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M27 dead band and boiler pressure setting

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  • M27 dead band and boiler pressure setting

    Hi all,

    Just fitted a new element to the M27 and have adjusted the pressurestat for the following results:

    0.85 to 1.1 bar, on the boiler pressure gauge

    190 seconds off, 24 seconds on. (with the covers off...)

    Is this dead band ok for the pressurestat, or would it be less for a better / new one? Its still got the cimbali pressurestat, that I think is the original.

    Any recommendations for what I should have the boiler pressure set to?

    thanks.


  • #2
    Re: M27 dead band and boiler pressure setting

    My M28 2-group Basic runs from 1.025 too 1.275 with the original(?) 20 or so year old pressure stat.

    The duty cycle is at 15% (36s on and 204s off) now that Im into the 16C winter time temp in the house as opposed to a 12.5% duty cycle during the warmer months when the temp in the house is 22-26C.


    Java "Still loving his Cimbali!" phile
    Toys! I must have new toys!!!

    Comment


    • #3
      Re: M27 dead band and boiler pressure setting

      Thanks Javaphile for the info.

      Do you have the 2850w or 3750w element?  (mine is the 2850)

      Wow, u must have a detailed gauge or good set of eyes to read the pressure down to three decimal places....

      Roughly, 1.0 to 1.3 is where mine was set before I started adjusting it back.   I read somewhere that the top end should be set to a max of 1.1, but to be honest I have no idea what is a good setting on this machine.

      I guess the temp & pressure in the group head, and taste will be the test.  

      Hopefully the loaner pressure gauge from Greg will arrive soon and I can do some more testing to see whats happening at the group head.

      Comment


      • #4
        Re: M27 dead band and boiler pressure setting

        Originally posted by 363B263520656667540 link=1256554177/2#2 date=1256611255
        Do you have the 2850w or 3750w element?
        I have no idea. The info tag on my machine is no where to be found. Id love to know what my unit draws!

        Originally posted by 363B263520656667540 link=1256554177/2#2 date=1256611255
        Wow, u must have a detailed gauge or good set of eyes to read the pressure down to three decimal places....
        My gauge has graduations of .025 bars.


        Java "Squinting at the gauge" phile

        Toys! I must have new toys!!!

        Comment


        • #5
          Temp at the group head

          Ive been trying to measure the water temp at the group head. I used a temp probe with the CS multimeter and just stuck it into the water flow inside one end of a double spout.

          Got some very low temps with the boiler pressure set 0.8 - 1.1, so reset it back to 1.0 - 1.3.

          With the boiler pressure reset, one group head was about 89, and the other about 87. This was when first opened as the steam and overheated water bubled out. Temp was reducing from that point onward.

          Has anyone else tried to measure temp from this spot and got 93 degs, or should there be some allowance for cooling by the time the water gets to the spout?

          PS. The hotter group head produces a nice shot, and the other one almost chokes with exactly the same grind. I suspect the other one might need the pumps OPV valve adjusting (?).

          Comment


          • #6
            Re: Temp at the group head

            Originally posted by 3934293A2F6A69685B0 link=1256554177/4#4 date=1257487312
            Ive been trying to measure the water temp at the group head.   I used a temp probe with the CS multimeter and just stuck it into the water flow inside one end of a double spout.

            Got some very low temps with the boiler pressure set 0.8 - 1.1,  so reset it back to 1.0 - 1.3.

            With the boiler pressure reset, one group head was about 89, and the other about 87.   This was when first opened as the steam and overheated water bubled out.  Temp was reducing from that point onward.

            Has anyone else tried to measure temp from this spot and got 93 degs, or should there be some allowance for cooling by the time the water gets to the spout?

