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LR preinfusion and boiler settins App

Hi everyone, especially Reiss,

I initially wanted to wait for the completed version of my mod to be on video but have now seen that Reiss is doing the exact same thing but utilizes a (IMO not so nice looking) hardware display and buttons. I am talking, of course, about the preinfusion setting.

Last time I wanted to change the preinfusion pressure on the LR I was a bit annoyed having to open the machine and check the pressure with a hand made portafilter manometer. So instead I wrote an App and a bit of software which can control the preinfusion pressure using an Arduino Nano and an industrial grade pressure sensor.

Since I read some people also complaining about the noise the pressurestat from the boiler makes, I also added a function to set the lower and upper boiler pressures which will also be measured by an industrial grade pressure sensor and controlled by a SSR relais for the heater (noiseless).

The upgrade can be done by only applying one mod to either the boiler or the preinfusion pressure or by applying both.

I did not yet install the hardware (still waiting for a smaller power supply in the mail), but added it to my Gaggia Classic Coffee test machine. In future there will also be a PID version for most "normal" espresso machines. In the case of the LR, I am not sure if PID would be necessary since the system will respond very slowly to a change in temperature and thus the heater gets longer breaks when controlled in a pressure range.

Here an image of the finished app, connections are already tested and working:


Although I want to separate something fun and relaxing like making espresso from all the technological stuff like smartphones and displays in general I think the way to go is an App to have precise control of all settings while keeping the clean and hassle free look of a classic espresso machine like the LR. Also this project could easily be expanded and updated via the App store (e.g. adding a timer to turn the machine on/off, automatic wait for a time to preinfuse and then beep, record times, taste protocolls, connect to a scale, ...)

For now it has these two functions and saves them to the internal chip. So when you want to play around you can and when you just want an espresso you do not have to worrry about anything.

If you (Reiss) are interested in my approach, I would gladly work with you. Otherwise I am looking forward to your finished solution :)

Best regards,


  • hi nico

    it looks superb, well done

    i think you're well ahead of us, we'd only slow you down

    we'll keep plodding

    kind regards

  • Speed or money is not what I am aiming for. I just want a clean solution for this and can understand if you rather do it yourself.

    Best regards,
  • If I may report here - this is not directly Londinium related - but the prototype of the app is done with a spare espresso machine. When some more parts arrive I will apply this mod to the LR, then without the buttons so you won't be able to see the difference.

    @Reiss, please let me know if it is not ok for me to post this in the Londinium forum, since you are working on something similar right now.

    It also should be fairly easy to install.

  • hi nico

    congratulations, i think your creation is superb

    that said we will not be incorporating the ability to remotely adjust the pressure transducer in the LR

    on your own machine you have the freedom to configure and develop it as you wish, but as a merchant i have more constraints

    in particular i am uncomfortable asking customers to use a third party device to operate my machines, and secondly there is the issue of support; i do not want to become the first port of call for all my customers' iPhone and Samsung connectivity issues

    if you need another example, it is the same logic that led me to decide not to offer dual fuel LONDINIUM machines, even though there is a significant commercial opportunity to do so; i decided they would simply be too difficult to properly support remotely

    so my offering will not be as sophisticated as what you have built, but it will be stable and robust and i am confident that i will be able to continue to support my customer base better than any of my competitors, and that is central to the business model

    kind regards

  • Hi,

    I wanted to post a short update on my project. If you are wondering why it is taking me so long to finish: No, it is not that complicated to build and it will be even easier to apply the mod once everything is worked out. Since I am on a budget (like with all my projects) I am sourcing the hardware from outside my country. Sadly, they first sent me the wrong pressure transducers which had an error of approx. 0.5 bar at 110 °C (ranging from 0 to 150 psi). Add the remaining errors applicable to the signal path and it will be hard to set a pressure of 0.8 bar on the machine with fast heat up time and constant range. An offset would change the result to a good pressure range but will either stop the machine from heating up quickly or blow up the boiler (haha, I know there is savety).

