What the ... Is the reason....

Vincent Ouellette

Hi,

I have observed a curious phenomenon that I just cannot explain... It is not really a problem just a curiosity...

My set-up is a L-1 and a Mahlkönig k-30 and I always pull my shots the same way...

I use around 16gr of coffee in my 18gr VST, I tamp always the same way. I do a short flush before my first shot and after each one to clean the shower screen.

I have a timer to turn on the machine at 4h30 in the morning and I usually wake-up between 5 and 6. The shots are always perfect and constant.

BUT... This is what I do not understand...

If I come back home early enough, I like to gratify myself with a nice coffee, but if I pull a shot after about 10 minutes using the exact same technique, the coffee will piss during pi...

WHY?????

Is it because the group and pf are not warm enough... I just do not understand... The second shot will be perfect.. I know I just have to wait a few more minutes and do not experience the same thing, but this does not explain why it does that.

Fell free to enlight me...

Vincent

Frans Goddijn

You flush away the first 10g of grinds to make sure you have fresh grinds, no old grinds from the retention of the K30?

Vincent Ouellette

Well, It does not explain the phenomenon since it will not do that in the morning even if there is a few grams of coffee in the grinders that sat there for 18 hours.... When I come back home the leftover will have been ther only for a few hours...

Reiss Gunson

hi vincent
thanks for posting - its good to see posts from owners that don't post very often
are you starting your machine from cold in the evening? (or has it been on all day whilst you have been at work?)
if you are starting from cold and pulling a shot after just 10 minutes, then yes, you have answered your own question - the system is too cold - adjust your timer for the machine to come on for a second interval - the digital timers all seem to offer multiple on-off sequences for each day
kind regards
reiss.

Unknown

Vincent Ouellette post=10917 wrote:
If I come back home early enough, I like to gratify myself with a nice coffee, but if I pull a shot after about 10 minutes using the exact same technique, the coffee will piss during pi...

WHY?????

Is it because the group and pf are not warm enough... I just do not understand... The second shot will be perfect.. I know I just have to wait a few more minutes and do not experience the same thing, but this does not explain why it does that.

Hi Vincent,

Nice question!

Hypothesis: the coffee particles don't take up enough water, don't swell enough to close all the gaps between them, just because the water is too cold.

Experiment: use two paper coffee filters; put in each the same amount and same grind of coffee; to 1 filter add a cup of lukewarm water, to the other the same amount of boiling water;

Observation?
Conclusion?

(My guess would be that the 'cold' water will run through quicker and not extract much.)
Hmmm, maybe I'll try it out tomorrow myself...... :-)

M.

Vincent Ouellette

Thanks guys,

The cold water is probably a factor here... I guess that starting from cold at 5pm and pulling a shot at 5h10 is a very short heating time even if the heater is off after bringing the pressure to 1.3 bars. The thermosyphon is probably not runninng yet and the water in the group would still be colder even after a short flush...

It is great to think that this machine is so stable that you always know if something is just a bit odd...

I had to fight a few days to adjust the grinder's setting ans the tamping to use the 18gr VST but I do believe I get a slightly better coffee with that set-up.... A bit more volume and faster flow with nice center cone.

I love my mornings!!!!