henrikc Senior Member Joined: 28 Aug 2003 Posts: 6 Location: Copenhagen Expertise: I love coffee
Espresso: Izzo Vivi Grinder: Mazzer Mini B Roaster: Quest M3
Posted Fri Feb 8, 2013, 4:03am Subject: New 230V Quest M3, drum temperature, ET and BT, vs commercial drum roasters?
Hi, I am roasting Brazilian Fazenda Rainha for espresso to get to know my new M3 better. Made a test today during pre heating, in an attempt to see the temperature versus amps in the empty roaster.
This M3 was just received from Taiwan, and different to what I have read of the roaster, mine runs the fan with a gentle draft even when the fan setting is on 0. During a roast, so much draft indeed, that I do not find it necessary to increase the fan speed to get the chaff out of the drum, as it collects nicely in the filter chamber on the minimum setting.
@ 3,50 A, the BT thermocouple settles around 195 C (383 F), while the drum temp measured with an infrared thermometer through the (quickly opened and closed) bean exit reach around 240 C (464 F) @ 3,75 A, the BT shows 213 C (415 F) while the drum is around 265 C (509 F) @ 4,00 A, BT shows 230 C (446 F), drum 300 C (572 F)
With the fan on zero, the ET shows 7 to 10 deg C (47 F) lower than the BT in the empty roaster! If I remove the fan action by opening the cooler lid, @ 3,00 A, temperatures find an equilibrium for BT at 216 C and ET at 228, while the drum is around 280 C.
Measurements with thermocouples are made with two Victor 86C DMMs and the supplied type K thermocouples located in an open end 4mm thin walled brass thermowell l some 50 mm into the drum from the front flange back side through the pre drilled holes. (They show less than ½ degree difference when measuring the same temperature.)
I wonder how the relation between drum and ET compares to full size drum roasters and commercial sample roasters? Do the full size roasters draw cold air into the drum too, or are there means to pre heat the draft?
To give an idea of a roast diagram, I include the 200 g batch roasted after the temperature test above, beans were loaded at about 195 deg C while the drum was 238 C: power 4½ A to 180 C, then 3½ A to end of roast; fan on min. as suggested in the new 230V manual for an "advanced roast" 1.Cs 8:16 186.3 C (367 F) 1.Ce 10:20 198.2 C (389 F) SCs 12:59 206.4 C (404 F) End 13:21 207.5 C (406 F) I trust I see slight tipping....is this bean prone to this?
Looking forward to your answers and comments also to the somewhat awkward ET shown...... Thanks Henrik
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,151 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Fri Feb 8, 2013, 6:59am Subject: Re: New 230V Quest M3, drum temperature, ET and BT, vs commercial drum roasters?
My Diedrich 1kg machine bring takes air into the drum from the roasting chamber so it is pre heated, the larger models have heat syncs to further preheat the intake. My machine weighs 130lbs so has a lot of thermal mass that needs a 30 min warm up especially in colder temps.
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