How to properly preheat Huky before a roast?

[PabloElFlamenco]

Yesterday, during my first Artisan-recorded roast, I took pains to properly pre-heat Huky which, from information weaned here-and-there, was recommended to be "20 minutes" or so.
During the process, Huky "empty" (of beans) of course, I had Artisan hooked-up and soon had the ET, BT, MET(?) up well beyond 300°Celsius (over 600 F), which made "20 minutes" make me fear en empty Huky could possibly "overheat".  Trying to reach "20 minutes", I decreased the blue knob from 4 kPa down to 2, and after that even less, until I in fact, after more than 15 minutes, shut off the heat altogether, expecting to have Huky then lower temperature until reaching the "230C/446F" point, when I would load the beans.  I took the opportunity of "testing" to see what the effect of 100% fan would be and, behold, the temperature dropped fast (and so, lit the stove again).  Anyway, at 230C I loaded the beans and started the roast.

Just to have a reference, at what stovepower do you preheat Huky, what are typical temperatures reached in doing so, and how to you reduce that temperature to the proper one for loading beans (which is?).  Trying to put my finger on the pulse...thank you!

[edtbjon]

As I brought it up in the previous thread...
I usually set my stove at 1.5 - 2.0 kPa and just that whiff of air so that there's some circulation. Start Artisan and just press "ON" (to get the LCD windows active showing the temps...). After that I usually weigh up my first batch, position everything, brew a cup etc...
What I'm going for is to get the roaster up to temps around drop temp and letting it sit at around that temp range for a bit, so that the whole system is at working temp.
My idea about this is that various parts of the roaster, say even the painted part around the stove will absorb heat up to a level. Let it do that before starting to roast, so that everything is stable during the first roast, not the second. (I mentioned the stove as an "extreme", but what really does matter is the exhaust, getting the whole exhaust system up to around working temps will keep the heat in the roaster when you expect it to be there.)
The roaster usually picks up the heat quite rapidly. After some 5-10 minutes it's time to lower the gas so that the roaster coasts at around drop temp (say 220C/430F) and is steady there. (Unless you with perforated drums want to charge even higher, in which case you should choose a temp a little bit higher than your intended charge temp.) I usually go down to 0.5 kPa or so during that phase. Try to find a balance point with the variac, so that the roaster is "idling" at that temp range. In Artisan, the two (three) temp values should be close to each other, not more than 10C/20F apart. Stay in that "mode" for a while and make the last preparations for the first roast.
The last part is to cut the heat and with very low fan let the roaster coast down towards the intended charge temp. I personally charge at around 150C/300F give or take, so this will take a while, but this "waiting time" is about the same for every consecutive roast. During this phase (unless you've already done it of course ) fill in all the coffee data in Artisan etc.
All this may take some 20 minutes, it may be 15 or 30 minutes, I don't know. The time isn't that important, unless you're trying to do it too fast.
The Huky is not a production (professional) roaster. Looking at the machine, it has only the fraction of the mass of an equivialent pro roaster which makes it easier to heat, but it looses heat quicker too. Even with the T connection (and possibly a custom cyclone system) it's a bit tricky to roast back-to-back with the Huky, at least in my scenario (with charge temps at around 150C/300F). There will be pauses between the roasts, even though you can keep them down to a few minutes.
Looking at myself, I'm not a professional roaster, I do this for having fun and some relaxation. If I cannot find the time to wait for the roaster to be properly ready, I'd better go for a run or something to burn or my own personal bad energy. 
I guess most or all professional roasters does give the preheat phase enough attention and time. After all, if that first roast of half a bag of coffee is way off they've lost a grand or two to start with. 

[PabloElFlamenco]

I'm just up from downstairs where, after having put another layer of lacquer on a clothes hanger I'm making, I did a "blank" practice run the Huky, just to turn the knobs and push the buttons and trying to see the effect of this upon temperatures, etc.  Tried 4 kPa and down to very minimal kPa, to see at which point the stove extinguishes due to lack of gas, to observe the effects of "high" Variac wind, and "low" ventilation. 
For instance, with high gas, high ventilation makes the temperature rise quickly, whereas, with very low gas, the same high ventilation cools everything down. 
I find that, with a large propane tank, outfitted with a 50 mBar (37 is standard here) regulator, and a 5 meter length flexible tube (interior diameter 9 mm), the maximum stove pressure is about 4.7 kPa, and minimum very, very low (unmeasurable on the 10 kPa manometer) before the stove extinguishes.  BTW, I only employ the "large" stove burner position:  according to Mr. Li's latest instructions, I don't employ the stove's piezo-electric lighter, instead I use a separate lighter to start the ring of fire.

Mr. Li's latest instructions
Warning! Ignition Method:
1.Please turn off the blue needle valve.
2.Turn on the gas tank valve slowly.
3.Slowly open the blue needle valve,prevent the instant pressure
   over limit that causes damage on the micro pressure gauge,
4.Adjusting firepower from blue needle.
5.Turn the black ignition switch, keep it at horizontal position after ignition.

Some may have noticed that, using the stove's piezo-electric lighter makes the gauge's needle strongly shoot up all the way to the maximum and hit the stop peg, which -sooner or later- destroys it. 
I leave the black knob permanently in the "large flame ring" position, ensure the blue knob is in the "closed" position, then go out and connect and turn on the gas (outside) at the propane bottle, then put a flame-lighter onto the burner and the while slowly and lightly turning on the gas which, invariably, lights smoothly and without the slightest "whoof" effect from accumulated gas.  I am, be assured, very careful and have not observed anything untoward.

 

[SusanJoM]

I preheat for 15-20 minutes with the gas at 1.5, the drum turning, and the damper open.

