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  • Equipment to measure brew temperature

    Now that I know that I can adjust the pressurestat setting and the brew pressure in my machine, I would like to go to the next step and get the brew temperature water at the optimum temperature, by measuring rather than guessing.

    Can anyone recommend what gizmo I would need to get the job done...or be able to refer me to where it has been mentioned before here in Coffeesnobs?

  • #2
    Re: Equipment to measure brew temperature

    there are a few options

    cheap and dirty...DMM with wire type thermocouple snaked under the group while pulling a shot.

    downright expensive SCACE thermofilter but accurate. Used at competitions to calibrate machines.

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    • #3
      Re: Equipment to measure brew temperature

      Thanks, Wushoes.

      Do you have an idea of where I could look out for these options and their approximate costs?

      Pardon my ignorance but what is a "DMM"?

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      • #4
        Re: Equipment to measure brew temperature

        Digital Multi Meter. I got one from Jaycar for under $50 (I think) that data logs straight to my laptop too...so you can actually profile temperature stability...just export the data in to excel and graph it.

        I have the Digitech RS-232 Auto range DMM...CAT: QM-1538

        RS-232 means serial cable transmission...Auto ranging means you dont need to select the units, the DMM will do it automatically.

        Grab a wire type thermocouple while youre at it.

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        • #5
          Re: Equipment to measure brew temperature

          Originally posted by Wushoes link=1183624026/0#3 date=1183626000
          Digital Multi Meter. I got one from Jaycar for under $50 (I think) that data logs straight to my laptop too...so you can actually profile temperature stability...just export the data in to excel and graph it.

          I have the Digitech RS-232 Auto range DMM...CAT: QM-1538

          RS-232 means serial cable transmission...Auto ranging means you dont need to select the units, the DMM will do it automatically.

          Grab a wire type thermocouple while youre at it.
          Wushoes

          I have one too but just have the standard stick-type thermocouple.

          Did you manage to get a wire-type TC that plugs straight in, or did you have to modify the connections?

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          • #6
            Re: Equipment to measure brew temperature

            it just plugs straight in

            I use it to profile my coffee roasts and to give a secondary reading to see what the temperature difference is between the PID and DMM.

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            • #7
              Re: Equipment to measure brew temperature

              Thats too bad (for me)

              The only wire-type available at my local Jaycar has smaller pins at a different spacing. I am unsure whether modifying it by snipping off the connections and soldering on some new banana pins would affect the readings it takes.

              Whats the chance you could advise me the brand / model of your wire-type TC for me to chase down, Wushoes?

              Theoretically I should just handball the problem to the Jaycar staff but bitter experience has shown me that the pimply youth behind the counter will give me a blank stare....

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              • #8
                Re: Equipment to measure brew temperature

                Meetim -

                I just ordered one of these (link will take you to an eBay auction):

                http://tinyurl.com/2no4un

                It is an adapter that will allow the use of K t/c mini-plugs on a DMMs terminals. The one I ordered is advertised to fit a Fluke DMM, but I think the banana plug sizes and spacings on DMMs may be universal.

                Jim

                PS - I have no affiliation with the folks who sell these, just passing along (hopefully) helpful info

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                • #9
                  Re: Equipment to measure brew temperature

                  Im using an "Erics E61 thermometer adaptor" You need an E-61 brewhead for this, but it just screws into place and measures brew temp. It works great and is a very well made piece of kit. Has improved my shots out of sight, I can now hit a target brew temp within 1F 90% of the time.

                  Ben

                  PS. Cost me about $115 delivered to my door from memory.

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                  • #10
                    Re: Equipment to measure brew temperature

                    Howdy All,

                    The wire type thermocouple from Jaycar is part number QM1284.

                    Regards,

                    Karl

                    Comment


                    • #11
                      Re: Equipment to measure brew temperature


                      Thanks for your advice, chaps

                      Ive managed to buy a wire-type TC from Jaycar that plugs right into my QM-1538. (easy if you pick the right Jaycar)

                      Its not a QM1284, its a Quadratech MS3400 (noted on the unit itself not the packaging). cost - $10.

                      I have measured the brew temp at the PF outlet of my EM6910 while just running the water through (no coffee inside). its a bit tricky as it exhibits a temp degradation over time, so the temp measured was the max temp acheived during the run. Temp was measured on min, mid & max espresso thermoblock settings.

                      Min - 81degC
                      Mid - 84degC
                      Max - 87DegC

                      This is a little disconcerting as the manual states on p34 "the water temperature of this espresso machine has been calibrated to the precise temperature of 92degC at the group head".

                      I have just posted my preliminary results for info. I am not going to wax lyrical on temps here as it has been discussed at length in another topic.

                      http://coffeesnobs.com.au/YaBB.pl?num=1177174323/0#0

                      RS232 recording is going to be interesting given the lack of a laptop. Visualise an espresso machine set up on my study desk next to my desktop computer.

                      Comment


                      • #12
                        Re: Equipment to measure brew temperature

                        Meetim, those figures would be worrying....but are you sure you did it right?

                        Placing the thermocouple bead under the shower screen and releasing water will not be accurate. You have to simulate as much as posible actual brew conditions.

                        That is, a portafilter in place, pre-warmed of course, and the bead sloshing in flowing water for the 25-30 seconds it normally takes to brew.

                        Allowing air onto the bead will give a false reading as the air is probably 70 degrees cooler than water.

                        Having the bead in contact with the shower screen will also cause a wrong reading as it is outgoing water you want to measure, not the metal fittings.

                        Placing the bead in a cup on the drip tray will be about THE most inaccurate as the water will have fallen through the cold air and cooled several degrees (not to mention the cold cup also cools it).

                        I use a pre-heated cut down polystyrene cup with the t/c fed hrough a hole near the top so the bead will be slightly below the shower screen.

                        Water will collect in the cup but will not lose calorific value because of the cups insulating properties.

                        Aim for 92 -95 degrees.

                        Others place the t/c over the lip of the portafilter and then screw the pf onto the group as per usual. I find this wears down the thermocouple and there is no guarantee it will be saturated by water constantly finding its small target as it exits he shower screen.

                        --Robusto
                        --Robusto

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                        • #13
                          Re: Equipment to measure brew temperature

                          The thermoblock requires a proper espresso extraction to reach those temperatures...it requires the flow rate to be correct for the temperature to be correct as pointed out in other threads

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                          • #14
                            Re: Equipment to measure brew temperature

                            Very true shoes,

                            If possible, it is best to load & tamp a basket as if youre going to pull a normal shot, place the t/c bead on top of the puck then carefully lock the PF into the Group, maybe a little tighter than you would normally do it to make sure the gasket seals around the t/c cable properly.

                            When you and machine are ready, pull your shot as per normal and record the temperature profile over the course of the usual 25-30 seconds of a shot. This is the next best way of recording the temperature as accurately as possible without having access to a special purpose built PF. Ive completed several tests in this way and even though the t/c cable ends up with a bit of a kink in its tail, after about a dozen tries its still in good nick.

                            Cheers,
                            Mal.

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                            • #15
                              Re: Equipment to measure brew temperature

                              An alternative is to make a hole in a basket and then feed the TC wire up through the PF spout and through the hole and then tie a knot in it so it cant be forced back out. Near the edge would be best so that the wire hole isnt surrounded by extraction holes on all sides.

                              Outside the PF, the TC wire needs to loop upwards so that espresso doesnt leak all over your bench.

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