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Minimum Warmup Time?

Posted: Mon Nov 12, 2012 10:30 pm
by Endo
Typically I use a minimum warmup of 30 minutes. I think I can get this down to 15 or perhaps even 10 minutes using some tricks I learned on my Cremina.

If anybody is interested, let me know and I'll do some comparison tests using my new datalogger.

Re: Minimum Warmup Time?

Posted: Tue Nov 13, 2012 12:09 am
by Johnlyn
I'm interested to hear about your warm up tricks.

Also, do you have the steam boiler going right away or do you switch it on about 15 mins before you may get into milk drinks?

Cheers

Re: Minimum Warmup Time?

Posted: Tue Nov 13, 2012 11:11 am
by richardcoffee
my wife turns on the Mini 1 hour before I get up. Then I turn on the steam boiler 5 minutes before I make our lattes. That's in the morning. In the afternoon when I want a latte, I'll follow the same course. If I need less time for the brew boiler I'd love to know it. Maybe I can spare myself burning up my wiring as I've read others have on their steam boiler.

Re: Minimum Warmup Time?

Posted: Tue Nov 13, 2012 2:43 pm
by Johnlyn
richardcoffee wrote:my wife turns on the Mini 1 hour before I get up. Then I turn on the steam boiler 5 minutes before I make our lattes.
5 minutes for the steam boiler eh! That's good news... Is it full power after 5 min or do you find it gets more powerful if you wait longer?

I am patiently waiting for my mini to arrive and I really like the ability to turn the steam boiler off until I need it.

Re: Minimum Warmup Time?

Posted: Tue Nov 13, 2012 4:33 pm
by richardcoffee
I get plenty of steam in 5 minutes. It was a pleasant surprise for me too. I don't know that it gets more powerful as time goes by. It is, in effect, up to steam.

Re: Minimum Warmup Time?

Posted: Tue Nov 13, 2012 5:08 pm
by Johnlyn
That's awesome! I like that!!

Re: Minimum Warmup Time?

Posted: Mon Nov 19, 2012 12:27 pm
by caf4brains
I'm also intrigued by a shorter warm-up routine!

Re: Minimum Warmup Time?

Posted: Sat Nov 24, 2012 9:55 pm
by Endo
OK. Here we go....

This is my setup: Amprobe Datalogger with thermocouple on grouphead. Dowloaded to laptop (not shown) running Artisan roasting software.
Temp Logging Setup
Temp Logging Setup
IMG_0325 (400x299).jpg (46.6 KiB) Viewed 25681 times

Re: Minimum Warmup Time?

Posted: Sat Nov 24, 2012 10:13 pm
by Endo
First a typical warmup.

My temp is the red line (ET) and my Rate of Rise (ROR) is shown in orange.

You can see the temperature rises quickly with the ROR peaking at almost 10 deg C/min just as the heater turns off the first time at 4:30 minutes, when the water hits the 94C setting. At this point, the heater starts cycling on and off and the ROR drops off.

After about 30 minutes, the grouphead temp is stabilized at around 84 C. This is what I would consider the minimum warmup time. But it's still too cool to pull a shot. I pull 2 warming flushes of 2oz each about 30 seconds apart to "warm the cold nose" and bring the grouphead up to 88C. This is about the maximum temp I can heat the grouphead. At this point I pull a 35 sec shot, and the temperature hovers around 87 C the whole time. (Funny enough, 87C is EXACTLY the same value I read on my Cremina grouphead at the start of shots, so it's a good indicator I'm getting 94C in the cup).

One thing to watch out for. Notice how the temp of the grouphead drops after the shot. After about 10 minutes, the grouphead is back to 85C or so and would require another couple of warming flushes if I was to take another shot.

You can now see the variables at play and how it works as a system (PID alone and 1 deg F accuracy means nothing). You can also see how a grouphead charge heater would probably have been a much better upgrade than adding a PID.

