How low ambient room temperature affects grouphead / brew temperatures

Jack Blackmore

As the title suggests does anyone have any feedback on how room temperate correlates to brew temps?

I've got my L1 on a timer switch for my morning coffee however in the morning my kitchen is fairly cold, between 12 - 15 Celsius (53-59f) and was wondering how this will correlate to brew temps. Today is my first day of ownership so need some time to learn the ins and outs however the shots I pulled this morning were all under temp / sour.

I think I may have slightly stalled the thermosyphon last night when I was playing around as I did not do the short flush after each shot so I don't think the grouphead warmed up entirely but will be able to do more extensive testing tomorrow when I have more time (not while trying to get ready for work!)

I've seen posts elsewhere stating that the PSTAT of 1.2 is fine up to ambient temperatures of 25c however I can't find any details regarding the lower threshold.

Any feedback would be appreciated

Robert Hall

So, when you make espresso in the morning, the kitchen is that cold? You could always turn up the heat. You could always get a Scace device and check it out. I have one but my house is never that cold!,
Rob

Frans Goddijn

I have done a lot of temperature measurements, logging them using Artisan software. Still those exact graphs are not transferrable 1-on-1 to other machines, for instance because the probes used can be very different in response time and the exact location where they are stuck on the group does make a difference also. And a kitchen of 20ºC ambient temp measures different if a window is slightly open and airflow is going past the group, or if a kitchen starts out cold but is warmed up as people wake up and start the day.

Also, measurement of the group is relative as the probe is not just feeling the group but is also influenced by room temp, as the probe is not drilled deep into the group but hanging onto it, like a person climbing a building is not just feeling the warmth from the building but also the wind around it.

If you mainly use the machine in the early morning, having the timer switch it on 2 hours before you get up may be a good idea. If you taste the coffee and you feel it could be hotter, try a slightly higher boiler pressure.

The group is designed to cool down the hot water entering it so basically it's fine to be cooler than the inside of the machine, just not way too much. The brew group being so heavy helps to make it a robust system, as long as you remember to do the brief after-shot flush to ensure the thermosifon is enabled to do its job.

Frans Goddijn

Robert Hall post=12303 wrote: You could always get a Scace device and check it out.

I also have a Scace but I find it of limited usefulness and at best it's just a basic roundabout indication. If you use the device on a brew group that you are convinced is optimal, the values you get can be used to see if another yields similar results.

To get a more truthful indication of temperatures of actual brew happening inside a coffee puck, you need a probe inside the coffee puck. I have that device also. I requires careful dosing and tamping and checking that there is no channeling.

All temp values in a Scace (the plastic puck, the bunch of wires allowing a steady tiny high speed stream of hot water, the probe hanging over it) are dramatically different from actual coffee extractions.

Jack Blackmore

Are you the FransG from Home-Barista?! Assuming it is you I've read a fair few of your posts and was actually going through one this morning so I think some thanks are in order I really appreciate the time you've gone into logging and getting the data out there as it helped me diagnose an issues I had with my Rocket which I now think was exacerbated by my super cold kitchen :D Unfortunately kitchen temperature is probably the one variable I can't readily control, it's an converted building with massive sash windows, high ceilings, poorly insulated and tiny little electric radiators!

I think my issues this morning were mainly as a result of a stuck thermosyphon so I'll give it a good test tomorrow and if they're still coming out sour I'll up the pstat and warmup times and see how I get on. I'm hoping I shouldn't need to go above 1.3bar as milk steaming becomes a bit of a wrestle but is there an upper level I should definitely stop short of? I'm assuming that if I get much above 1.3 then I'm getting into the realms where I should be correcting it with technique rather than brute force.

Under normal circumstances with the machine fully warmed up what steps should I be following? So far all I've found is the comment on the quick flush after the shot but I've seen a few videos with people flicking on the steam quickly?

Also I've noticed that when I unlock the portafilter after the shot there's a slight 'pfft' that sounds like air being sucked in, I assume this is the thing that's causing the stall?

All issues aside even the most tepid, under extracted shots are already tasting better than some of the crap I pulled on my Rocket :D

Frans Goddijn

Jack Blackmore post=12306 wrote: Are you the FransG from Home-Barista?

Yes there was a time that I was very active there. Most of my coffee activities are logged on https://kostverlorenvaart.blogspot.nl

How long ahead of waking up do you have the timer switch on the machine now?

Steaming at higher boiler pressures can be easier if you use a steam tip with fewer holes, but generally it's all about practice and having enough milk in the jug. High power steam blasting out of 4 holes might not work on a dash of milk for just one cappuccino in a small jug ;-)

Jack Blackmore post=12306 wrote: is there an upper level I should definitely stop short of?

In my experience the over-pressure valve opens and warns you if you reach 1.5 bar but it would not be necessary to even go there I suspect.

If your kitchen is the issue then maybe move the L1 to a different corner of the home ;-)

The routines are well documented in videos, like the ones Trevor Watters made, or he and I together.