What I look for is BT, ET and MET to be travelling across the page in parallel.  To me that indicates that the machine is at a stable temperature. 

It's tricky.  The HUKY has so little thermal mass that the slightest change in the ambient temperature, the temperature of the beans being loaded, the wind speed (should you be outside) etc. is enough to make specific settings unreliable.  Every roast will be different because the HUKY itself is just a variation on a tin can.

As soon as I charge, I crank the gas to 3.75 or so and let 'er rip.  Sometimes that is the only change I ever make to the 'settings'.  Usually I make some decreases in the gas somewhere after EOD.

[hankua]

300c is way too hot for a coffee roaster, and could cause unnecessary metal fatigue or stress on the components. The grease used in coffee roaster has a upper melting point as well.

There is no reason to heat it up that far except for a "mistake". Going up to your drop temperature is enough. Huky heats up much faster than other machines, and the perforated drum should be ready to use quicker than the solid.

[edtbjon]

As I brought it up in the previous thread...
I usually set my stove at 1.5 - 2.0 kPa and just that whiff of air so that there's some circulation. Start Artisan and just press "ON" (to get the LCD windows active showing the temps...). After that I usually weigh up my first batch, position everything, brew a cup etc...
...

A small addendum.
I did this twice yesterday. The first run was just to find out that my BT thermocouple was a bit "oversensitive", so I had to let the roaster cool down and swap the BT and MET TCs. (Which did work nicely btw, the "almost broken" TC does work with steady readings in the MET position without the beans pounding it.)
I found out that it's easier to set the gas at around 1.0 kPa with very little fan and just leave it there for 15-20 minutes. In the latter stage of the preheat I check that even the exhaust bowl and my exhaust hose is warm too.
If you're doing it right, you should be at around drop temp and let the roaster slowly coast down to charge temp, doing the same thing as in between each and every roast.

[PabloElFlamenco]

To me this is a very useful thread...gives me some fingerspitzengefühl (.."feeling in the fingertops sensitivity"... ) cheers!

[edtbjon]

To me this is a very useful thread...gives me some fingerspitzengefühl (.."feeling in the fingertops sensitivity"... ) cheers!

... and that's still only a medium length german word.

[coffee_cat]

Preheat with gas at 0.75 - 1.0 kPa for at least 20 minutes. Artisan on to read temps. Charge at 1.5 - 2.0 kPa.

Fan at 30%. This was arrived at by holding a flame in front of the trier hole. When the flame bends toward the hole, but doesn't go out, that's good starting ventilation.

On charge, gas up as high as 3.75, depending on bean.

[SusanJoM]

+1 to Coffee_Cat's methodology 

[PabloElFlamenco]

I've attached a basic "beginner's roasting guide" which I'll try next roast; I've incorporated Coffee_Cat's recommendations. 
The purpose of this sheet is to [/img][/img]simplify the steps during beginner's roasts, as my experience is that a lot seems always to be happening, leading to confusion...
Any comments welcome!
....Happy Christmas, Peace.ftp://

[edtbjon]

I've attached a basic "beginner's roasting guide" which I'll try next roast; I've incorporated Coffee_Cat's recommendations. 
The purpose of this sheet is to http://[/img][/img]simplify the steps during beginner's roasts, as my experience is that a lot seems always to be happening, leading to confusion...
Any comments welcome!
....Happy Christmas, Peace.ftp://

Well, you probably know that I think that you could rewrite the parts after charge to be more "generic". E.g. you already know that I charge quite low, so that I get my TP at around 75C or so, which in turns renders my DE at around 6 minutes. (As I've written in earlier threads, this approach gives me much better coffee, IMO. I can hit the gas harder and longer, giving the beans much more energy for a longer period of the roast.) Also, I'm not sure about keeping the fan at "very low" until the start of 1C. Last (if memory serves me on this christmas eve...) I never go into 1C with the burner at full blast.

Yes, a little bit of (I hope) constructive critique, I love your initiative. Keep it up.

A Merry and Peaceful Christmas to you all
Björn

[PabloElFlamenco]

Tak Björn...well this is only the beginning for beginners, and I"ll definitely give your remarks proper consideration...when I examine the matter of roasting further.  But you are entirely correct in appraising that I want that "scenario" to be generic!
Greetings!
Paul

[PabloElFlamenco]

This afternoon, I tried applying my roasting scenario, slightly altered to reflext the remarks made by much appreciated board members. 

I hope attached roasting profile reflects those efforts:  in some respects,
I think it does.
TP at 80/175, end roast at 13 mins (why don't my events show up in the saved file?) 

The beans were 400 grams of a Brasil I've been roasting since most of a year and which is our "house" backbone coffee. 
The result shows a uniform and light roast. 
Tasting will be when my Yirgacheffe runs out, in a few days.

How's it look to you?

[navystan]

I preheat for 15-20 minutes with the gas at 1.5, the drum turning, and the damper open.

What I look for is BT, ET and MET to be travelling across the page in parallel.  To me that indicates that the machine is at a stable temperature. 

It's tricky.  The HUKY has so little thermal mass that the slightest change in the ambient temperature, the temperature of the beans being loaded, the wind speed (should you be outside) etc. is enough to make specific settings unreliable.  Every roast will be different because the HUKY itself is just a variation on a tin can.

I like the "KISS" principle.  Keep it Simple, Stupid.  Not saying anyone is stupid, but simple and repeatable is the best course.  In that vein, I like Susan's simple targets and process. 

As soon as I charge, I crank the gas to 3.75 or so and let 'er rip.  Sometimes that is the only change I ever make to the 'settings'.  Usually I make some decreases in the gas somewhere after EOD.