Next post will be with warming flushes starting at the 5 minute mark rather than at 30 min. (This is what I do to get my Cremina up to temp quickly). It will keep the ROR higher for much longer and I bet the warmup period can be cut in half at least....but how much water will it take I wonder??
Typical Warmup
Typical Warmup
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Re: Minimum Warmup Time?

Posted: Sun Nov 25, 2012 8:09 am
by slo
Thank you for posting this graph Endo.

As you suggest, running water while the heater is on will speed up the group head warm-up of the group head and using the blind (backflush) basket and leaving the hot water in contact with the group head for a while at every shot (you must empty the basket before every shot) will also speed up the process a lot.
Endo wrote:(Funny enough, 87C is EXACTLY the same value I read on my Cremina grouphead at the start of shots, so it's a good indicator I'm getting 94C in the cup).
Far from me to question the adequacy of the Cremina but how is the 87°C an indication that you will get 94°C in the cup?

Beside it is temperature of the water in the basket that is important not in the cup! Water should be at 93°C (if you ask me but you are not) while being in contact with the coffee. Not in the cup. I am sure that you know that but I am posting so that everyone is on the same wave length (or close!).

Re: Minimum Warmup Time?

Posted: Sun Nov 25, 2012 12:08 pm
by LDT
Endo, How about putting your other thermocouple in the cup and read the temp as you pull the shot? Your setup should be able to do that.

Re: Minimum Warmup Time?

Posted: Sun Nov 25, 2012 12:34 pm
by chas
I haven't proved this for myself, but I seem to remember reading that even if the temp coming out of the group is 94C and the PF has no "cold nose", the coffee temp is expected to be ~68C by the time it hits the cup.

Re: Minimum Warmup Time?

Posted: Sun Nov 25, 2012 4:43 pm
by MonkeyK
Endo wrote: After about 30 minutes, the grouphead temp is stabilized at around 84 C. This is what I would consider the minimum warmup time.
Your graph looks like the grouphead is still warming, but just at a very slow rate. How hot is it at an hour? Or if you leave it on all day?

Also, how is your thermocouple attached to the grouphead?

Re: Minimum Warmup Time?

Posted: Mon Nov 26, 2012 8:09 am
by Endo
LDT wrote:Endo, How about putting your other thermocouple in the cup and read the temp as you pull the shot? Your setup should be able to do that.
I am measuring warmup time at the grouphead using a thermocouple. You can't do this by measuring the shot temp or cup temp. I've done that many times before using my Scace so you can refer to those older posts if you are interested.

My thermocouple is stuck to the grouphead using aluminum tape. I find this provides a very accurate reading.

I know from experience that a 94C as a setting means 94C on my Scace which means 88C on the grouphead which means 68C in the cup. The thing that surprised me a little was how similar this formula was between very different machines like my S1 and Cremina.

Re: Minimum Warmup Time?

Posted: Mon Nov 26, 2012 9:26 pm
by Endo
Here's the latest test showing the "quick 10 min warmup". For anyone who wants to try it, here's how it goes:

1. Start first with the normal 5 minute warmup.
2. When the you hit your temperature set point at say 94C and all leds are lit, do your first 2 oz warming shot.
3. Wait for the lights to turn off then come back on indicating you're back to the set temperature. (The first time takes about 50 seconds and will get progressively shorter each warming shot).
4. Repeat steps 2 and 3 for 5 more times (6 warming shots of 2 oz total).

By the 6th warming shot the grouphead will be warmed to the same temperature as if you warmed for 1 hour and then pulled 2 normal warming shots (88C grouphead temp).
Quick 10 Minute Warmup
Quick 10 Minute Warmup
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Re: Minimum Warmup Time?

Posted: Mon Dec 03, 2012 1:06 pm
by caf4brains
Thank you Endo - I'll give that a try to see how it compares to my usual routine of approx 30 minute conventional warm-up and two warming flushes.

Re: Minimum Warmup Time?

Posted: Fri Jun 26, 2020 1:19 am
by Tokio
I thought 5 minutes is enough for steam being ready?