). I have a similar set up with a S4 fan, and do not run a duct to the cooling tray at all. The S4 is just adequate when only pulling from above the exhaust of the roaster.
Another take on this that needs to be tested/checked is that exhausted air may be mixing with the air in the roasting room. That can happen if the exhaust port is near the air source for the room or if there is no unrestricted fresh/replacement air supply. In the latter case the effect is that air flow thru the fan is less than spec’ed. Adding more fans doesn’t change anything- you need unrestricted access to fresh make-up air.
In order for the smoke to be properly exhausted, there must be a way to draw fresh air into the roasting room. Is there a way for air to get into the room to balance the exhaust air?
Thank you all for your input. Yes, I have both a window behind me and a door that lets plenty of air into the room right next to the roaster. In my roasts yesterday, I kept the window open and the door closed, but I can try keeping both open as a test.
Today, I will put a blast gate on the 4” ducting to keep it closed except when cooling the beans. I will also replace the high efficiency MERV 11 filter with a less restrictive MERV 8 filter. If all else fails, I’ll put the second fan in series right above the roaster.
As an update, I installed the MERV 8 filter in place of the more restrictive MERV 13 filter. I also installed a blast gate on the 4" line to the cooling tray and kept it closed during the roast. Finally, I also kept the door next to the roaster open the entire time.
Unfortunately, the air quality still reached UNHEALTHY for most of the roast followed by VERY UNHEALTHY as I approached the end of the roast. It was not a dark roast; the Agtron is 63.9. I do think the MERV 8 filter allowed for better airflow as the air quality monitor did not go berserk, but even with all the changes, I couldn’t keep the air quality at a reasonable level as I could when the setup was in the garage.
Now, I have to decide whether to mount the additional AC Infinity fan in series right before the hood above the roaster. I’m hesitant, because I feel good airflow above the hood and don’t know how necessary it is, but at this point, I’m not sure if there is any other option.
As a further update, I added the second AC Infinity S6 Pro in series right above the hood that pulls air from the R2 Pro’s exhaust port. It did not go well.
@ibnabouna
I would be very careful about trusting an N95 mask to protect you. To the best of my knowledge N95 masks only filter out particulate matter and can’t filter out airborne chemicals, gasses, fumes and vapors.
Please be careful and investigate that the N95 is sufficient for your protection.
One of the things that I did in an earlier iteration of my Bullet setup evolution, was to create the equivalent of a mini paint spray booth with easy open doors. So, basically a full enclosure with and exhaust fan. The fresh air was being drawn from the room air and exhausting to the outside.
I had built most of it out of cardboard to test the theory. For my purposes at the time, it did okay.
I don’t know how much bad stuff will get into the air when you open the door to drop the beans…
Hi Abouna, I think the fan speed you are using during the roast is way too low for the batch size you are roasting.
There is a good chance that more roasting gases are created during the roast for that batch size than a fan speed of F2 and F3 can effectively exhaust during the roast causing excess roast gases to escape from the machine in other ways and into the room.
I roast 300g batches and go up to as high as F5 just before first crack on most roasts.
I think your fan speeds may be way too low for the batch sizes you are roasting. Something to explore perhaps. Hope it helps Abouna
In that process, I discovered a hole in the flex hose that connected to the inlet of the filter box and replaced it with a good section of hose. My hope was that the hole was causing all of the issues, so I tried another roast wearing my P100 respirator. Thank God I wore it, because the air quality was back to HAZARDOUS with all the numbers maxed out at 9999999.
After cooling down the roaster and doing other things, I returned to inspect all of the hoses and connections to make sure there were no other holes. I found a couple of minor air leaks using the candle test and patched them with new hose/duct tape before trying another roast. This one seemed promising with air quality being at GOOD and the numbers very low during pre-heat and the first part of the roast, but after dry end, the numbers started to increase rapidly until I once again reached HAZARDOUS right around FC. The numbers were not maxed out at 999999, but they were high.
Unless my entire wall is permeable and bringing the toxic fumes back inside, I can’t make sense of this. Again, I wonder if the ventilation is working fine with respect to the exhaust port of the roaster, but there is another leak somewhere else on the roaster.
Abouna, if the air quality reading is getting worse just before first crack that makes sense because that probably when a sudden rush of gas is being released from the cracking beans.
Strongly suggest trying higher fan speeds just before you reach first crack and then raise it again during/after first crack to more effectively expel the higher volume of roasting gases created at that stage of the roast.
That could very well be a contributing factor. This is the same recipe I ran when I was in the garage with no issue, but maybe a higher fan speed will help in the new setup. I can certainly try.
I wish it was better news, but even after adjusting the recipe for higher fan speeds, I had the same issue with air quality going to HAZARDOUS.
The plus is that I have a lot of freshly roasted coffee to share after all these tests.
I think I will retire the R2 Pro for now until we find a solution. I’m not sure how people are using these underneath kitchen vent hoods or even outdoors. An air quality monitor is probably a good idea for safety if you’re using a Bullet in any context.
