I was asleep at the wheel, sorry about the delay Justin. The titans have been taking most of my time.
jgriff wrote:I have a few questions for you guys:
1) I know this is probably coming, but it would be helpful to have readings from a thermofilter to compare to Dave's graphs using the TC adaptor so we can see what the results in the cup are like. You didn't say whether you tried the shots from your "testing" or how they were.
I had mentioned earlier that I was holding off doing the graphs because I was waiting for a Scace II thermofilter. Unfortunately they are in short supply so I decided to press on with what I had. When it arrives I plan on running one or two more graphs with both the thermofilter and E61 adapter. The shots I pulled were with old garbage beans. Leftovers from a pound of this and a pound of that so they were not fit to drink. I simply ground fine enough to get a properly timed shot and went at it.
2) Have you noticed whether it takes longer for the group to get to stabilize at operating temperature after a shot or series of shots or when first starting up? (Actually, this brings up another question I've had which is what "normal operating temperature" for an E61/HX design should be if it's being used as it was designed and not overheated, but we can save that for later.
) I wonder what effect the thermosyphon restrictor has on this. It seems like the GH would cool off after a shot or several shots and it might take longer to get back to operating temperature with the restrictor. Does this make sense?
The first part of the question: It takes longer to stabilize in the heat up phase. The machine needs a good 45 minutes to heat, an hour is even better. Shot to shot, I was able to outpace the machines recovery ability. If everything is ready, I can bang out shots pretty quickly. I would guess around 100 seconds from shot to shot. After the third shot it did need a few moments to recover. If you pace is more like a double every 3-4 minutes, I believe the machine would keep pace until you ran out of coffee.
My intra shot flushes were all but non existent. I would give the machine a quick 3-4 second flush just to clean off the shower screen while I was tamping. Then lock and go. If you are making milk based drinks, pull two doubles, froth your milk and serve them, then pull the next two, milk etc. At that pace it keeps up just fine. I ran the machine at work for a while. I could knock out 6 drinks back to back using that technique.
Second part of question two, the normal operating temperature of an E61 group. Ideally, that would be the brew temperature you wanted, or slightly higher. On my Isomac, which does not have a thermosyphon flow restrictor, the idle group will heat up to the 212F range. That requires a very long cooling flush before I pull my first shot. As long as your brew water is the correct temperature, the group should maintain close to that temperature. If the brew water is too cold then the water will leach heat from the group until equilibrium is reached. Same holds true if your water is too hot. The group will leach heat from the water in an attempt to equalize.
3) Any idea whether having the patent on the original E61 design means the VBM has the same, larger chamber #3 in the GH design as discussed
here?
I'm just wondering how the design of this machine affects it's behavior and whether it is markedly different from other machines, like my Anita. Thanks for an interesting review and all the
hard work you guys do!
Justin
I don't know. I have not taken the group apart that far. I would have to ask a service tech for that one. What I can say is that the group preinfusion timing and pressure profile is common.
I can tell you that Dan (HB) has some interesting things planned for that grouphead he got from 1st-Line. So that question may get answered in the future.
RandyG!).
