Thermostat for Viessmann Vitodens 050-w

Discussion in 'Plumbers' Talk' started by Geza, Feb 22, 2016.

  1. Geza

    Geza New Member


    I bought a 2 bedroom house and I found a brand new Viessmann Vitodens 050-w installed but it doesn't have a thermostat. All the radiators have TRV's but in order to heat up the property I need to leave the boiler on all night and I have to set the desired temperature of the water in the radiators (70 degrees for example) and then let the boiler circulate and heat the water all night long.

    A friend of mine has a brand new Vaillant and he bought from screwfix a wireless Flomasta thermostat and after watching some YouTube videos he was able to install it on his boiler (he is a handyman)

    So I bought the same wireless Flomasta thermostat from screwfix but I don't know exactly how to install it.

    I read the instructions and there was something about volt free connections and I have a 4 pin connector on my vitodens 050-w but in the manual it said that those connectors have 230 volt in them.

    And now I am a bit puzzled.

    I have a connector on the boiler with 4 wires.

    1 - white
    2 - brown
    3 - black
    4 - blue

    And at the moment there is a small bridge cable between 1 and 2 (white and brown cables)

    On the other site there is the thermostat with 2 pieces, one wired and one without wires. The wired one has exactly 4 coloured cables coming out at the end of the main cable and the colours are similar to those on the boiler.

    Does anyone know where exactly do I need to connect those 4 wires from the thermostat to the boiler?

    I will upload a picture of the connector on the boiler. 2016-02-22 15.22.29.jpg
  2. According to this on page 21: 050 BPJD Install and Service Manual.pdf the terminals 3 and 4 are for an outside stat.

    This may be useful if it controls the modulation of yer boiler. Ie - it'll run hotter during cold days but automatically cooler in milder weather - making it more efficient.

    Anyhoo, the other terminals - 1 and 2 - are for the room 'stat you are after.

    That link is removed and the stat's 2 switching terminals are wired in there.

    Any electronic stat will do, battery or mains. For battery type, all you need run to it is a 2-core cable.

    Will it be easy to get a cable from the boiler to your room stat location? If not, consider going 'wireless' - they will also work.

    So, find yersel a good stat you are happy with, and we'll tell you how to wire it up.

    Also consider a Programmable Room Stat - they are awesome.

    Finally, only consider this if you are competent.

    Finally finally, the TRVs of the rads in the room that'll have this new stat will need to be opened up to max and left like that.

    Anyhoo - let us know.
    Geza likes this.
  3. Geza

    Geza New Member

    Thank you for your reply. I will upload some pictures with the thermostat I bought from Screwfix. It is a wireless one. But I think it needs power from the boiler (hence the 10A fuse recommendation for the grey wire)

    2016-02-23 06.13.15.jpg 2016-02-23 06.12.16.jpg 2016-02-23 06.10.32.jpg 2016-02-23 06.11.06.jpg

    EDIT: Where can I find a inside/outside thermostat? I never heard of such a thing before. I like the idea of efficiency.
  4. First the easy bit - your stats's receiver's BLACK and GREY connect to your boiler's 1 and 2. (They can go either way around, but best go for black to 1).

    Then your receiver needs mains power.

    Ok, this MUST come from the same isolating switch that you boiler uses, so that turning off that ONE switch turns off EVERYTHING to do with your boiler.

    There are two ways to do this; the best is if your boiler has spare L and N terminals inside it you can connect to. That means you'd use a 4-core flexible heat-resistant cable to connect your receiver to your boiler - 2 wires for the stat's switch and 2 for the stat's power. (No earth needed since the receiver is double insulated.) That would be neat, and the stat would get its power via the boiler - so one switch does all.

    Alternatively, if you cannot find power supply terminals inside your boiler (I couldn't find anything about it in the instructions I linked to - but I'd be surprised if they weren't there) then you'll need a separate cable from the boiler's isolating switch to the receiver. More clumsy - two 2-core cables going to the receiver. In this case, the cable from the isolating switch to the receiver can be surface-run 1.0mm2 T&E - the type of 'stiff' cable used for wiring yer hoosie's lighting. In which case, connect the earth wire inside the switch, and terminate it inside the receiver - hopefully there's a terminal inside for this.

