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WiFi or remote control for Buderus G124x with 2107 - Ct-100?

kentw Member Posts: 4
I have a G124x, 2107, and BFU/room sensor. The system is at a 2nd home. I would like a way to adjust the heat remotely. Can the CT-100 be used with 2107? Any other options that would give me remote control.

When we leave the house we set the RFU to night and 55 degrees. It takes 6 hours or so after we arrive to warm the house up - DHW takes priority for about 2 hours, then the radiators start getting hot water.

Thanks for any ideas, Kent
Colorado Springs


    HVACNUT Member Posts: 5,876
    Not familiar with the Samsung tstat or its reliability but it shouldn't be a problem. Looks like battery powered so you don't need a common.
    Why a 2 hour recovery on the water heater? Do you turn down the temp via the Logamatic when you leave?
    Just 1 zone with the tstat wiring going into the Logamatic or to a zone board signaling a heat call to the #63 terminal on the Logamatic?
    If it wasn't a problem with the manual tstat, it shouldn't be a problem with the WiFi stat.
    P.S. the 2107 has programming for vacation mode, day/night and scheduling.
  • kentw
    kentw Member Posts: 4
    Thanks, I should have been more specific. The CT-100 I am looking at is a new Bosch WIFI RFU -


    The Bosch press release for the CT-100 only mentions GB142 and GB162 but I was hoping it could be made to work with 2107.

    We use the RFU night mode when we leave to put the 2107 in manual mode to shut off DHW when we are gone. We are gone 2 weeks a month in the winter.

    I could use vacation mode on 2107 but still would like a way to remotely turn heat up so the house would be warm when we arrive.
  • kentw
    kentw Member Posts: 4
    Another option - I could build a custom interface with a raspberry Pi if I could figure out the interface between the BFU and 2107. How does the room sensor communicate to 2107 - what protocol?
    HVACNUT Member Posts: 5,876
    Sorry. Place a call to Bosch Buderus. I don't know if you can use a Bosch control with a Buderus.
  • Wellness
    Wellness Member Posts: 143
    edited March 2017
    For HVAC remote control, I highly recommend the X-300 Web-Enabled Temperature Monitor & Thermostat by ControlbyWeb. It's a little geeky but endlessly flexible and, in my experience, highly reliable with good tech support. You'll need to buy a temp probe for your application. You can see my application here.
  • mxfrank
    mxfrank Member Posts: 22
    I found this unofficial explanation on a hacker site, can't vouch for accuracy or completeness:

    Heating interface / BFU

    Jump to: navigation, search
    Table of Contents

    1 interface Logamatic 2107 with remote control BFU
    1.1 Electrical specification
    1.2 Protocol
    1.2.1 Data from the BFU to Logamatic
    1.2.2 Data from Logamatic to BFU
    1.3 Message content
    1.3.1 Errors
    1.4 Further observations
    1.5 references

    Interface Logamatic 2107 with remote control BFU
    Electrical specification

    The signal at pins 19 and 20 can be tapped on the ribbon cable between the network / relay card (module NM282) and the operating unit (module CM222). See also Heating interface / Logamatic2107 # Pin assignment of ribbon cable

    Pin 19: OUTPUT Logamatic 2107 => BFU
    Pin 20: INPUT BFU => Logamatic 2107

    It is a UART signal (0V low, 5V high) according to RS232 with 1200 Baud, 8N1. The signal is converted by the relay card to a level of 12V low, 15V high. The transformed signal is available at connector BF on the relay card for heating circuit 1 (HK1) and at connection BF2 on the mixing module (FM241) for heating circuit 2 (HK2).

    The transmission of data is done by exchanging 1-9 byte messages. Control messages always start with 0xA ?, data messages start with 0xF ?. At the directional arrows on the left is Logamatic 2107 and on the right BFU. With every transmission the Logamatic starts the communication. The answer of the BFU decides the direction of the data transmission.
    Data from the BFU to the Logamatic

    => 0xAF
    <= 0xAC; reversal
    => 0xA0; REQ
    <= <DATA-BFU>
    => 0xA4; OK

    Data from the Logamatic to the BFU

    => 0xAF
    <= 0xA0; REQ
    => 0xAF

    => 0xA4; OK

    message content

    0x84 for HK1,
    0x88 for HK2,
    0xB8 (??? for radio clock in BFU / F).
    0x04 for HK1,
    0x08 for HK2.
    DATA BFU: 9 bytes

    , unit unknown
    , unit unknown
    , unit is 0.5C.
    , Unit 0.5 C.

    0x00 night manual
    0x07 automatic
    0x01 day manual
    0x0F short-circuit sensor external (load WW memory once)
    ???, Presumably checksum, calculation unknown.

    DATA-2107: 4 bytes

    : The byte always has the form 0x00001uvw. In this case: u = 1 summer operation, u = 0 winter operation, v = 1 automatic, v = 0 no automatic, w = 1 day, w = 0 night
    0x0F summer automatic
    0x08 night manual
    0x0B night automatic
    0x09 day manual
    : meaning unknown.


    In case of error, 0xA1 is sent.
    Further observations

    The actual temperature was measured
    Temp in C 24 23 22 20 17

    At high temperatures (hair dryer), byte will not be 0x00. More precise measurements are still open.

    Manual BFU: http://www.buderus.de/pdf/unterlagen/0005647033.pdf
    From "http://wiki.neo-soft.org/index.php?title=Heating Interface/BFU&oldid=1866"
  • ratio
    ratio Member Posts: 3,676
    That's pretty nice, @Wellness. A little limited on outputs to be a good stat, but it could disable the real stat & take control for away mode, & just restart the regular stat to initiate recovery.
  • LuRey
    LuRey Member Posts: 2
    Hi, I discussed this with my installer.
    If you have a BFU installed you can "cheat" the BFU remote controller unit.
    The BFU has extra terminals for connecting a "remote room temp sensor" that overrides the internal sensor of the BFU.
    If you connect a resistor to these terminals (by a simple internet controlled switch - eg PI GPIO) you can simulate a high room temperature and the boiler will go lower.
    Typ values for the resistor 19° = 13.063Ohm, 20° = 12.486Ohm,
    21° = 11.938Ohm.
    Switching OFF the resistor will give the control back to the BFU internal (integrated) sensor.
  • LuRey
    LuRey Member Posts: 2

    or you use a extra remote room sensor with a resistor 36k in parallel to "reduce" the temperature (this way the temp cannot go below 12°C = freeze protection)

  • Neo25
    Neo25 Member Posts: 2
    edited December 2022
    To BFU extra terminal i possible to add smart thermostat ?
    EXT/3 and EXT/4 need to connect ?