I recently purchased a Londinium LR; while researching the machine I noticed a dearth of information regarding the temperature stability of the group. Coming from a heat exchanger E61 machine I was aware that temperature stability is not generally a strong point of heat exchanger design in general (without cooling flushes, etc) but Reiss and others on various forums claim the machine to be very stable, stable enough to be used in commercial environments even. After receiving the machine and getting comfortable with it I set out to put this hypothesis to the test with the tools I have available to me; namely a Scace unit, a thermocouple with eyelet hooked up to the bolt where the spring assembly meets the group, a bare wire thermocouple for measuring air temp, an Amprobe TM-56, and computer running artisan.

In the first temperature study I took 8 shots back to back with 3 minutes in between shots. After each shot completed I took the Scace unit off the machine for 1 minute to allow the plastic puck to cool a bit (since this represents a coffee puck that would have been dumped and reloaded with room temp coffee)



The next temperature series was taken the next day. This was 5 shots taken back to back in the same manner as the first series above (3 min between shots, Scace off machine for 1 minute after each shot). The only difference is that I preheated the Scace unit with 208*f water prior to locking in the unit as I theorized that this may have lowered the temp of the first shot in the series the previous day.



So far I was extremely happy with the temperature stability in pulling back to back shots. In the time that I have been using the machine I noticed that the grouphead temperature varies between 177*f at it's lowest and 182*f at it's highest and this is in correlation with the temperature of my house and more importantly how hard the A/C is blowing; I saw this effect on my previous E61 machine as well. I wanted to quantify how much of a difference this might be having on my shot temperatures so I started the next series in the middle of the day with my houes and A/C at its normal settings. After pulling the first shot I turned the A/C way down and pulled shots over the next hour or so. My A/C was blowing at max continuously, to the point that it shut off afterwards because the drain pipe was somewhat clogged and got filled up with water shutting off the safety switch, lol. I used a bare wire thermocouple to measure the ambient air temp and then prior to taking the shot I switched the channel to the Scace unit instead. For this series I did not remove the Scace from the machine. Note that ambient air temp started around 76-77*f and ended around 70*f; The Londinium grouphead temp started at around 182*f and ended at around 177.5*f; it is not just the change in ambient temp that effects the grouphead temp but the constant blowing of the chilled A/C air.



In this series I was able to visualize the variance in grouphead temperatures that I see in normal use with the machine and their effect on shot temps which seems to be within about a degree of the starting shot temp; very happy with this as well.

In the end I was very pleased with the results of the temperature study and suprised by the temperature stability of the machine, both in continuous use shot after shot and in the differing temperature/ A/C blowing conditions encountered in my house.

Of note, the max shot temp as measured by the Scace device on these studies is way above what you would like on a pump machine but this device does not show true shot tmax on lever machines for some reason (hypothesized elsewhere). This has been discussed already in multiple threads (see link following, there are other threads out there too) but I can confirm that my shots have been tasting very good and not burnt (shots >/= 205*f on my e61 machine tasted veyr burnt). Regardless, the Scace is still the ideal tool, in my opinion, to measure temperature stability/repeatability of shot temps.

Apparent Overheating of Lever Espresso Machines Measured with Scace Thermofilter

Madman13 wrote:Of note, the max shot temp as measured by the Scace device on these studies is way above what you would like on a pump machine but this device does not show true shot tmax on lever machines for some reason (hypothesized elsewhere). This has been discussed already in multiple threads (see link following, there are other threads out there too) but I can confirm that my shots have been tasting very good and not burnt (shots >/= 205*f on my e61 machine tasted veyr burnt). Regardless, the Scace is still the ideal tool, in my opinion, to measure temperature stability/repeatability of shot temps.

Apparent Overheating of Lever Espresso Machines Measured with Scace Thermofilter

The Scace will show you the true shot temp if you use the correct testing procedure for a spring lever. This was covered in that thread you linked to.

Are you referring to covering the hole in the bottom of the scace output during preinfusion? I don't believe it was definitively shown in any way that this would accurately display shot temps in lever machines and I belive this still results in temps that are higher then what you would expect compared to pump machines. I decided not to use this technique in order to not introduce another variable into the temp study.

And that is why your temps are so high. You aren't duplicating the way a spring lever works you are just running water through the group. I did this initially when I started testing my Bosco. I quickly figured out the problem & was able to accurately see my brew water temps during testing using that method I described in the linked thread.

During normal use the group fills when you lock down the lever, the puck keeps the water in the group allowing minimal absorption & the group/puck/pf combo pulls heat out of the water before you lift the lever. Try my test method & see if your readings don't look a lot more like the brew temps you know that you are getting.

Madman13 wrote: ...a thermocouple with eyelet hooked up to the bolt where the spring assembly meets the group...

What bolt is that? I can't picture where you mean. Thanks.

mathof wrote:What bolt is that? I can't picture where you mean. Thanks.

This one


I originally affixed a thermocouple with exposed junction lower on the group with silicone self fusing f4 tape but the reading was not totally stable, when I touched the wire the reading would jump around so I affixed an eyelet thermocouple to the upper bolt instead.

Here is a picture of the whole setup:

JohnB. wrote:Try my test method & see if your readings don't look a lot more like the brew temps you know that you are getting.

Fine, when I get a chance I'll run a repeat series of 4 or 5 shots with your method and then we can compare the differences

Thanks very much. Your results show the L-R to be amazingly stable. I wonder if my L1 is its equal.

Matt