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Is It Worth Putting A PID On A Rocket Giotto?

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  • #16
    Originally posted by Bames View Post
    Are you trying to achieve the ability to change brew temp? Get a DB.
    Yeah that's what I was thinking, I am pretty ignorant, I actually thought the Giotto IS a DB ha, because you can steam and extract at the same time! Sooo I'll just have to learn to use what I've got as I'm not buying another machine after spending all this dosh on a Rocket! I just wanted to tinker, but if there's no point to it I'll just have to put another turbo on my Golf or something :P

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    • #17
      Originally posted by Bames View Post
      Ok seriously. Again. A PID will reduce the fluctuations in STEAM boiler temp. It will do very little if anything to your shot temp and stability.

      Are you trying to achieve the ability to change brew temp? Get a DB. Trying to get a consistent and repeatable shot temp variance using steam boiler temp is not really possible.
      are you suggesting that moving the steam boiler temp up 5 or 10 degrees will not have any proportional effect on the group temp or brew temp. .?
      Isnt that why you use the scace device ,..to check and adjust pressure and/or temperature ?
      A PID is a lot cheaper than buying a dual boiler.
      .....if you want to do that sort of thing !

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      • #18
        Of course moving the boiler temp up by 5 or 10 degrees will change the brew temp. But...
        Can the boiler safely handle a 10 degree increase? Probably not. 1-2 degrees C will be around 0.1ish boiler pressure.
        Will that change have a direct, linear and measurable difference to brew temp? Unlikely. 1 degree C steam temp won't equal 1 degree C brew temp. What will it equate to? Who knows. Will 1 degree jumps in boiler temp eg 120 and 121, and 121 and 122 make the same proportional jump in brew temp? Very unlikely.
        HXs just don't work that way. If you want the kind of tweakability, you need a DB. so back to the question of what do you want to achieve?

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        • #19
          Agreed. If you want to play the brew temp game, buy a dual boiler or PID a single boiler. Attempting it with a HX is at the expense either of steam pressure and quality or the reintroduction of a cooling flush.

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          • #20
            +1 Agreed. But I have to re-post what my Giotto V3 wanna paint the picture to adjust boiler temp, and then you will see the SCASE measured brew temp from the group head. when you change boiler temp from 118C to 122C degree, you will have accordingly brew water temp from 90.4C to 96.08C degree. believe it or not? still, not my concern Click image for larger version

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            • #21
              Thanks Ibiza - that's a good resource.

              But don't think for a second you can chuck a PID on a ECM Giotto - or even an V1 or V2 model Rocket Giotto and get the same brew temp for boiler temp as that scale indicates due to minor tweaks in thermosyphon design over the time.

              It actually goes further than that. This is the spec coming from the Rocket factory in Italy. When machines arrive here, local retailers usually (if they're worth buying from) bench test and calibrate so that brew temp is (a) whatever temp they set it at, and (b) shot stable. So it may well even be the case that brand new V3 Giottos don't match that graph due to tweakings by the Aus retailer.

              So, as I've been saying all along, while yes it is true that changing the steam boiler will change the brew temp, you're running around at night, in a huge dark room, with no windows, wearing a blind fold, trying to play darts.

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              • #22
                Originally posted by Bames View Post
                while yes it is true that changing the steam boiler will change the brew temp, you're running around at night, in a huge dark room, with no windows, wearing a blind fold, trying to play darts.
                well, I doubt few know exactly the temp the need for any specific bean anyway ...but you could use a brew head thermometer if you think that knowing the actual temp is any benefit.
                So, not much different to a DB at the end of the day !

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                • #23
                  Originally posted by Gavisconi007 View Post
                  The Giotto (without PID) is also very stable. I have never done any flushing that some suggest is necessary and the first shot is as good as the second is as good as the third, and this is every time, not hit and miss. Maybe I just got lucky with mine?
                  Nah mate, they're all like that in Australia, it's the 110Volt ones you gotta watch

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                  • #24
                    Originally posted by Bames View Post
                    Thanks Ibiza - that's a good resource.

                    But don't think for a second you can chuck a PID on a ECM Giotto - or even an V1 or V2 model Rocket Giotto and get the same brew temp for boiler temp as that scale indicates due to minor tweaks in thermosyphon design over the time.
                    what's the difference between an ECM Giotto (what I've got) and a V1 Rocket Giotto? Google isn't much help on that question

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                    • #25
                      Google "ECM Giotto inside" and "rocket Giotto inside" and take a look at the internals. You'll see a longer pipe between the top of the HX and the e61 inlet on the rocket than the ECM.
                      Also, control board is different = more reliable
                      Pstat was upgraded (I think)
                      Different pressure gauge
                      Different OPV
                      Other cosmetic like drip tray etc
                      Don't think there's much more?

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                      • #26
                        Originally posted by Bames View Post
                        Google "ECM Giotto inside" and "rocket Giotto inside" and take a look at the internals. You'll see a longer pipe between the top of the HX and the e61 inlet on the rocket than the ECM.
                        Also, control board is different = more reliable
                        Pstat was upgraded (I think)
                        Different pressure gauge
                        Different OPV
                        Other cosmetic like drip tray etc
                        Don't think there's much more?
                        Hmm, I prefer the ecm style drip tray. The newer rocket one looks just like my cheap old nemox machine So if I get replacement parts now, like a control board, is it from the rocket model?

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                        • #27
                          Just like to point out one thing after doing a lot of research and time spent calibrating my own PID'd DB machine,
                          I can pull 60-90ml through my double shots with <1'c temp change at the bottom of the basket., (the temp does initially drop a few degrees as the puck soaks up some heat, due to not keeping ground beans at 93')

                          BUT the PID shows 3-6 degree drop in boiler temps (due to cold water inflow) and proximity of the inlet pipe to the boiler temp probe.

                          So as pointed out above, Boiler temp does not always directly relate to water temp through the puck.

                          I think a few kg of brass and the correct amount of water syphoning through it will do a highly effective job of maintaining stable temps.
                          moreso than a $30 piece of chinese circuitry..

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                          • #28
                            Originally posted by Robbks View Post
                            I think a few kg of brass will do a highly effective job of maintaining stable temps.
                            True. I have an E61 DB and my understanding is that the brew boiler is actually set to maintain temperature marginally above desired brew temperature because the group head is exposed and will therefore always itself be below the temperature of the water that is thermosyphoned from the brew boiler.

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                            • #29
                              Originally posted by Dragunov21 View Post
                              The average temperature of the boiler, which is doing it's thing fast enough that the group temperature should not fluctuate.
                              It will affect the water temp discharging from the HX piping, but I'd question how significant that fluctuation is at the shower screen..
                              The fluctuations between pstat firings, or a change in the boiler set point?

                              with the former, very little (the group head is an inductor); with the latter, a lot.

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                              • #30
                                Originally posted by Hildy View Post
                                The fluctuations between pstat firings, or a change in the boiler set point?

                                with the former, very little (the group head is an inductor); with the latter, a lot.
                                The former.

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