Airflow is way too strong, advice on how to lessen - Probat P12

Ryguy

New member
Nov 15, 2018
4
0
Hello!

I roast on a Probat P12 (built 2019). This roaster does not have the VFD airflow control, as my intention was to leave airflow set at a constant throughout my entire roast.

I have a very glaring issue with this roaster however, the strength of the airflow fan is CRAZY. Roasting with the damper closed as far as possible the flow is strong enough to extinguish a lighter at the trier. This makes proper development incredibly hard.

I'm wondering is there may be any tricks to dampening this airflow aside from the damper itself. I had considered extending my chimney a few feet, or adding an addition bend in the ventilation but I figured I would look for some outside advice before I have my chimney reaching 10' high off my building.
 

Musicphan

Active member
May 11, 2014
1,537
12
Kansas City
Was variable airflow an option???? Per their website the P series has "Variable airflow and variable drum speed options for better profile accuracy on smaller and larger batches."
 
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Ryguy

New member
Nov 15, 2018
4
0
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It was, and I opted not to get it because I thought I would be setting the damper and leaving the airflow at a constant.
 
>>Roasting with the damper closed as far as possible the flow is strong enough to extinguish a lighter at the trier.
The damper is (typically) located in the exhaust stack after the drum.
When you remove the trier, the state of the damper wouldn't matter with respect to the air flow coming out of the trier hole - you would get the full blast of the fan, limited by the diameter of the trier hole.
Only when the trier is in place is the damper properly limiting the airflow through the drum.
You should see what airflow is coming out of the exhaust stack (with trier in place) to decide whether the airflow is too much for your requirements.
 

wmark

New member
Nov 12, 2008
475
1
Canada
All right. I have the same roaster only with the VFM. I installed it after the fact.
1st thing to do is to invest a couple hundred dollars in a manometer and measure the air flow pressue differential in the back. It is suppose to be set at -2.0 millibars.

You should ask Probat to direct you. Failing that, I could give you a hand
 

Balloonsy

New member
Apr 24, 2020
1
0
I have this exact same issue. It's rather infuriating :(. To be honest, I think the only fix is to get VFD installed after the fact if possible. Please let me know if you find any other tips/tricks to fix this issue. I really think it limits the potential of the coffee.
 

Musicphan

Active member
May 11, 2014
1,537
12
Kansas City
wmark - how did you add after install? Sounds like people could use the info. I'm shocked VFD is not standard... seems to be a basic technology of modern roasting.
 

Nugget

Member
Dec 7, 2014
53
0
You’re basing the idea that you have too much airflow on the Rao lighter test?
I haven’t found that tip to hold true with my roasts.
Are the roasts dragging out? Or blowing out your burners or sucking beans out of the drum? Or are you just going by the lighter thing?
 

Nugget

Member
Dec 7, 2014
53
0
Btw just trying to understand. If the airflow is messing with heat transfer and making roasts lag and baked, it’s not good.
 

wmark

New member
Nov 12, 2008
475
1
Canada
probat can retrofit a VFM on the Probatone.
That said, I think I am still having air flow issues as no one can seem to tell me what constitutes low, medium and high air flow.
The VFM can only be reduced to 50% ............I need/want to get airflow lower at the beginning
 
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