Air flow Question on Ambex

[PerfectDayCoffee]

Sorry this is a re-post because I Kinda Hijacked another thread with it the other night

when i first started using my ambex it was suggested that the manual cooling damper always be set wide open because of bad venting on the ambex which could otherwise get smokey coffee. But I don't think that's true in my situation with my nice short 2 separate pipe venting- I took a match to the trier hole to check the draw on the machine and it seems good even with the damper almost all the way closed.
When warming up it is very difficult to get my ambient/air/drum temperature above 400*F with the watlo turning on and off at 450*F. My turn around time is always at 1 minute between 148*F to 160*F depending on the season (room/bean temperature). I think it should probably be higher.
Also, even when i keep my gas constant, I loose a couple of degrees a minute on my ramp-meaning at 5 minutes my bean temp is 20* warmer at 6 minutes its 18* warmer at 7minutes 16*warmer- So I am loosing energy-
Question Will closing the vent up get my turnaround temp Higher? Will it keep my ramp steadier and do I want that.
When is it best to keep it more closed and when do you open it? and do you do it in stages. Instinct says close as much as it can at start open -a little open at 300*F and wide when you want to adjust for First Crack

I've been playing with it just lately ( kinda dont know what to look for) I understand wanting to roast with mostly convection but don't see the value of closing up the damper as far as taste goes.
To ad to my confusion I played with the damper before adding beans and surprisingly it raised the ambient/Drum Temp but caused the temp on the watlow to get lower even though it had just been rising steady with the gas at like 5 water inches on my gas gauge. Whats that about?

- I love my coffee But Better is always best and I always wonder about how /why /when to play with the damper.- feed back would be appreciated thanks

• :coffeemug:
  

 

[PerfectDayCoffee]

hey roasters any thoughts you would like to share?

 

[eldub]

We roast on USRC equipment and I have no experience with Ambex roasters.

That said, I know many roasters use air flow to control their roasts but I mostly use the gas to control temps and air flow to impart a smokey flavor at the end of some dark roasts.

After charging the barrel you must keep the ambient temp rising if you wish to maintain a constant or increasing rise in the temp of the bean mass. During the first roast of the day, I often run the gas wide open after charging the barrel, through turn around and even until the bean mass reaches 300*. If by then the ambient temp of the roaster is around 400* I will gradually decrease the gas in order to maintain that ambient temp while factoring in the rate of rise in the bean temps.

As more batches have been roasted and the equipment heats up, I often work in reverse, starting off with very little gas and increasing the heat applied as the roast progresses until optimal levels are reached. Then I start backing off the gas in order to slow the process as first crack is reached.

Not sure this will help. Sounds like your roaster is maybes losing heat somehow?

lw

 

[peterjschmidt]

That does sound odd that you'd be going down in temps, rather than up.

Last month I did two batches of Guatemala in my Ambex YM2K, with the intention of answering the airflow question for myself, and what effects it has in flavor. I've been roasting this particular bean for months, and know it well. The first batch was with airflow completely closed (the damper set to pull air mainly from the cooling tray) and the second batch was with full airflow (air mainly pulling from the drum). I used the same time and temps as my normal profile, so I had to use the gas valve to hit those settings, since having the air closed would cause things to move more quickly.

The results were not all that different, but the 'closed' roast had a deeper flavor w/ more bass notes, while the 'open' roast had more nuance, and higher fruit notes. But again, it wasn't a day and night difference, and both were good.

PDC, I'm wondering if your Watlow probe is acting up. IOW, if you have it set to cut the gas at 450, you never reach that and it would run w/ the flames full-on all day? What do your flames look like? Are they orange/yellow indicating dirty nozzles? Are you using NG or propane? Mine is propane, and at high flame the pressure is just under 10bar. What sort of pressure readings do you have? You may also have a bad regulator.

When I dump a batch of beans, I have the damper set to cooling, or closed. Once I drop the next batch (make sure the valve on the drop hopper is closed) I set the damper to full, to draw out any moisture coming from the beans during the drying phase. At 280* I figure the drying is done (as indicated by beans in the trier turning from green to yellow) and flip the damper to closed, to hold in more heat and start the climb toward 1C. All that time, the gas is on full. Depending on the overall objective and where the roast will end, I will reduce the gas to either 6bar or 4bar, anywhere from 325* to 350* (in order to not be too aggressive going into 1C), and generally will have the damper at 1/2. Generally, for a City+ to FC roast, I will further reduce gas pressure 1 or 2 bars in the middle of 1C, which begins on my roaster in the mid-370's, and the bean mass will have enough momentum to finish 1C and continue climbing gradually, until I dump. 406-410* for City+, ~420* for FC, ~435* for a rolling 2C.

Hope some of that helps.

 

[eldub]

Peter: can you get beans to taste like coffee (not under roasted) at 410*? My results are usually grassy in the extreme at that roast level.

 

[peterjschmidt]

Peter: can you get beans to taste like coffee (not under roasted) at 410*? My results are usually grassy in the extreme at that roast level.

It's probably that our temp probes are bent differently.

My 1C temps are mid-370's, finishing mid-390's, so 410 is well past 1C. Where are you going through 1C, and how far past that would 410* be on your roaster?

 

[eldub]

My first crack temps usually start about 486*. At 410* I'm usually still in first crack.

I understand now.

 

[JumpinJakJava]

Eldub  "My first crack temps usually start about 486*", I believe you mean 386*. I am in that ballpark. 380-384*, would be my average for 1st crack.

 

[PerfectDayCoffee]

Thanks all _ No I dont Think there is anything wrong with the equipment. It's just that I never played with the exhaust because I heard Ambex wasn't designed with that much draw and that closing the damper any amount would get your coffee too smokey. But looking at my ramp and how others have higher turn around temps and checking out the machine I wonder if I am missing out on a variable that could work in my favor( make even better coffee)- I understand wanting air- for moisture and even heat - -and getting rid of smoke and chaff. What I dont get is why and when you would shut the damper. Its not like I need the energy I start at 5" and I decrease it to go from ramps of 30*F per minute to 20 and then 10*F per minute between cracks. My coffee is nice and bright -Fruity when its in the bean.

 

[LBBeans]

Have you checked with Ambex? I'm curious to know what they say. I normally have the damper wide open but have been playing with closing it recently.