I'm sharing my latest and best profile so far because it answers several questions I/we had about Hottop-B roasting. Some of which are:

1. What about the HT fan?
2. How do my roasts compare to US artisan roasts?
3. How do you do softer beans on the Hottop?
etc!

Let's address #2 1st: I got lucky recently and was able to secure a good amount of fresh espresso blends from Stump Town, Paradise Roasters and a third good(but not top tier) US roaster. Comparing my recent roasts of SO espresso VS artisan espresso blends I conclude we're definitely on the same league. No, this isn't an argument for home VS pro, it's just a reassurance of how well I'm doing. So now I know I finally roast great espresso, let's proceed.

On to the fan: the HT fan sucks fresh, room temp, air and exhausts it. With fan on OFF, you have a roasting system mainly controlled by how hot the drum(& surrounding air) is and what power the heater is at; i.e. a pretty stable environment that's easy to understand. Now, if rapid fresh air movement is introduced to this system, control gets tricky. As the roast progresses, the drum+other parts should get hotter BUT they'll be hit with that cool, room temp, fresh air; loosing heat in the process while the fresh air gets heated -- BUT that air leaves the system in a second AND hits the beans on it's way! So, now you have an ET that's pretty tough to figure out AND heating elements that are hard to control: if you go high heat, you could get your ET too hot, if you go low, you lower your ET -- both result in less-than-great roasts.

So what's the solution? Either recirculate that hot air or stop that fan completely.

I insulated my HT(nothing fancy, but it works for now), stopped using the fan and I'm now roasting with profiles that look like this:

The new results are clearly better than anything I've done before; I still need to tweak the tight turns etc but no change to the approach. Here's what's very clear so far: my roasts are now livelier, my HT is now even more profile-able and I now have a firm grip on what temps surround my beans.

With the insulation and no fan, I can go lower charge temp, lower max heat and my softer beans suffer no defects. Another nice side effect is that I can now take my regular beans darker with no ashy taste.

It's all good, and I'm glad my roasts are finally confirmed equal to established artisans, now I'm happy to have you join the celebrations .

Next? Probably trying to go above a 113g batch size

Nice to have confirmation after all these years that, in a HotTop, the fan sux.

You may want to try keeping P constant for darker roasts.
For the darker PNG component, ~440°F, for the 'house blend', I keep power constant after the reduction before 1c.

Max

I agree that the fan has limited use in controlling my roasts especially now that I am roasting in colder temperatures out on the back enclosed deck. However, your power levels in the UK seem to be higher then I can get (120V during roast) and you appear to have lots of reserve heating capacity. So, why are you limiting yourself to 113 gm roasts? I think I would quit roasting if I had to go back to popper-type loads. Why not use a load that requires 8-9 power settings with the same heat ramp and profile?

I'd take my "A/A+" 113g roasts over my "B/B+" 225g ones anytime of the week, taste matters more to me.

You can still try my approach above: insulate your roaster, stop your fan, preheat for 5 more minutes on low power, drop in a small load, use lower power throughout and see if you like the outcome. There's nothing especially special about my setup: my HT is the US version running on a 130V outlet, if you're running yours at 120V, my P=6 is probably your P=7 or 8.

I believe my lower power, smaller batch, roasts are superior to the few hundred high power, bigger load, ones I did earlier. On another thread, you can see me trying to figure out the HT MET and the effect of the heating element power on the roast -- beyond just going faster or slower. On this one, I'm quitting fan use and I roast FAST even though I use only low power. I might try to tackle bigger loads eventually, but I'll not compromise what I learned about roast taste in the process.

Max

You misunderstood my reply. I don't question your taste and the newer profile giving you better results. I am asking if you can reproduce it with a higher load of beans. You start at 20' with a power of 6 and go DOWN on power from there on. Have you tried 200 or more gm but start at 8 or 9 and go down from there on. I don't see why that might not give the same profile but of course I could be wrong.

Could you share how you insulated the HT?

THanks for sharing your results. It is appreciated.

No, thank YOU Geoffrey for the questions, you're helping me clarify what I wanted to share.

If my reply sounded defensive, it's because I'm keen on communicating an important point: profiling is about the whole roasting environment, more so than just about the power & fan levels. We simply can't measure everything the beans react to. That is, I now believe that the fan should be on OFF, therefore, a little bit of air makes it a VERY different profile. I now believe the beans should not get close to a very hot element, therefore, I can't go too high with power just because I want to increase batch size. etc. All this is part of the profile.

I might want to tackle bigger loads eventually, but I can't imagine going beyond P=7 as I already believe that a larger load with P>7 results in roasts of lesser quality than what I have now due to the beans being exposed to a higher MET(due to closeness to the element and increased power). Some beans can take the extra MET but others for sure can't, I'd rather delay dealing with that extra variable and roast twice!

On the fan, again, my fan-less roasts are better, but my LCD gets foggy because of the trapped smoke during a fan-less roast; i.e. there's motivation to use the fan. But, a little fan introduces fresh air making for a non-predictable, hard to measure, MET and therefore less controllable, lower quality, roast. There could be other effects to using the fan, but my fan-less roasts are better -- I ditch the fan till I understand more.

Our little roasters have limits, we find them, we work within them, and we are rewarded with artisan-like coffee. . . . if we don't, we don't!

I'm open to better ideas and I'd love to hear from people who can give this profile a go, or three!

GC7 wrote:Could you share how you insulated the HT?

I don't have access to a good material so I used duct insulation. I covered all the external stainless with it; covering all holes except the bean chute and external openings behind the element.

Got it Max - thanks for that update. Your hypothesis about the power and environment surrounding the roasting beans makes sense.

I've used your 150-175 gm profiles modifying the power levels to my 120V home but I didn't find them an improvement on my 225 gm profiles. I'll give this one a shot when I have a bit of time with some beans that I am really familir with roasting and tasting.

With a bean that can take the heat, I modified my latest "profile" for 170g. This bean also needed a longer drying time, so I lowered the charge temp a bit. This was a fantastic SO espresso roast by all means but it followed the same principles: lowish load, no fan, extended preheat, no high heat; all on an insulated HT.

Hello,

First of all, great post! I might go in the same direction...

I have a few questions/comments related to your insulated HT.

Did you ever mesure the surface temperature of the HT just behind the heating element? That's certainly the highest external surface temperature area. I wonder how high it goes around that time when you lower the heat from P6 to P5.

What material is your duct insulation good up to +450F or more?

I found two materials:

A) High-Temperature Sheeting up to +1000F. A piece of 24"x96"x1" is ONLY 14$ (1" 1/2 thick is 21$). This material is used in industrial furnaces (McMaster 9356K11 and 9356K12). Meets ASTM E84 25/50 for flame and smoke.... would prevent smoke to come out ; - )
B) Fiberglass paper +1200F. 16" x 10' x 1/8" is 23$ (McMaster 9323K21).

Last, how do you cool down your HT? Did you add a toggle switch to keep the fan running? Gotta find something to do with that fan!

Thank you,
PB