Markarian Senior Member Joined: 27 Jun 2012 Posts: 474 Location: Seattle Area Expertise: I love coffee
Espresso: Modded Nuova Simonelli Oscar Grinder: Vario-W, Mazzer Super Jolly Drip: Moka, Aeropress, Melitta 102 Roaster: Wear-Ever Popcorn Pumper
Posted Mon Mar 4, 2013, 1:21am Subject: How does temperature affect shot flow?
Another big, vague question but I need some insight. Recently, a certain South Park character from Germany noticed that I never kept my PF locked on the group when I'm not using the machine. Yesterday, I started doing this since I guess it's the thing to do (why do I need the PF hot?) but I've noticed it's acting like a huge heat sink and making my flush routine much different. I'm getting a smoother flow out of the group, but I also noticed that a shot I pulled that was same grind, same coffee as one I had pulled earlier in the day was completely choked! I may have messed up my tamp, but it got me thinking and that I have noticed that it really seems like brew temp will effect the extraction flow/speed/cone of the coffee but someone else on here who I can't remember said it doesn't. I'm kind of confused now at this point and hoping to better understand this and how it relates to the "water dance." Also, my group has been modified recently (not enough thanks to Plindy) with the Musica's flow restricters for better temperature regulation. I've had no issues with doing flushes until now, doing the whole PF thing.
Of course the cold PF acts like a heat sink at first. That's why you need to heat up your machine (with the PF locked in the group) for 30 to 45 minutes in order to reach thermostability.
*** "This drink of the Satan is so delicious that it would be a shame to leave it to the infidels." (Pope Clement VIII on coffee)
Markarian Senior Member Joined: 27 Jun 2012 Posts: 474 Location: Seattle Area Expertise: I love coffee
Espresso: Modded Nuova Simonelli Oscar Grinder: Vario-W, Mazzer Super Jolly Drip: Moka, Aeropress, Melitta 102 Roaster: Wear-Ever Popcorn Pumper
Posted Mon Mar 4, 2013, 1:52pm Subject: Re: How does temperature affect shot flow?
Definitely the one in question :)
I do let my machine heat up each morning an hour and fifteen minutes before I wake. Now that I have a vacuum breaker (Thanks Plindy!), I put the Oscar on a timer and it's ready to go in the mornings. But the water seems much cooler than usual on the initial flush because of the PF now, and I'm worried that, since we installed the flow restricters, that the group may not be getting hot enough now that the PF is sitting in there. Is this actually a potential problem?
I also couldn't understand why keeping the PF hot would be worth it if by my next shot the PF would have been run under warm (but much colder than the group) water in the sink to rinse away the grinds from the previous shot.
diggi Senior Member Joined: 28 Nov 2011 Posts: 382 Location: Halifax, NS Expertise: I love coffee
Espresso: Spaz vivaldi S1 V2 Grinder: B Vario, OE LIDO Drip: Chemex, Espro Press,... Roaster: Poppery I
Posted Mon Mar 4, 2013, 2:04pm Subject: Re: How does temperature affect shot flow?
Markarian Said:
I also couldn't understand why keeping the PF hot would be worth it if by my next shot the PF would have been run under warm (but much colder than the group) water in the sink to rinse away the grinds from the previous shot.
Because there is a significant thermal mass in the pf. When the whole thing is piping hot, a simple flush with warm water will do little to affect that (though I myself only flush under water from the group; wiping the basket with either a paper towel or microfiber cloth, depending on how messy the basket is after the puck is dumped). I would think the pf would take even more than one shot to get up to temp if it was sitting out of the group (especially if rinsed between shots).
Basically, the pf is a heat sink from the group until it comes up to temp. Then it adds to the thermal mass, adding to temp stability of the group.
Markarian Senior Member Joined: 27 Jun 2012 Posts: 474 Location: Seattle Area Expertise: I love coffee
Espresso: Modded Nuova Simonelli Oscar Grinder: Vario-W, Mazzer Super Jolly Drip: Moka, Aeropress, Melitta 102 Roaster: Wear-Ever Popcorn Pumper
Posted Tue Mar 5, 2013, 2:31am Subject: Re: How does temperature affect shot flow?
Hey thanks, guys! I guess what's got me confused is now I'm noticing major grinder creep. A setting of 2N-O on my Vario used to be fine for the same coffee, and now it's completely choked and wants to be all the way down at 2R or 2S. This pretty much changed when I started letting my PF heat in the group, as Nobby suggested. Any idea what's going on with the puck?
germantownrob Senior Member Joined: 2 Dec 2007 Posts: 2,017 Location: Philadelphia Expertise: I love coffee
Espresso: Duetto 3, A Dead Oscar Grinder: Vario-W, Preciso w/Esatto,... Drip: Brazen Roaster: Diedrich IR-1, HT B
Posted Tue Mar 5, 2013, 4:39am Subject: Re: How does temperature affect shot flow?
Do you have two PF? Pull back to back shots, one with preheated PF and one not, of course this only works if you can pull two consecutive shots with the same PF.
I had a Vario motor wear out on my last Vario, the motor changed speed during a times grind and could deliver non consistent timed grinds. Baratza allowed me to trade in my Vario for a Vario-w. My first Vario had lots of problems, two of which was the calibration would slip and I needed to calibrate every week at least, also the adjustment levers would not hold position. Baratza will take care of your grinder if that is the problem.
A 2-4 micro grind change is not uncommon, two clicks is very common for me from one day to another as beans age and environmental changes with a hopper full of beans. Single dosing always added an element of chance on my opinion, micro grind setting for full hopper and single dose are different and I remember have to make adjustments daily to keep shot flow.
I believe you like to use a naked PF most of the time. The path of brew water does not touch a naked, a naked has less mass so will be much quicker to preheat and really all the preheat does is keep it from robbing heat from the group which you have recently modded to have less heat. A spouted PF has more mass and therefore can rob more heat from the group plus it will cool the shot when it flows over the bottom of the shot which does not effect extraction.
Markarian Senior Member Joined: 27 Jun 2012 Posts: 474 Location: Seattle Area Expertise: I love coffee
Espresso: Modded Nuova Simonelli Oscar Grinder: Vario-W, Mazzer Super Jolly Drip: Moka, Aeropress, Melitta 102 Roaster: Wear-Ever Popcorn Pumper
Posted Tue Mar 5, 2013, 5:32am Subject: Re: How does temperature affect shot flow?
I do have a few PFs, but only one naked, and only one 18g VST.
I'm doing an experiment and leaving the PF off the group once more to see if my grind settings will return to the neighborhood they were in the other day. I'm just stunned leaving the PF in would make the grind need to be 4 micro clicks away. I'm not worried about the grinder so much. I'm always in and out of Baratza since I'm only ten mins away and they're always happy to put up with my pickiness and work on my Vario-W for me. They've taken very good care of me, both with my old Virtuoso and now my Vario-W.
Is there a rough guess as to how many micro clicks equals a macro click? Cheers!
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