# Classic: Shot cool at the bottom



## MikeHag (Mar 13, 2011)

Hi all. A few times with my Gaggia Classic I've found the last mouthful in the bottom of my shot glass to be a lot colder than the rest of it. I always run 3-4 oz of water through the brew-head just before attaching the portafilter, and always warm the glass. Could I just have forgotten to do one of these things, or could there be another cause?


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## MonkeyHarris (Dec 3, 2010)

What sort of glass are you using? In my experience glass doesn't seem to keep drinks hot for very long unless they're very thick or you've splashed out on some walled Pavinas (like me). My Pavinas don't require pre heating. Or it could just be you're savouring the shot too long









Edit: don't forget to let the boiler reheat after your cooling flush. Not sure how long is required with a classic but my Silvia needs about 30seconds after the light goes out.


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## MikeHag (Mar 13, 2011)

No fancy double-walled glasses







Just standard Happy Donkey 2oz ones.










I was wondering if maybe there could be a small amount of water sitting between the boiler and the brew-head, maybe in the OPV? (Sorry if this is not possible - I'm still learning how the machine works.)

I've just been reading old posts on various forums, and there's some advice about running water a little water through the steam wand just before hitting the brew switch. Maybe that would flush out any colder water that might be in there. I'll experiment in the morning... 1:08am now. I'm becoming a little obsessed with this little silver devil!!


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## Glenn (Jun 14, 2008)

3-4oz is a lot for a flush, 2oz at most is all that's required

The boiler is only 10oz


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## MikeHag (Mar 13, 2011)

Thanks Glenn.

So I'm a little confused about the distinction between priming the pump and flushing the head. The manual says to prime the pump by running a full cup of water from the head. Am I right in thinking that priming refills the boiler with a cup-full (which in this case is about 10oz) of fresh water, and a short flush just transfers a little of the water from the boiler through the brew-head, to get the temperatures consistent just before extraction? (Starting to wish I had a PID as I'm never sure when to press the brew button.







)

Getting back to the cold bit at the bottom, I just tried again and think maybe I've solved the puzzle.

I think it's not at the bottom after all! As I sip it down the crema at the far side of the glass stays on the top and is the last thing swallowed. Being on the top, it's had a couple of minutes exposed to room temperature and has cooled. Sounds plausible anyway.


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## PaulN (Mar 10, 2011)

I think it partly could be those glasses the bottom are pretty thick and even though i fill mine as you do from the group head it nevers warms them as much as a kettle...

Your right about the priming, it suggests first thing in the morning to do it but i also give it a quick blast into a cup before every shot as it forces the boiler to reheat so im not waiting for the light to go off then back on.

Cheers

PaulN


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## Glenn (Jun 14, 2008)

MikeHag said:


> Am I right in thinking that priming refills the boiler with a cup-full (which in this case is about 10oz) of fresh water, and a short flush just transfers a little of the water from the boiler through the brew-head


Pretty much

The prime ensures the boiler is full

The flush clears the showerscreen and removes water from the boiler

I personally think too much emphasis is placed on surfing. Most tests I have conducted have found the grouphead temp to be within 3c - within an acceptable brewing temperature range

If people have fiddled with their machine thermostats or made other modifications this will vary the temperature stability

Each machine is different

There are small affects for each shot, but not enough to destroy an espresso


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