    Can you show a photo of the isolating switch your boiler has?

    As for the ext thermistor - try contacting the manufacturer :rolleyes:
    Moscalu Ionut likes this.
  5. Geza

    Geza New Member

    You were right, there is no cable for 230V, you must buy an addon:

    2016-02-23 14.50.28.png

    2016-02-23 14.51.15.png

    And also I found the weather compensation device:

    2016-02-23 14.52.02.png

    So I ordered them today, and I will let you know if everything is OK after I will install them.

    Thank you for helping me!

    EDIT: I wonder if this weather compensation sensor will work with the Flomasta thermostat that I have.
  6. Cool - it was definitely worth getting the connection box as it makes things much neater.

    Ditto for the weather compensator.

    These two items are quite different, and do very different jobs, so one won't interfere with the other.

    Your room stat is...well, you know what it is :rolleyes:. And you wisely went for a Prog Stat too, so that's all the timings and temps taken care of :).

    Your boiler is a 'condensing' type, so is more energy efficient. And the cooler it runs, the more efficient it is - it can extract more heat from the burnt flue gases if the water in it is cooler. So, ideally, you'd keep adjusting it over the year so it runs as cool as possible, whilst still - of course - being able to heat your home.

    The weather compensator does chust that - in cold temps it'll turn your boiler output upski, and then back downski in milder times.

    Happy New Weather Comp Thingy.
  7. Chris Peters

    Chris Peters New Member

    Hi I'm trying to connect to hive and was wondering what was what when it came to wires 1234
  8. Hi Chris.

    I'm assuming the Hive has L and N and then 'COM' and 'NO'?

    The L and N will be to power it, and the com and no are the actual 'switching' contacts.

    As you will have read from this thread, you essentially connect the Hive's COM and NO to 1 and 2 on the boiler. But the Hive will also need mains power, so you'll need to arrange that too; this MUST be from the same power source as feeds the boiler so that only ONE switch controls it all.

    How does your boiler currently get its power? Is the an FSU beside it?
  9. Chris Peters

    Chris Peters New Member

    Hi . Thamks! yes the fuse spur is next to the the boiler.I think why I'm struggling is that I need to get that electrical connection unit for the boiler as I've since learnt that the 1234 connection is the external temp sensor and inside the boiler they have module connections not terminals
  10. Chris Peters

    Chris Peters New Member


    Attached Files:

  11. Chris Peters

    Chris Peters New Member

    The hive unit has a permanent L. permanent N a common a heating off (NC) and heating on( NO )
  12. You can see from the original example, the OP (Geza) had to buy an extension 240V connector to make his work.

    I can't that that's necessary, but you'll otherwise need to be able to get a 240V supply from the boiler or the FSU.

    Trace where the 240V cable from the FSU enters the boiler and connects to it inside - can you find these terminals? Cool. Can you connect a further cable to these? You may need to undo the existing one at a time and twist the strands from the new cable on to it and re-insert. This should include a L, N and E (your Hive won't actually need an 'E' being double-insulated, but the cable should really have one running through its length).

    Ok, does it look as tho' you can manage that? Cool. But don't stick a cable in there yet. (AND, this cable should be flexi and heat-resistant, probably of 1mm2 or 1.5mm2 size - there's special cable for this.)

    That just leaves a further two wires - again flexi stranded type - which will connect the boiler's 1 and 2 to the Hive's COM and NO.

    So, what you really need is 5-core flexi heat-resistant cable (2 x mains power, 2 x switching, 1 x earth).