    The one I got after that was actually excellent. It was ranging from 0 to 30 psi and would have had a maximum error of around 0.1 bar at brewing temperature. I am still not sure why, but this sensor broke after I left the machine on for about 4 hours. My guess would be that the elements which are moved by the pressure within the transducer didn't like being under pressure, heated over 100 °C (even with this temp. being in the specs as it was rated up to 125 °C), sitting in steam and getting a current run through. Maybe it oxidized or something. First it seemed to be stuck, reading a high pressure all the time, then it had an offset of one bar constantly. During my ongoing search I noticed that even some 100+ € pressure transducers are not meant to be used in steam.

    It is actually kind of ridiculous how hard it is to find a fitting transducer which isn't 500 € a pop and which can handle this kind of environment. After an extended search I now finally got one which seems very promising from the specs sheet. It should arrive this week and I will hopefully have time on the weekend to install it into the machine and adapt the code and hardware to it.

    I am writing this post not only to ramble but also for you to see that even the smallest things can be a huge pain in the butt when dealing with these type of mods. You need knowledge of many different fields and the patience to find the errors if some occur (and they will). If you prefer a nice, complete solution, I would recommend Reiss's pressure adjuster since his version will probably be very robust. If someone is interested in my mod, I would gladly share the information on parts needed, wiring and the compiled code (not the source code) with you. We can also discuss potential changes and I would try to help you with problems but my time is very limited so it would be best for you to be prepared.

    Btw.: currently there is no iPhone version, but if enough people are interested in it, I would program one as well (probably around Q1 2019).

  • Hi Nico,

    Thanks for sharing the details of your mod! I will be looking forward to seeing the final result and the details of how you end up implementing it.
  • Hi,

    Thanks for your feedback Joshua, it is appreciated!

    So on Friday the new branded pressure transducers arrived and I switched both, the one for the boiler which was not working and the one for the preinfusion transducer, just to be save. Of course they sent me a wrong article again. This type of sensor measures the pressure in the medium against a preset pressure encased within the metal body of the transducer. Normally you would get a vented one which is at atmospheric pressure und they tell you the day and location when it was produced/vented so you could deduce the internal pressure with atmospheric changes at different days (not needed for this application) etc. Anyhow, my machine now has to subtract one bar to be at zero.

    I am happy to report that the machine was running for more than 27 hours with the panels on (hotter electronics) and everything is well. I noticed that the boiler pressure can be set even more precise by two decimal places with the manometer and pressure transducer being precise enough to notice the difference. The program(s) are already changed to accompany that and only need a few tests before being the ‘official’ version.

    There also is a separate offset available in the app, one for each transducer to negate potential sensor offsets at the higher working temperature. This was really meant for the Chinese sensors and I did not see any need to set an offset with the new transducers. But if you were to have a different reading on the manometer then set in the app, you could just set it as offset and forget about it since all readings will be automatically adapted then.

    Changes to the machine I noticed so far are:
    • No more clicking of the Sirai pressure stat (duh!)
    • Bluetooth can go through a steel casing (phew ;))
    • The pump is set to about 4.7 bar, probably because the original pressure stat can only adjust a more limited range, so why not have this as additional safety for the pump. You should be able to adjust the maximum pump pressure with a screw from the bottom of the machine.
      • I wouldn’t necessarily change the pump pressure since it should be used for preinfusion and a preinfusion of > 4.5 bar is called an extraction on some machines.
      • If you want to pump at 9 bar, get a pump machine.
      • Of course you can always try it at your own risk.

    • The pump sometimes (especially at higher PI pressures) turns on when you turn on the cold machine. This is because the pressure to the PI/heating cycle is partly lost during downtime and then restored. If you, like me, enjoy a very quiet home and are bothered by the noise when the machine turns on in the morning, you could disable or better yet, automatically set the pump to 0.5 or 1 bar for the first 45 minutes, so it will be on very shortly. After 45 min heatup time the user defined PI pressure is used again.

