FredK Senior Member Joined: 28 Jun 2009 Posts: 140 Location: NJ Expertise: I love coffee
Espresso: Gaggia Classic Grinder: Kyocera hand grinder Roaster: FreshRoast+8
Posted Tue Aug 25, 2009, 9:33pm Subject: Freshroast Plus Dimmer switch
Is it neccessary to use a 1000 watt dimmer switch on the Freshroast roaster or can I get away with a much less expensive 600 watt dimmer? Just looking online, it seems the 1000W are about $40 while the 600W are about $5. Thanks.
JKalpin Senior Member Joined: 28 Dec 2008 Posts: 242 Location: Thornhill, Ontario Canada Expertise: I love coffee
Espresso: Aerobie Aeropress Grinder: Baratza Maestro Plus Vac Pot: Yama 5-Cup Drip: Bunn Roaster: Freshroast Plus 8
Posted Wed Aug 26, 2009, 4:11am Subject: Re: Freshroast Plus Dimmer switch
FredK Said:
Is it neccessary to use a 1000 watt dimmer switch on the Freshroast roaster or can I get away with a much less expensive 600 watt dimmer? Just looking online, it seems the 1000W are about $40 while the 600W are about $5. Thanks.
I have considered that too. Two things bother me about it:
My FreshRoast +8 draws 9.8 amps, just a bit under 1200 watts, more than your 1000w dimmer. It draws that very consistently (except when cooling).
If you use (say) a Variac to 'increase' the voltage, then the fan goes a bit faster and that's OK. If you use it to 'decrease' the voltage then the fan runs slower and the mixing is less and the roast could come out uneven.
I see some people used 1000W and others used 600W dimmers. Just want to make sure I don't burn down the house.
I just got the Freshroast+8 as a present, looking forward to playing around with it. Seems that the heat has to be toned down to extend the roasts upwards towards 11+ minutes for espresso, which is really the only thing I will be using it for.
The other trick to extend the roast is to shut it offf for 30 seconds or so at a time during 1st and 2nd crack.
JKalpin Senior Member Joined: 28 Dec 2008 Posts: 242 Location: Thornhill, Ontario Canada Expertise: I love coffee
Espresso: Aerobie Aeropress Grinder: Baratza Maestro Plus Vac Pot: Yama 5-Cup Drip: Bunn Roaster: Freshroast Plus 8
Posted Wed Aug 26, 2009, 9:29am Subject: Re: Freshroast Plus Dimmer switch
Fred, I have been using my FreshRoast + 8 for almost a year now, more than 160 roasts. A practical problem is that the roast happens quickly, in total around 5 minutes, and it's hard to know 'exactly' when to terminate (go to cooling). The last 20 or 30 seconds can make a big difference.
My solution was a stainless-steel sheathed type K thermocouple and thermocouple reader. See the pic below. The thermocouple is available for around $10.00, click here. The 10 cm probe length places the tip in the middle of the bean mass. Just drill a 5/16" hole in the middle of the chaff bonnet (comes with a mating nut). The instrument is around $30 click here. So the whole outfit, including shipping & handling was around $40.
Once I determine where I want to terminate my roast I note the bean temperature. Then I can do roast after roast and end up at the same spot. For example, I am terminating Costa Rica 'La Margarita Honey' at 460F. I don't even listen for the cracks.
Would I spend more money on the system, to add a Variac, split out the fan circuit etc? Actually, no. It's too much money and too much bother. When my FreshRoast + 8 dies I will go to a Behmor.
I ran my first batches today on the Freshroast, and they look great! And it turns out I didn't need a dimmer because I measured my line voltage and it was only about 116V. So on my first batch, I didn't get to second crack until 9 minutes. And this was on a stock, unmodified FR8. Very nice.
I stuck a thermo thru the screen into the chamber and monitored the temp during the process, here is how it went. I used SM's liquid amber beans, 60.0 grams per batch.
minutes/temp F
0/72 1/275 2/340 3/363 4/372 started hearing 1st cracks (popcorn sound) 5/383 6/395 7/403 cracks stopped completely 8/413 9/417 second crack starts (rice crispies sound) 10/422 11:30/425 turned to cool 12/389 13/287 14/185 dumped in collander
I ran a second batch after waiting 20 minutes for everything to cool. This batch hit second crack at 8 minutes, a minute sooner. Not sure at what point I should stop it once it goes into rice crispie mode.
