i understand there are many threads and discussions about managing the temperature on HX machines. I have spent countless hours reading but I am afraid so much information has me more confused.

I recently installed Eric's thermometer adapter on my plumbed Rocket Cellini Evoluzione. The readings let me know I had to change my flush routine. I tried every method I have read but still wasn't getting consistent results and I am somewhat of a perfectionist so that just won't do.

After hours of testing I came up with my own temp managing method that I haven't seen anyone else use so I wonder if there is a reason to that...

I understand the temp shown on the thermometer is ~4 degrees higher than the actual temperature hitting the puck. I figure 202 is my ideal temp at the puck so my goal is to hit 206 reading on the thermometer during the shot extraction.

First off these are my Cellini's vitals
Pstat: 1.1 bar max
Group pressure: 9 bars
Water coming into the machine: 56 degrees F

I let my machine warm up for at least 45 minutes. Flush until I don't hear the flash boil, let it sit for another two minutes, then I am ready for brewing.

Now here is my method.

1) I take note of the temp reading on the thermometer, this lets me know how long to flush.
198= 1 sec
199= 2 sec
200= 3 sec
201= 4 sec
202= 5 sec

2) After finishing the flush I wait 35-40 seconds, during which I grind, dose, and tamp.

3) After the 35-40 seconds (regardless of what the thermometer reads) I begin the extraction, the readout immediately shows 206 at the top of the shot, then drops to about 204 by the end.

4) I let the machine sit for at least 2 minutes.

5) I now take note of the temp readout again and do step 1 for my next shot.

and that's it, i base my flush on the initial group temp readout. i don't measure how much water i flush, i don't stop it at a certain temperature. simply flush for the amount of seconds to the corresponding temp reading. Following this method i get the same temp reading each and every time.

now is this a good method or is there something i should be looking at?

Hello, I have the same machine as you. Well actually the Giotto Evo, but same internals. I have also installed an Erics therm and he has spent a good amount of time helping me get good results. Now correct me if I'm wrong eric but given the restrictor in the machine, Alvin's 30-45 sec wait is not really a true flush and wait, but rather a slightly longer flush and go. With this in mind, the +4 degree rule may not be quite accurate. The general idea is that the therm reads ~4 degrees ABOVE actual group head temp when you employ a flush and wait technique. However, if you are using a flush and go technique then the therm is reading ~4 degrees BELOW what the group heads is actually at. So given the reduced rebound speed the restrictor creates, your 30-45 seconds is more like a very minimal flush and wait and probably closer to a flush and go. Now good results are good results so all this may mean nothing except that you may actually be brewing hotter than you think.

Alvin.A wrote:... Water coming into the machine: 56 degrees F ...

The inlet water temperature may rise considerably in the summer and the group heat loss characteristics may change depending on the air conditioning in your location so don't expect the winter routine to last year round.

the point you brought up Nixter is what i have been wondering. However the good old flush and wait gives me very inconsistent temp readings. highest reading being 202F, which would translate to 198 at the puck, and they all taste sour. (i could never see a water dance on my machine so i stop the flush when the audible 'SHHH' subsides)

could it be that i need to wait more time after the flush since the water coming into the machine is so cold?

i guess i wont know what my method is producing at the puck unless someone lets me borrow their Scace contraption.

Am I correct that if I flush to 185 degrees F and allow grouphead to rebound to 198 degrees F, that once I pull the shot, I can expect the temperature will momentarily climb to as high as 212 degrees and thereafter slowly start to fall? How quickly should the thermometer come down to 202 degrees F? Where should the reading be at the end of a 25 second pull?

Eric:

I am using the Andreja Premium. I find when I flush and wait, going down to 185 and climbing up to 198, when I pull the shot, the temp spikes to 211-212 and then back down. Last night after I posted, I made some decaf lattes for myself and my wife. I pulled the first shot at 197 and it spiked to 209 and the second at 196 and it spiked at 208. Your response seems to suggest that if I pull at 198, the temperature should stabilize more or less at 202 across most of the 25 second pull. That is definitely not happenening here. I will try to pay better attention this morning, but it has not been my experience that the temperature "settles" at any particular number. Am I looking for an average here or is there something wrong on this end?

OK:
Pulled at 197. Temp shot to 210 momentarily then quickly lowered to 205 through the shot and even climbed to 205.5 when I killed the shot. I didn't come off the grind enough from the decaf last night so pour went long, probably 32 seconds but still enjoying what is in the cup. I have lowered the boiler pressure to 1.1. The brew pressure is probably about 9.75.