Isomac Millenium V2 advice on operation
I have just managed to upgrade from a heavily modified Gaggia Classic to a second hand Isomac Millenium V2! An exciting moment and one not without trepidation...
After finally kick-starting the pump into action it appears to be all working well, except for the green 'ready' light being dead, which I can live without as it only turns on when a red one turns off anyhow.
At some stage the steam and water arm springs had became mangled and wrecked, and removing the remnants makes the arms go floppy, so they are both jerry-rigged with an extra Oring and now working nicely.
One slight concern is that the boiler pressure was fluctuating between 1.5 to 1.7 Bar. It was comforting to see a normal looking 0.2 dead band, but my understanding is this is way too high. I have adjusted the pressurestat to swing from 1.1 to 1.35 (reaching 1.45 due to the delay) and the dead band has therefor become a little larger. Is this an indicator the pressure stat is on the way out?
At the moment I'm going through the cleaning and setup and have backflushed extensively to get it clean, scrubbed the shower screen, replaced the fossilised group seal with a cafelat silicone one, and dismantled and lubed the cam in the group (checking all the seals too). I think had covered everything I need to check, but I still need to descale as the mushroom had chunks of scale on it and loss of some chrome.
Pulling some shots was a little underwhelming. I'm using a Mazzer SJ grinder and I am confident my distribution is good, with the pours looking good, but I considered the shots burnt. I have since realised that an extensive cooling flush is needed to cool the group before pulling. This seems to be a common thing in the UK but not discussed much on the forum here. With this being an Australian machine from about 2010, would it be normal to need the gicleur changed to get everything balanced, or should it be all set up and no flush should be needed?
Any advice on boiler pressure, etc would be greatful!
Hi, fellow Millenium user here.
boiler pressure :
mine is set at 1.1bar and a 0.2- 0.3 bar "dead band" range is not uncommon and not a problem in my experience. But it is easy enough to swap out he pressurestat if you believe it will give peace of mind . My experience is they tend to fail after 4-5 years use anyway, so keeping a spare is sensible.
Brew temperature :-
If you machine was a genuine Au supplied unit, it should have had the Hx circuit "tuned" to suit local preferences, ie minimal flush needed before brewing. But many of these machines seem to have missed out on that "tune up" and will need a cooling flush to get the best out of them.
However, it is not the Gicleur that is changed, but restrictors in the Hx circuit (inside the piping inside the machine) to control the recirculating flow around the group head. If you are feeling lucky, you can attempt that yourself using restrictors purchaced or homemade, but its a fiddly job with lots of trial and error, dissassembly/ reassembly, testing etc etc, to get the ideal recirc rate. if you can find a helpful tech to sell you the correct restrictors , it will be much simpler.
Personally i still use a quick (1-2 sec) flush before loading the PF to the group head, but that is more of a habit from barista training on commercial machines to ensure a clean dispersion screen.
Good luck with your new machine, im sure it will work well for you. Mine was a grungy, scale blocked dead duck when i got it, but simple cleaning, a descale, basic maintenance, and it has worked flawlessly for the last 8 years of daily use. (Other than a couple of pressurestat replacements !)
Thanks very much for that advice! Further trawling of information here was leading me to reduce the pressure further, so with your recommendation I will aim for 1.1 max pressure and hope the dead band doesn't drop it past 0.8. From there, I will see how the cooling flush goes. I'm just really out of the habit of doing it with the Gaggia so need to adjust my routine.
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