New Hottop owner

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
larrypt
Posts: 5
Joined: 10 years ago

#1: Post by larrypt »

I recently took the plunge and upgraded my Behmor to a used Hottop B2-K. I have to say that being able to turn the heat down at first crack is satisfactory (to say the least). I had OK results so far but I think I might have stalled the roasts quite a few time. It is a little hard to see what is going on after first crack with the stock probe and I will be installing BT and ET probes along with the TC4C/HTC to be able to measure/record/control. I had a few questions before I start:

- My voltage is OK right now (120V w/o load, 115V with Hottop), but during the summer/winter it can easily go down to 110V with no load and 105V with a load. I live in a old building (1900), so the 5V drop seems to be due to old wiring. I was thinking about finding a Variac to stabilize my voltage, but I have read somewhere that the Hottop is insensitive to voltage. If the 120V is directly supplied to the heating element (at 100% heat), it would seem like a ~5% voltage drop would result in ~10% power drop (heat per time unit), while a ~10% drop would result in ~21% power drop (V^2/R). What are your experiences with recent Hottop and low voltage?

-It seems like there are many different good ways to install the BT/ET probes. I'm planning on installing glass braided beaded probes from Omega, threaded through high temperature food grade silicon tubing, held by 1/4 '' brass sleeves (similar to what has been described in many threads like this one TC4 + HTC roast controller for Hottop available) I would seal everything with high temp/food grade silicon sealant (instead of JB Weld), so that it is reversible. Any comments on this setup?

- Anyone found a use for a third /MET probe in the Hottop? I was thinking about installing a probe close to the element and drum (similar to BT but on the opposite side), since it seems like this would be where the beans are exposed to the highest temperature.

- Finally, what does a stalled roast taste like? Just bland? I have a few fermented DP roasts which I haven't had before (maybe bad beans?). My roasts so far have been something like 6/5-5:30/2:30-4 (charge to 300F/ to 1st C/development) to city+/full city with 225g. I was hoping to lower my load to have better control but waiting to have installed the probes since the stock one will be useless at lower charge.

Sorry for all the questions and thanks for your help!

Larry

PS. The amount of information found on this forum is just fantastic!

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JohnB.
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#2: Post by JohnB. »

With the voltage readings you are seeing you definitely NEED a variac. Despite what it says in the manual your less then ideal to down right low voltage will have a big effect on roast times.

I see 117v at my outlets & was able to trim 2 minutes off my 1c times by running the HT through a variac set to provide 120v during the roast. Couldn't imagine what your roast times would be if you start with 110v & drop down to 105v.

With a variac providing ideal voltage you will have plenty of control with 227g loads especially if you replace the barn door rear filter element with a stainless screen.
LMWDP 267

Barrie
Posts: 43
Joined: 14 years ago

#3: Post by Barrie »

Have a look at post #21, by Ciel-007 in this thread in the HRO forum

http://www.homeroasters.org/php/forum/v ... post_50624

And welcome to the HT community. In response to one of your questions, stalling a roast just means that you have allowed the Rate of Rise in the chamber to slow so much that it has gone negative, i.e. the bean mass is not increasing its temperature or is actually decreasing. I can't imagine that happening unless the homeroaster has not been paying attention for some considerable period of time. The more likely scenario would be to slow the RoR to zero or just above. The taste of the beans would then depend on the stage of the roast at which you brought this about, and how long you let it stay there. There is no unique taste, therefore?
Incidentally, although I am a great fan of computer control and logging, using Artisan in my case, if I had to pick one component that I find most useful, it would be monitoring realtime RoR during the roast, especially from just before 1C and thereon.

Barrie.

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ciel-007
Posts: 61
Joined: 10 years ago

#4: Post by ciel-007 »

larrypt wrote: ... voltage during the summer/winter it can easily go down to 110V with no load and 105V with a load... I was thinking about finding a Variac to stabilize my voltage, but I have read somewhere that the Hottop is insensitive to voltage...
Larry, regardless of what the manufacturer may claim, the Hottop is quite sensitive to changes in line voltage.

Voltage in my wall plug frequently shows 118vac, and that translates into approx 715 watts of roasting power in my Hottop.

However, when a Variac is employed to boost input voltage to say 129vac, that enhances my Hottop's roasting power to about 850 watts.

Bottom line - a Variac does indeed make a huge difference in your Hottop's roasting performance.

Fern

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rama
Posts: 344
Joined: 15 years ago

#5: Post by rama »

Welcome Larry. In the future I suggest you post one question per thread.

As has already been said, the Hottop is quite sensitive to voltage. Unless you're certain all outlets in your place are the same voltage, get a Kill-a-Watt (http://www.amazon.com/P3-P4400-Electric ... B00009MDBU) and find out for yourself. Its good to have anyway going forward because you should adjust batch size based on the day's voltage. If that doesn't solve the issue, you can then look into a pricey variac. (I haven't needed one myself using this technique).

As for probes, I've been fine with BT and ET only.

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ciel-007
Posts: 61
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#6: Post by ciel-007 »

larrypt wrote: ... Anyone found a use for a third /MET probe in the Hottop? ... The amount of information found on this forum is just fantastic!
Larry, the most important probe of all is the one that monitors the changing BMT. Although I continue to believe that the Hottop is arguably the best home roaster available, it does have its share of design flaws. Some of those flaws, and what possible steps might be considered to redress them, are discussed at the attached link:

http://homeroasters.org/php/forum/viewt ... post_42291

Fern

larrypt (original poster)
Posts: 5
Joined: 10 years ago

#7: Post by larrypt (original poster) »

Thanks for all the replies! And sorry for dumping all my questions into this thread, I didn't want to flood the forums with my newbie questions...

From the numbers quoted in this thread and the one referenced, it seems to confirm my intuition that at 100% the voltage is directly applied to the heating element. Therefore, a small drop in voltage results in a significant drop in power (P=V^2/R). I will be trying to find a reasonably cheap US-made Variac.

Thanks for clarifying about stalling the roast. This is about what I meant, for the first couple of roasts I was surprised by the 1C and tried to slow down the roast too much... Quite often the display temperature would stay constant for a while... But it is hard to say exactly what is going on since the Hottop temperature sensor is much less sensitive than a BT probe after 1C.

It make sense for now to just install BT and ET. Maybe if at some point I feel like I need more data I will try MET (gotta use those inputs in the TC4C!). I just need to convince myself to drill holes in my Hottop now!