E61 Grouphead Digital Thermometer & Adaptor
The gizmo arrived Saturday Morning, 7 days after placing order. There was a kick in the breadbasket inasmuch as I had to pay an additional £14 on arrival including VAT (anticipated) but also included (unanticipated) was a Royal Mail 'handling charge on imported goods'.
Installation is a 'piece of cake', takes 20 minutes.
Opening the packet I found, well padded & wrapped the complete assembly together with a set of spare washers, ferrules, temporary closing bolt & a spare battery. Having studied the fitting instructions during the previous week I first off tested the accuracy of the thermometer.
I tested -
a - My body temp
b - Held the probe in the spout of a kettle of boiling water
c - Stood the probe in a small thermos of water & crushed ice.
All three action results were 'spot on' to within +/- a fraction of a degree.
On the thermometer head is a small on/off switch to conserve battery when not in use. Another switch enables readings in Celsius/Fahrenheit. Care will be required when handling these two micro switches.
I removed the plastic probe cover & checked the distance of the probe tip to the base of the drilled screw threaded bolt. This must protrude 3/8ths inch.
Next I finger tightened the thin 11 mm nut to hold the thermometer in place at the correct distance.
So far so good - now to install.
Undid & removed the Allen key nut on the grouphead. Inserted the adaptor assembly complete with supplied copper washer & screwed in finger tight. Used an 11 mm spanner to tighten the nut with a 45 degree turn, Turned the thermometer head to the correct orientation & tightened the thick 11 mm probe nut, also with a 45 degree turn.
That was it - installation completed.
Take note that the Indicated Celsius reading is approx 1.25 degrees C hotter than at the puck in the PF.
Filled the water tank, switched on & left to heat up 10 minutes looking for any leaks around the fitted probe. Bone dry!. Locked on the PF & drew water through for 30 seconds. Finally fitted a blank PF & back flushed for 15 seconds twice. No sign of leaks or seepage around adaptor, a perfect fit!
I set the pstat at max 1.1 to give an idle reading at the probe of 102.5 C given that Vivi is switched on approx 1 hour before first use.
Same beans, roasted to same level used throughout.
I have been trying 2 different approaches
a - Looking first at my usual method of waiting for the 'water dance' (approx 5ozs/20 seconds) the temperature at the probe shows 99 degrees C (97.5 at the puck) falling. I then load & lock the PF (approx 10 seconds) & lift the lever to brew a double shot for 25 sseconds. The temp spikes up to 102C (100.5 at the puck) & then moves downwards to 95 degrees (93.5 at the puck) on completion. The brew cycle is taking place during a falling temp at the puck of 100.5 down to 93.5.
b - Longer method
1 - Load & tamp PF. - keep ready.
2 - Cool flush to 92 deg.
3 - Stop the flush & load PF. The temp spikes up immediately to around 95/96 then slowly drops back. to around 94 deg & then starts to rise again. 'Reverse Thermosyphon Action'
4 - At this point as the temp now starts to rise I raise the lever & start the shot. During the ensuing 25 brewing seconds the temp shows a steady 97 deg (= 95.5 at the puck). The brew cycle takes place on a rising temp & stays steady during the brew at 95.5 degrees Celsius If I continue to make shots within a few minutes I still cool flush down to 92 deg but the draw off is much less & 92 deg is reached very quickly.
The taste difference between method a & method b is very subjective. Maybe I can just discern a slightly fuller flavor with b.
My own conclusions are that it’s a great tool, very well engineered, easy to fit & most importantly gives me a consistent result every time based on using the same beans roasted to the same level.
It is very useful to be exact with the follow on brews after the initial start whereby it takes differing amount of flush dependent on time interval. Always going back to a base starting temp keeps things very consistent .
Knowing what I now know, would I buy again at a total current (October 2007) price of £66 including the sting in the tail? - For me, an emphatic yes.
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