            PS.  The hotter group head produces a nice shot, and the other one almost chokes with exactly the same grind.  I suspect the other one might need the pumps OPV valve adjusting (?).
            Pretty much a waste of time without a Scace device Borat: http://www.espressoparts.com/cgi-bin/ep.pl?pgm=co_disp&func=displ&strfnbr=71&prrfnbr=50 05&sesent=0,0&search_id=72934

            2mcm

            Comment


            • #7
              Re: M27 dead band and boiler pressure setting

              USD$500..... ouch

              If someone who has measured and set up the temp in the group head properly, I was wondering how different the temp would be if measured in the spout, with the basket empty.....

              Comment


              • #8
                Re: M27 dead band and boiler pressure setting

                I have played the temp games using a TC and my PID as a reader, i aimed for 93 by doing a pre flush of say 1 double 60ml then insert loaded GHandle and make shot. This way i sort of no that after a flush i will get about 93. i have volumetrics so it is preprogramed to get the double, then i just go by sight for the actual shots.

                I had the TC under the shower screen and loooked for a 93 in the middle of the shot.

                The issue with this is that it is just running water not a puck and what might happen over 30 secs. I next want a naked handle then will drill a hole in a basket maybe a blind to make a better temp "scace".

                I made my own pressure gauge set up to make sure the Ghead was at 9bar ish.

                Comment


                • #9
                  Re: M27 dead band and boiler pressure setting

                  How about blanking off the group handle, at the spout thread. Drill the blank with a hole to feed the wire up through to the basket. The basket also has a hole and the wire ends up sitting in it.

                  The hole in the blank restricts water flow acting as a choke so the basket & handle fill with water, and temp can be measured. Hopefully with water flow not too different from what would happen with a basket full of coffee.....



                  Comment


                  • #10
                    Re: M27 dead band and boiler pressure setting

                    yeah i like your idea,

                    i was thinking a naked so i could leave the TC in it and drop it into any 58mm naked group handle to share it around other CSers

                    but i need to use a little box for the PID and then have a plug on the TC &box as the PID is 240 and needs to be "safe"

                    it could then be sent with the pressure gauge and adapter for a "scace" type set up. Using a normal GH means it is sort of "fixed" to one GHandle and then is not a fits all

                    i have never used a TC and multimeter how fast does it react? the pid is very fast to read changes

                    Comment


                    • #11
                      Re: M27 dead band and boiler pressure setting

                      Just eyballing the temp rise and fall, it seems to react quite quickly.

                      With the SS probe, its hard to tell how much of a lag there is, showing on the display.

                      The other one available from beanbay, without the stainless bit, is supposed to faster anyway.

                      Comment


                      • #12
                        Erics thermocouple adaptor with CS meter & TC?

                        Ah..... someone has already come up with the answer.........

                        Just came across this:

                        http://users.rcn.com/erics/Adaptor06.pdf

                        Looks great, but dont know if it could be used with the meter and probe from beanbay (?)

                        The article talks about waiting almost 1.5mins after a cooling flush, for the group head temp to stabilise again, due to heat being drawn out of the group head from reverse thermosyphon action.

                        On his E61 HX machine, at about 83 secs (after the flush) the group head temp starts to rise again and this is the point to start the shot.

                        Price seems to be USD$49 + $35 for express shipping.

                        Comment


                        • #13
                          Re: M27 dead band and boiler pressure setting


                          There may be a new model out now as this is the November  2007 model

                          Digital Thermometer & Adaptor for E-61 Groupheads (see PDF)

                          KK

                          Comment


                          • #14
                            Re: Erics thermocouple adaptor with CS meter & TC?

                            Thanks KK, yes thats from the same guy.

                            On the M27, the hex bolt for access is on the underside of the group head, and thats why I wanted to use the CS meter & temp probe.  Eg the face of a thermometer would be pointing down...    And it would be nice capture a graph via the USB link.

                            I think a different TC for use with the snobs meter might be needed though to fit the adaptor (?)

                            Comment


                            • #15
                              Re: M27 dead band and boiler pressure setting

                              What you need is this type of probe + Erics fitings



                              Then all that is required is a cable to connect it to the DMM



                              http://www.thermoworks.com/products/probe/tc_penetration.html

                              KK

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