Jack Blackmore post=12306 wrote: So far all I've found is the comment on the quick flush after the shot but I've seen a few videos with people flicking on the steam quickly?

If you let out some steam you may notice the heater kicking in to warm up the boiler and this way you can ensure that you will release the lever at the optimal pre-infusion pressure. But I suspect that with the current high quality piston seals, that trick is less critical.

Jack Blackmore post=12306 wrote: Also I've noticed that when I unlock the portafilter after the shot there's a slight 'pfft' that sounds like air being sucked in, I assume this is the thing that's causing the stall?

I suspect that is just some residue of pressure above the puck. At that point the lever is up and the piston is securely closing off any connection with the thermosifon. The four inlet holes you saw before sliding the piston into the bore are by then guarded by the top two seals, the top one with its skirt open towards the holes, preventing water leaking upwards, the middle seal the other way around.

And the lowest seal is guarding against any pressure sneaking past its 'skirt' upwards. Otherwise, coffee could be sitting above the shower screen instead of in your cup ;-)

Enjoy the shots!!

Jack Blackmore

Thank you for all the information! We've just taken a cupboard off the wall to fit the L1 on the worktop so it's pretty much fixed to where it is! :D I'll report back once I've had a chance to test with a proper warmup tomorrow and see how it goes from there!

Reiss Gunson

https://londiniumespresso.com/blog/blog/631/important-londinium-pressure-stat-settings-at-various-ambient-temperatures

Jack Blackmore

why am I not surprised this already exists! I did a search of the forum but didn't think to look in the blog! Cheers Reiss

Matthew Hoffman

I've found that if the group is not sufficiently warmed-up for the first shot of the day, a flush or two will raise the temperature sufficiently. After the first shot, and subsequent flush, the group will retain plenty of heat throughout the day. You might consider attaching a thermocouple to the group, at least during your period of famiarising yourself with the machine. Where you place the tc, and whether or not you insulate it, won't matter much, as you are concerned only with relative temperatures for your group.
Matt.

Frans Goddijn

Another method without measuring devices is to leave the first shot out of the grinder below the grinder, that smells good, use the next shot out of the L1 to make a cappuccino for a family member and make the third shot for yourself with the freshest possible grinds and a machine that's up and running ;-)

Jack Blackmore

haha in that situation I'd just end up drinking two doubles and my morning would be off to a shaky start indeed!

I should probably mention I had a little play around last night and have been doing a short flush after each shot and it's purring like a dream! This morning I just walked up and both shots were amazing.

One little tack on question, I'm finding that when I unlock the portafilter is sounds like air is getting sucked in and it's sometimes shooting coffee up into the grouphead. To get around this should I unlock the portafilter earlier rather than waiting for it to stop dripping?

Salvatore Taibi

Jack,

As to your last question, there is no way I know of for anything "to be sucked in" unless you are pulling the lever. On a pump machine, this does occur, but not with a lever. The sound you are hearing is most likely air pressure that has not escaped yet. Waiting longer before removing the pf would alleviate the issue, although in my experience if I have to wait more than a few seconds it is a grind issue. If you need to remove the pf at a quicker pace, a slight tug on the lever will reduce the pressure and you can practically pull the pf immediately. Of course, doing so certainly creates a situation where you are pulling some air (along with H2O and coffee particles) into the group.

Regarding ambient temperature, I have found the LI to be incredibly sensitive to temperature changes. I have a probe on my machine, and while I don't really need it very often, it is fascinating to see how the slightest air fluctuation can effect changes. Blow on the group and you can see it vary! To this point, as has already been stated, I have found air current (air circulating due to open windows, fans, or vents) to have a far greater impact on group temperature than the ambient room temperature. I live in a very warm environment, and the ambient temperature does not vary much over the course of the year. Despite this, the room where I have my machine has a ceiling fan. If I change the fan speed it can move group temperature dramatically. Your best bet, without even using a probe or a thermometer, is to simply dial in the temperature based on taste. It is pretty simple, really, and once you find the temperature and pstat setting you prefer, the machine is incredibly rock solid. So solid, in fact, I'm often amazed at how all day/night it is spot on the target number. Wonderfully simple yet elegant design.

Reiss Gunson

Jack Blackmore post=12313 wrote: haha in that situation I'd just end up drinking two doubles and my morning would be off to a shaky start indeed!

I should probably mention I had a little play around last night and have been doing a short flush after each shot and it's purring like a dream! This morning I just walked up and both shots were amazing.

One little tack on question, I'm finding that when I unlock the portafilter is sounds like air is getting sucked in and it's sometimes shooting coffee up into the grouphead. To get around this should I unlock the portafilter earlier rather than waiting for it to stop dripping?

no, the opposite of that; later. wait 30 seconds before removing the poatafilter and all will be good if the status quo annoys you.

salvatore is on the money with his observations about air flow over the group too.