    I am not sure if the closed heating loop works better under pressure or if any amount of water is drained when turned off for too long, so I guess it wouldn’t hurt to keep it slightly pressurized. Also, it still can occur that the boiler is filled which would result in a longer pump noise.
    • When using the PI on the coffee, the pump may ‘stutter’ since it tries to keep the pressure at a constant level. SSRs are very fast, so in the EU you can turn the pump on/off 60 times a second. I am not sure yet if this could be a problem for the pump electronic but I think from a technical standpoint it should be fine in the long run. Maybe some people might react nervously when hearing their 300 € pump go ‘bapapapaparararawpa’. As Reiss already said in his news-post for his PI setter, this could be eliminated by a preset pressure range with the user setpoint in the middle. I don’t see the necessity at the moment; this functionality could be easily added with an update.
    • The machine also restores pressure to the cycle during runtime. I noticed it before the mod when the pump would turn on for a second or two. Now it will turn on more frequently (once an hour maybe?) but for a fraction of a second. You barely notice it. This could also be updated away by the above mentioned range.

    Btw. It is not possible to get a live pressure reading during the extraction. When you move the lever (being pulled down completely) up until the pump is shut off, you are in the position in which the PI/water cycle is shut off from the brew group. From this lever position on up the backend pressure transducer is shut off from the extraction.

    Overall I am very happy with my mod. Changing the PI pressure is fun to try but the machine can be enjoyed as simple object without buttons and dials as well. The newly gained silence with only the sound of boiling water when heating is almost therapeutic ;)

    I think anyone with the will to do this can apply the mod to his machine. You should know how to solder, though, which really isn’t that hard. A rough estimation would be around one day to solder, remove stuff from the machine, add new stuff to the machine, test and have an espresso. When you need to buy the pressure transducers at MSRP, everything together will cost you around 350 € (~100 € to 500 €). This also depends on how much you already have lying around (cable shoes, soldering wire, wire, thermal paste, …). Higher quality SSRs would also add another 100 €, gettings the Arduino in a local store adds another 18 € etc.

    Most needed parts come in larger volume, so I am thinking about making a few kits with presoldered parts etc. The actual work on the machine then includes:
    • Screwing out existing pressure stats and screwing in new ones
    • Changing some cables
    • Ziptying everything into place

    If someone has genuine interest, I can also write a manual with pictures to aid you as well as a parts list. I am not taking responsibility if you get hurt or break anything!

    I will follow up this post with a video soon. For now here are some pictures I took during the build process:

    First version with old transducers, still a bit messy.

    Still working, though :)


    Look from the top.

    Have a nice day!

  • Hi,

    I am done now. Here is a video on the new features:

    The english manual can be found here:

    The google translated German manual can be found here:

    The App is live on Google Play:
    Espresso Settings App

    I enabled comments in the documents in case anyone wants to participate. I decided to go through the code/setup with the first person attempting this mod so we can check that the code and everything is correct in the manual(s). After that I will upload the compiled code and a manual how to apply it to the Arduino.

    The manual is written as precise as possible and additionally has an image guide on all parts and connections. The original pressurestat can now also be reused as additional safety feature to shut off the system. This is especially nice for people who like to turn on the machine while sleeping or being not home (yet) without having to worry.

  • hi nico

    congratulations, well done on making it happen, you've done a great job

    as a side note if you run the boiler much above 1.0 bar the thermosiphon will flash boil when you pull a shot, causing the thermosiphon to stall, and then the group temperature becomes erratic, with erratic extraction following. the higher the pressure in the pre-infusion circuit the more likely it is that flash boiling will occur when the shot is pulled

    furthermore, movements in the boiler pressure only produce tiny movements in the brew temperature

    by elevating the pre-infusion pressure instead you have the ability to significantly raise the brew temperature (& brew volume) by blowing the water out of the heat exchanger (at a temperature of around 125C) and into the brew chamber so much faster (due to the higher pressure) that it arrives at the puck much hotter, as the group has less time to suck the heat out of the water

    my suggestion to all users of our LR/1/2/3 machines is to keep the boiler pressure at 1.0 bar and flex the pre-infusion pressure instead; that is the big discovery if you like in terms of making a lever machine being able to obtain good results from all roasts, dark, medium, or light whilst maintaining a thermally stable system

    kind regards

  • Hi Reiss,

    thank you for the compliment!

