jamesw Senior Member Joined: 19 Dec 2001 Posts: 48 Location: North Carolina Expertise: I love coffee
Espresso: Silvia w/ PID of course. Grinder: La Cimbali Jr. Vac Pot: -- Drip: Braun Roaster: none
Posted Fri Dec 8, 2006, 7:21pm Subject: Re: Isomac Millenium First Look
"It won't change the operating characteristics of the HX but . . . "
Well actually yes it can. One can LOWER the boiler temp so that you have -- in effect -- a SINGLE BOILER MACHINE. With the temp. optimized for what SHOULD be the 'prime directive' making espresso -- not steam.
Posted Fri Dec 8, 2006, 9:13pm Subject: Re: Isomac Millenium First Look
jamesw Said:
One can LOWER the boiler temp so that you have -- in effect -- a SINGLE BOILER MACHINE. With the temp. optimized for what SHOULD be the 'prime directive' making espresso -- not steam.
That's just not true. The HX will never function like a single boiler because it doesn't use boiler water for brewing.
Water is heated "on the fly" as it travels from the source to the brew group so by design the boiler NEEDS to be hotter than brewing temperature. No matter what you will still need to run purge flushes before brewing.
If you have something to say then why not say it? I'm not going to argue with you, but we should take this opportunity to inform others who may not understand.
What you're talking about is using what I'd call the PURGE water to make the shot. That means you let the water in the HX tube stabilize in the boiler and use THAT fluid for your shot. You don't need a PID to do that, you can just set your p-stat at 0.1-0.35 bar (or therabouts) so that the water in the HX and in the boiler are close to brewing temperature.
The obvious disadvantage is that you effectively reduce your brew-boiler size to the volume of the HX tube (4-6 ounces in most home machines). That means you can only make one shot, maybe 2; and then the "new" water from reservoir starts coming in and lowering the intra-shot temperature profile so you would then need to allow sufficient time for the boiler to fully recover and bring the HX tube contents back to the steady state temp (maybe 2-3 minutes would be enough for most home HX machines).
This does NOT change the operating characteristic of the machine. That would require a physical change like re-plumbing the brew path to use boiler water for brewing. It doesn't make sense for those home users who want to make more than a shot or two in sucession (or those who want to steam milk) but it's fine if you usually brew alone and only make 1-2 shots
jamesw Senior Member Joined: 19 Dec 2001 Posts: 48 Location: North Carolina Expertise: I love coffee
Espresso: Silvia w/ PID of course. Grinder: La Cimbali Jr. Vac Pot: -- Drip: Braun Roaster: none
Posted Sat Dec 9, 2006, 8:47am Subject: Re: Isomac Millenium First Look
" . . . . but it's fine if you usually brew alone and only make 1-2 shots"
and that is EXACTLY the usage pattern of MOST home users.
Using a 'pid' controller eliminates the obsolete pstat, eliminates noise, drift, sticking, and failure, affords instantaneous adjustment of temp/ press -- from the front panel, and delivers immediate accurate feedback to the user.
Adjusting a (usually inaccessible) pstat with a screwdriver is not a great option.
Quoting: " I purchased (off ebay) a Fluke thermometer so that I can dial-in brew temperature. Wow with the PID I can consistently hit that 203 degree sweet spot endlessly. "
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