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Thread: water temp. coming out of group head

  1. #1
    Senior Member summercrema's Avatar
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    water temp. coming out of group head

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    what is the acceptable range of temp. for water coming out of the group head, I presume boiler temp is higher, group head is lower as water has to travel through pipes before getting to the group head. I have a expobar minora II, the boiler is 94c and the water from group head is 82.4c. is that pretty much the right temp. for the group head water?

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    Re: water temp. coming out of group head

    Exactly how are you measuring the temperature? Hot water loses a lot of heat energy as soon as it is removed from the heat source and exposed to air, particularly when it is "pouring" through the air.

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    Senior Member summercrema's Avatar
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    Re: water temp. coming out of group head

    I catch the hot water right under the group head with a preheated 150ml cup then measured it with two different digital thermometers, basic $20 thermometer, one has a reading of 81.second crack other has a 82.4c.

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    Re: water temp. coming out of group head

    My advice is not to let all these endless academic discussions in these forums interfere with your coffee enjoyment. To that end, if you are making good coffee, forget about what you have been trying to measure.

    Laymans explanation: While the PID display is telling you the brew temperature you have set, it is actually not reading that at all....it is actually reading the much higher temp in the boiler & working backwards to give you the theoretical calculated brewing temperature at the outlet of the group head.....formula as worked out by the design and build engineers.

    That is one thing.

    The other thing is that I guess you are not reading the brew temp in the right way, which is basically not to let the ambient air come anywhere near the temperature probe (or it will cause you to obtain a false reading.

    By far the easiest / reasonable method of doing this without building or buying the proper device, is to "screw" a takeaway cup into the group ring (where you insert the group handle) so it is hard up against the seal, and poke a hole into the cup just enough for the temperature probe to slide in. Then flow the group.

    If your thermometer is not an instant read type, you should pre heat it in a cup of hot water, and go straight from there into the hole in your takeaway cup, so the "lag" wont be as big as you try and measure. *

    That should get you a much closer temperature reading, to what you can see on the display.

    If your PID display is reading 94, then that is the "calculated" temperature of the exit of the group as explained above. If all is working as it should, your 82 degree reading is an incorrect temperature indicated through not measuring in the correct manner.

    In any case, the temperature will also fluctuate depending on what part of the cycle you are on, how many coffees you have flowed (or not), and how sensitively the P-I-D is set for response and recovery, power to the element, how the display reading is damped, etc etc etc.

    After that, you dont know what the manufacturer deems to be an acceptable fluctuation, so even if you did manage to accurately measure the water coming from the group...what does that mean?

    Trust me....dont go there.

    As already stated, chuck the thermometer away and enjoy the coffee.

    Regardz,
    Attilio
    very first CS site sponsor
    Long Live well designed and built HX machines.*







  5. #5
    A_M
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    Re: water temp. coming out of group head

    Quote Originally Posted by 5F594141495E4F5E49414D2C0 link=1275273670/2#2 date=1275276435
    I catch the hot water right under the group head with a preheated 150ml cup then measured it with two different digital thermometers, basic $20 thermometer, one has a reading of 81.second crack other has a 82.4c. *
    If ya look at the Em6910 topics ya will see this asked time and time again..

    Ya method is not good enough and prone to too many variables / errors.

    And further more; unless you chasing a major issue with whats in the cup AND THAT the symptoms are that typical to significant temp issues... Dont go there..

    More about flow rate and beans and grinders and USER than temp..

    KISS = See comment below.

    Quote Originally Posted by 6A5E495F44736F434A4A49492C0 link=1275273670/3#3 date=1275277287
    As already stated, chuck the thermometer away and enjoy the coffee.

    Regardz,
    Attilio
    very first CS site sponsor

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    Re: water temp. coming out of group head

    Quote Originally Posted by 7C7A62626A7D6C7D6A626E0F0 link=1275273670/2#2 date=1275276435
    I catch the hot water right under the group head with a preheated 150ml cup then measured it with two different digital thermometers, basic $20 thermometer, one has a reading of 81.second crack other has a 82.4c. *
    METHOD ONE:
    Lets look at this method from another direction. Take a measuring cup and put it in the microwave and get it to boil. Thats 100 C. or a bit less depending on altitude, water make up, etc. Then pour water from that vessel into the same preheated coffee cup you have been using, from about the same distance above the cup, and measure that temperature.

    Now take the thermometers and test them in the boiling water as well as in water with ice and a bit of salt to get as close to ) C. as possible. use the error to compensate for teh data you have collected above.

    METHOD TWO:
    Drink the espresso. When it tastes about the same every day for a month or so indicating that your procedure is sound, adjust the pressurestat a LITTLE one way or the other and leave it there for a week or so and see how that works for you. Repeat with other adjustments until you find a taste you like. When you change coffee suppliers, repeat. Get back to us with your results in a decade or so... ;)


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    Re: water temp. coming out of group head

    I am having trouble with too much sourness, not enough crema thickness from my vibe pump HX e61 machine, and a temp probe from a thermocouple thermometer shows 82 degrees, when inserted on top of the dead puck from a shot just drawn, reinserted into the grouphead and further water is drawn straight through. My OPV is set to 11.5 bar.

    So maybe too low a temp and too high a pressure?

    The OPV is being replaced soon to get me closer to 9 bar-I might also ask for the boiler pressure to increase to get a higher temp.

  8. #8
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    Re: water temp. coming out of group head

    Quote Originally Posted by 7771696961766776616965040 link=1275273671/2#2 date=1275276435
    I catch the hot water right under the group head with a preheated 150ml cup then measured it with two different digital thermometers, basic $20 thermometer, one has a reading of 81.second crack other has a 82.4c. *
    Waste of time! The flow rate through the group head is much higher without a packed bed of coffee in its path, so youll get a different temp to what youll get when pulling a shot.

  9. #9
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    Re: water temp. coming out of group head

    Behmor Brazen - $249 - Free Freight
    Quote Originally Posted by 2B3E313136315F0 link=1275273671/6#6 date=1284889634
    I am having trouble with too much sourness, not enough crema thickness from my vibe pump HX e61 machine, and a temp probe from a thermocouple thermometer shows 82 degrees, when inserted on top of the dead puck from a shot just drawn, reinserted into the grouphead and further water is drawn straight through. My OPV is set to 11.5 bar.

    So maybe too low a temp and too high a pressure?

    The OPV is being replaced soon to get me closer to 9 bar-I might also ask for the boiler pressure to increase to get a higher temp.
    Just tried this again and got 93.8 degrees-when letting the machine idle for an hour- so spot on. No cooling flushes needed. Just longer warm up time.



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