    Thanks for the info as well. As I said in the video, I tried to keep the original boiler pressures since you probably put alot of thought into it. It was a bit higher then before and the water actually started to flash boil after a while when pulling the lever. I adjusted it down a bit, now it should be fine. That's what the settings are for :) Preinfusion pressure is very nice to play with. I rarely found the motivation before when having to lift the top off and guess the pressure using only a screwdriver. It can make a huge difference taste wise.

    Update on the mod:
    [li] I found the problem with the casual resets of the Arduino mentioned in the video. Just don't ground the SSRs. I am not 100 % sure why this caused problems, maybe because the opto-coupling of the SSRs did not work properly when grounded on the backplate. Either way you should be fine since the LR casing is completely metal and also grounded by default. Also when you get the black anodized heatsink for the SSRs, it won't conduct electricity that well.[/li]
    [li] I ordered the first prototype of a circuit board for the mod. If all is going well I could supply a few people with presoldered and preprogrammed hardware, so all thats left to do is changing the wires and sensors in the LR.[/li]

    I keep you updated.


    P.S. I don't get notifications on private messages and you probably don't either. You can also contact me at [email protected]. I think it would be best to use the forum though, since someone else might have a similar question.
  • As promised there is a PCB-version now. You can order the PCB online from a manufacturer and solder it yourself, which takes about 10 min. Parts are also included with the BOM file ( ). I already build it and it works great. I could remove all of this (with some additional test hardware to get rid of the resets):

    And now it looks like this:

    With the PCB all components can be connected directly i.e. no more soldering of resistors to wires for the pressure transducers etc. Since the PCBs are ordered in bulk I have 8 pieces remaining. If someone is interested I could send out a few complete kits. The bluetooth module can also be inserted at an angle to get a lower profile:

    Attached files (14.2 KB)  image image image image image
  • Good news everyone! :)

    I think I figured out the reset problem. It seems it was only a question of placing the Arduino better within the machine. I admittedly just cramped everything in the corner. With the new pcb I isolated the back (add thick tape to it) and gracefully slid it between the water tank and backplate with the Arduino being on the water tank side. The SSR backplates are also not connected any more, so you can leave that step out from the build process.

    For now I tested six times the following situations:
    Either the heating being constantly on and the boiler being refilled, or the boiler being refilled during which the heating was switched on.

    These caused resets in the past approximately one in three times.
  • Joshua tipped me off that Scott Rao is getting a significantly higher extraction by preinfusing at 4 bar and letting the puck soak (without the pump turning on during that time) for 30 seconds, then starting the extraction (
    I started working on an update which will allow you to select if the pump should try to keep the preinfusion pressure at the set level or if it should wait for the puck to soak with a gradually falling pressure (due to the soaking). The machine code already seems to work. The interesting part was to find a way for the machine to know from what little information there is if the lever was pulled and if so, whether you are flushing the group or you want to preinfuse.

    Here some screenshots from debugging:


    [li]Yellow: Lever up, idling. The measured ‘current pressure’ is at ~4 bar. This is caused by the lever pushing part of the water back into the thermo syphon channels before the ‘open loop’ is closed again by the piston (I think).[/li]
    [li]Red: Started PI, pressure drop is detected as flush at first, PI pressure is restored by the pump[/li]
    [li]Green: Start of PI phase with overshoot of the pump (it can’t stop from one millisecond to the next). During this phase, with the update applied, the pump won’t turn on again[/li]
    [li]Green, second image: Still dropping pressure from preinfusion[/li]
    [li]Orange: I started raising the lever slowly, start of extraction is detected (firstPIOffCycle turns from false to true again).[/li]

    Keep in mind that I use old coffee for testing purposes so don’t compare max. pressure etc. to your perfectly tuned setup ;)
    Now the app needs to be adapted. I am also thinking of adding two timers, one for PI and one for extraction.