    Is you Hive a wireless type? If so, then this cable will be short as the receiver will almost certainly be fitted close to the boiler. If the Hive is a wired type, then this cable will have to be as long as the distance betwixt the items. In the latter case, it would be usual to run the main length of 5-core (or 4-core + E) cable in solid core type, and clip this securely to whatever surface it runs along. But you'll still need that bit that goes in to the boiler to be FLEXI and HEAT-RESISTANT, so that will likely involve fitting a JB close to the boiler to connect them both.
  13. Chris Peters

    Chris Peters New Member

    I have a separate 3amp fuse spur running my reciever so obviously that is where im getting my permanent live , neutral and earth . That leaves 3 more terminals in the hive which is common ,hot water on and hot water off. The only terminals on the boiler apart from the mains supply are the 1234 terminals as shown in the original thread so if C and NO are the other two which is NC or as in a regular switch do I just put a permanent feed loop to the common and put the other 2 in NO and NC. Sorry if I'm complicating matters or am missing something,I really do appreciate the help!
  14. Since you have power going to your receiver, then all you need to make this system work is to connect the Hive's COM and NO to 1 and 2 on the boiler.

    HOWEVER, my understanding is that you have broken building regs by having two separate power supplies to parts of your CH system. Plumbers should feel confident that they can isolate the WHOLE system from a SINGLE isolation point 'cos they don't like being 'cuted.

    Where is the FSU for the boiler and where is the FSU for the Hive's receiver? Photo?

    If they are anywhere in the same area (and surely they are?), then why not add the flexi from the receiver in to the same FSU as the boiler's?
  15. Chris Peters

    Chris Peters New Member

    That's no problem as I can make the power supply come from the boiler and ditch the fuse spur as I have plenty of access to the power cables and haven't wired it in yet.tbh I had thought about the fact of 2 power supplies going to the boiler being stupid last night! Will give it a go later when I get back from screwfix with the bits. Again I can't thank you enough for all your help!
    Deleted member 33931 likes this.
  16. Chris Peters

    Chris Peters New Member

    Works a treat. Thanks so much for your help! Truly a living legend!
    The only thing I didn't mention was that it was already running a wireless stat so for anyone else that finds these threads helpful just unplug the internal wireless reciever on the boiler and it works perfectly .
    Deleted member 33931 likes this.
  17. TonySuth

    TonySuth New Member

    Hi folks, I’m having real difficulty with my thermostat and Viessmann 050.
    I’ve got a Honeywell T6R plugged in and it works absolutely fine for a few hours then the boiler stops receiving the signal from the receiver. The thermostat receiver has the green light on stating that it is sending a signal to the boiler to heat the house but the boiler isn’t receiving it. When I turn hot water taps on though, hot water is fine. Plumber said the boiler is fine and works no problem when isolated from the thermostat with the link wired between the wiring block in ports 1 and 2.
    As far as I can see it’s wired all correctly? I’ve also had an entire replacement Honeywell T6R kit sent out and installed it again just in-case the first was faulty. But the same issue persists. I know the exposed wire in the pictures are slightly on the long side, but until it’s sorted I’m just doing temporary wiring, so excuse the slight untidiness.

    Attached Files:

  18. Jojo518

    Jojo518 New Member

    Has anyone connected a Nest E Thermostat to their Viessman Vitodens 050 yet?
  19. ABitCold

    ABitCold New Member

    Hi Tony. Did you resolve this problem?
    I'm having a similar issue.
    I have a Viessmann Vitodens 100 with a honeywell wireless thermostat.
    Boiler doesn't come on in the mornings sometimes and I have to twiddle the thermostat down and back up again and then it does...mostly, or I have to turn off and on boiler and then twiddle down and back up. And it just stops going in the day but the room is below temp, the timer is on and the Honeywell green light is on.
    I have just had boiler serviced and no change.
    I am suspecting control panel PCB and/or timer faults.
    No fault codes show on the boiler. It just turns off the CH.
    The boiler can work for a few hours prior to stopping.
  20. Brittan Smith

    Brittan Smith New Member

    I also have an issue with viessmann wb1b 100 it isnt getting to temp in my house. I just had it serviced today and the tech left scratching his head. I have a 2-wire thermostat currently and I purchased a honeywell t5+ wifi thermostat and the tech could not figure out how to wire it in to the system. I have the c-wire adapter and have no clue as to how to wire it in. I'm very capable of doing so just need help with some pictures of what wires go where.

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