Interesting that after the second batch I measured the voltage on that socket again and it was up to 119V. I had no idea line voltage varies so much. I could drop it 1V by turning on the microwave or kitchen lights. I imagine the voltage might have been slightly higher during the second batch because the measured temps where slightly higher, about 10 degrees at each time point.
Posted Wed Aug 26, 2009, 5:56pm Subject: Re: Freshroast Plus Dimmer switch
This is not as bad an idea as it may seem at the first look. Incandescant lamps are very difficult loads. A cold incandescent lamp has about 1/10 the resistance it has at it normal operating temperature. Phase control dimmers have to be designed to handle that. A 1000 Watt heater may not be much more of a load than 600 Watts of incandescent lighting at 1/2 Voltage. At full Voltage of coarse they will be similar.
You aren't risking much as normal 600 Watt dimmers are cheap. You might be somewhat conservative by either blowing air across the dimmer or attaching it to a large metal heat sink.
Phil
FredK Said:
Is it neccessary to use a 1000 watt dimmer switch on the Freshroast roaster or can I get away with a much less expensive 600 watt dimmer? Just looking online, it seems the 1000W are about $40 while the 600W are about $5. Thanks.
Posted Wed Aug 26, 2009, 7:41pm Subject: Re: Freshroast Plus Dimmer switch
JKalpin Said:
............... A practical problem is that the roast happens quickly, in total around 5 minutes, and it's hard to know 'exactly' when to terminate (go to cooling). The last 20 or 30 seconds can make a big difference. ..............
A 5 minute roast is lightning fast, and slowing it down is the reason to use a dimmer, router controller or variac. (these other options are a good bit cheaper than a variac, I use a variac because I already had 2 in my electrical tools.)
It's more than just terminating at the right point, it is also how long the beans spend at various stages of the roast to develop the flavors.
Plugging the whole unit into a voltage limiting device will slow both the fan and the power to the heater. This is working against getting a good response from the controls. Lower air flows not only limits bean movement but also leads to higher temps as the volume of air over the heater is less. (exactly what you don't want!)
By separating the fan and leaving it on full power, and only adjusting the heater coil output, you have a much more responsive control knob to profile the roast.
Running a poppery I this way, I have tried many different profiles, (and burned through many batches working on profiles that finished in under 8 minutes.) I will say that I have never had a roast finish in 8 minutes or less that was better than a 9 or 10 minute roast. I have tried many ways to 'beat the clock' on this; extra hot drying phase, super fast ramp to first, speedy hot finish. (.....My shortest, brightest light roast is now around 9 minutes, 6 minutes to first crack.)
If your roaster provided the knob to adjust the roast time you may find a whole new dimension of flavors in the beans you are roasting. The harbor freight router controller is about $20.
FredK Senior Member Joined: 28 Jun 2009 Posts: 140 Location: NJ Expertise: I love coffee
Espresso: Gaggia Classic Grinder: Kyocera hand grinder Roaster: FreshRoast+8
Posted Wed Aug 26, 2009, 8:11pm Subject: Re: Freshroast Plus Dimmer switch
How do those temperatures look above? If using a variac/dimmer, are you trying to keep a certain constant temperature? What would that temp be or what range of temps is optimal, on avg for avg beans? Just trying to get a ballpark on where temps should be. I measured these temps with a k type thermocouple hanging in the chamber, about 1" from the top, not touching anything.
Posted Wed Aug 26, 2009, 8:37pm Subject: Re: Freshroast Plus Dimmer switch
FredK Said:
How do those temperatures look above? If using a variac/dimmer, are you trying to keep a certain constant temperature? What would that temp be or what range of temps is optimal, on avg for avg beans? Just trying to get a ballpark on where temps should be. I measured these temps with a k type thermocouple hanging in the chamber, about 1" from the top, not touching anything.
I'm guessing you are measuring the air temp after it has passed though the bean mass? This is fine as long as you are consistent in probe placement for your reference. I would suggest to slow down the first part 'drying phase' to be at 300F around 3 minutes. Then take the temps (power to the heater) up a bit to reach first crack in another 4 minutes or so. You may notice the thermometer reads a bit higher for first crack this way as there will be less temperature gradient across the roaster going slower. Once first crack gets underway, you may back off just a bit on the heater power enough to slow the temp ramp but not to let it stall or drop. Try to finish the roast 3-4 minutes after start of first crack and at your desired degree of roast..(tricky!) Don't worry or panic if you miss these marks, better to be steady on the throttle then to jump up and down with the heat/power trying to hit a temp/time gate.
Congratulations on your first roasts!!! Not a bad start!
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