    @Reiss: If you like you can share the communication interface. Maybe it’s just a small change for my app to make it work with your hardware.


    Attached files

  • The first update is available now!
    As mentioned before a noticeably higher extraction can be yielded by protracting the pre-infusion WITHOUT keeping the high pre-infusion pressure which would turn into a slow extraction instead. This option - to have the pump turn on only once per pre-infusion - is now available through my app and hardware mod. Additionally I played around with what little information is available about the pump pressure and managed to add following features:

    [li]Automatic pre-infusion start detection with a timer.[/li]
    [li]Live pressure view during pre-infusion (after PI the pressure would read the internal pressure in the pipes.[/li]
    [li]Automatic start-of-extraction-detection which will stop the pre-infusion timer and start the extraction timer.[/li]
    [li]Manual stop for extraction timer.[/li]
    [li]All parameters are kept until a new espresso is brewed in which case everything automatically resets and starts anew.[/li]

    While these new features probably won’t work 100 % of the time, they should be pretty reliable with a normally dialed in setup (e.g. no water rushing through the puck during pre-infusion). The option to turn the pump on only once per pre-infusion is working really well for me so far.
    Of course you are still free to choose the normal operation of the LR with the pump trying to keep the pre-infusion pressure at the set level. This now also works more precisely with a precision of about two decimal points.
    I think I didn't mention it before but you can of course only build the pre-infusion part of the kit without touching the boiler pressure stat. The mod then only requires to connect 4 wires to the machine.

    The overall price of the kit including pre-build PCB and programmed components, one pressure transducer, one SSR, power supply and cables would be around 200 € depending on shipping and customs (except EU in which I live). If you already built my mod and want to update please get the update from the app store as well as for the Arduino to upload (using a PC/Mac). Espresso Settings App on Google Play

  • Congratulations Nico this is really advanced implementation! The soft pre-infusion opens up additional possibilities for increasing extraction on lightly roasted beans and really takes advantage of the Londinium R's unique capabilities that other espresso machines don't have. Nice implementation with the shot timer as well, that is a nice feature.
  • Hi Nico,
    are you still using this mod ? or have you abandoned it ? ....have you done any further progress/other etc. etc.

  • Hi Darren,

    Yes, I still use the machine with this mod installed every day. I don't play around with it that much any more but still adapt the settings on a bean or taste change. There were plans for a wifi version but currently I don't see the need for it. Of course one could then also do a lot of statistics etc. but I trust in the knowlede and engineering of Reiss that the machine is at its best already :) Maybe an iOS version of the app would make sense but seeing as there was no demand yet and I don't own any apple devices any more...
    My current project is a fully embedded Artisan compatible/standalone wifi module for the Gene CBR-101 roaster, if you're into that.

  • Hi Nico,
    sorry for the delay in answering; been busy altering my kitchen etc. etc.
    How stable is the temp? the group thermally stable with your mod installed ?

    The roaster project sounds interesting but it's waaaay beyond my skills at the moment.....roasting sounds cool, something i may consider in the future.... i will still look at your project there a video/link/other to it to look at ?

    Take care and stay safe.

  • Hi Darren,

    I did not measure any group temps at any point. That's why I got the LR. I never had any problems with stability or anything else with the machine. The SSR on the heater is only for noise reduction since the click annoyed me. The profile is set to heat in the same range Reiss suggests and with which the machine gets delivered. Preinfusion pressure will have a bigger influence on the coffee then the boiler on this machine. I also don't do any flushes besides cleaning.
    Did you run into trouble with you machine?

    You can have a look at the current official (LCD) version here: There is also a video linked at the bottom as well as the documents to build the mod for yourself :)
  • Hi Nico,
    again many thanks for replying and for the roaster-mod-link/url....i like reading about what people do with stuff they've purchased and then adapt etc. .....looks interesting.

    As for "Did you run into trouble with you machine?" yeah but it's sorted now; i do have another "worrying matter" but i will post that in the relevant section on here...going looking for the section now.

    Take care and stay safe.
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