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Hottop - BlueTherm Duo - Roastmaster app  (Read 4570 times)

SQLCPH

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Dear Danny

There is not a doubt in my mind that I want to use your app for my coming roasting adventures on a hottop B-type (just ordered). You have done a fantastic job getting all stats related to coffee into one piece of software - which just happens to look great too :-) Well done...

Before I go "all in" and order the BlueThern Duo and some useless probes I wanted to ask you if you could provide me with a set of rules of thumb or a specific buyers guide for choosing the right BT and ET probe on the Hottop?

I prefer the BlueTherm Duo solution because it enables me a multi purpose use for my BBQ (additional probes)

Your preferred guide for mounting the probes or other users of your Roastmaster advice are much welcome too.

Thank you

/Søren from Denmark (soon to be Hottop roaster)

Danny Hall

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Hi Søren

Thanks for the kind words - great to hear!

The majority of home roasters that I talk to who use the Bluetherm Duo with Roastmaster seem to be Hottop users, so you're in great company.

I'm sorry, though, I've never owned or modded a Hottop myself, so I can't speak from experience here as far as the Hottop installation goes, but I’ll start with the obvious - you'll need K type for the Bluetherm Duo. Standard diameter (in US) seems to be around 1/8 US inch, but whatever makes sense based on the fittings you are going to use (if any). The probes I use for my Quest are a bit wider (around 4mm). They work just fine, but I didn't gain anything from the extra diameter, other than a longer install time :).

For the BT, you need it to withstand the churning of the beans, so a sheathed/rigid type of probe would be the best choice. I prefer ungrounded (insulated) thermocouples. The internal metal alloy junction on these is separated from the sheathing of the probe as opposed to being in contact with it. This protects against ground loop interference from other electrical components (motor, etc) via the metal frame, that could cause wonky readings. It’s worth noting that I’ve never had any problems with either type - ground or ungrounded, and that the insulation of ungrounded probes causes a slightly slower response time. But, I’ve talked to folks who have had problems with interference in grounded probes, and the response time drawback and the slightly higher price IMO beats having to install a ferrite bead or something along those lines to combat interference.

I usually shop for probes at www.omega.com. Don’t limit yourself to probes with the male mini connector already installed (for the Bluetherm Duo sockets), those connectors are readily available and easy to install on probe leads. I get mine at grainger.com, but I’m sure omega sells those separately as well. As for probe length, shop for the best fit for the available space, and where you want the readings to occur within the chamber. Rigid thermocouples measure temps directly at the tip, so the tip should be in the target zone when choosing placement. Many rigid probes are available with braided insulation on the lead wires. I like those because they are more durable (my probes have it) and they are capable of withstanding higher heat than the plastic coated leads. Naturally, the leads are not not for the interior of the roasting chamber, but even outside of the chamber I'm sure the temp gets pretty high, so the extra protection is beneficial.

I did a bit of poking, and there’s a good thread at home-barista talking about probe placement in a hottop. The thread is long, but there’s a number of pictures, and input from a lot of different folks about the best placement for ET and BT probes…
http://www.home-barista.com/home-roasting/installing-et-and-bt-probes-in-hottop-t15145-60.html

Another good resource is a hottop tutorial here…
http://www.frcndigital.com/coffee/HowToHottopTemp.html

Hope this helps. Please let me know if you have any other questions.

Danny
« Last Edit: July 09, 2014, 03:03:15 AM by Danny Hall »

SQLCPH

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Hi Danny

Thank you so much :-) Just the answers I was looking for.

I have made some poking too and found Omega probes to be the thing to use. So I ordered two k-types style 3 and some JB weld. I also ordered a BluethermDuo set so in 2-3 weeks time I am flying with your roastmaster app and a modded Hottop.

I wish you Danny and all the viewers of this happy roasting and a great weekend :-)

Søren from Denmark

Danny Hall

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Happy weekend to you as well! And enjoy the setup - to me that's half the fun. :)

Any questions just let me know.