Wiring a room thermostat, could do with some wire help pleas

Discussion in 'Plumbing and Central Heating' started by valmiki, 15 Apr 2010.

  1. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    Hello all

    Long time lurker, first timr poster - now that I need some advice!

    I'm sure you knowledgeable peeps can sort me out.

    I've taken some pics to help explain my situation...

    My current room thermostat is a Sunvic TLX 5201

    [​IMG]

    Which I want to replace with a programmable thermostat, A siemens RDJ10-GB, to take over the timer that's on the boiler, primarily because the boiler timer can't help with setting automatically a separate night time temperature. It requires 3 feeds as standard, LX, L1 and L2.

    Opening my current thermostat, and inside is a wiring diagram (I couldn't find installation instructions anywhere):

    [​IMG]

    [​IMG]

    Here's some pics of the actual wired-up thermostat:

    [​IMG]

    [​IMG]

    At the other end of the wiring, at the Powermax 155x boiler (I know, I know!), it looks like this:

    [​IMG]
    The white cabling at the bottom is the feed from the thermostat.

    The fitting instructions from the installation booklet for the boiler:

    [​IMG]

    [​IMG]

    I'd appreciate if someone could help me out, all I want to know is which wires currently in use would be the ones I need to use with the new thermostat, ie. the LX, L1, L2. Also, I may have to do some wiring at the boiler end.

    If I've missed anything, please ask me - I'm more than happy to investigate further.

    thanks in advance!

    valmiki
     
  2. imroberts

    Joined:
    18 Jul 2007
    Messages:
    283
    Thanks Received:
    13
    Country:
    United Kingdom
    I'd say red to LX and yellow to L1, and terminate the blue cable in a choc block, as this will be an unneeded neutral.

    Make sure your power is off before you start as well, as it looks like it's a 230V switching on the thermostat.

    Don't go wiring it up until someone else has confirmed they agree with me though, I'm tired :eek:
     
    • Thanks Thanks x 1
  3. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    thanks very much, I appreciate you taking the time

    The manual for the thermostat I'm planning to install is here, the download link is about halfway down the page.

    As for the 5-core goes, it disappears behind the plasterboard as it is and I've no idea after that - that did confuse me a little.

    thanks again

    valmiki
     
  4. imroberts

    Joined:
    18 Jul 2007
    Messages:
    283
    Thanks Received:
    13
    Country:
    United Kingdom
    Don't worry about where the 5 core goes, I was over-complicating things!

    I've edited my original post now :)
     
  5. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    ok cheers, I'll wait for someone else to give me the green light too ;)
     
  6. imroberts

    Joined:
    18 Jul 2007
    Messages:
    283
    Thanks Received:
    13
    Country:
    United Kingdom
    Do you have a multimeter?

    If my assumptions above are correct, you should find 230V between red and blue, and should find continuity between red and yellow when the thermostat is operational (i.e. demanding the boiler to be on) and open circuit when it's upto temperature.
     
  7. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    I haven't I'm afraid...
     
  8. stem

    Joined:
    20 Jul 2005
    Messages:
    1,982
    Thanks Received:
    289
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    From the diagram on your original thermostat the original wires are identified as:

    Red wire = Live = terminal 1
    Yellow wire = Heat (Switched live)= terminal 8
    Blue wire = Neutral = terminal 2

    At your new thermostat

    LX= Live = Red wire
    L1= Switched Live (heat) = Yellow wire
    L2 is not used

    Isolate the blue neutral as it's not required (whatever you do don't connect it to L2)

    So imroberts is correct.
     
  9. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    stem

    Brilliant!, I'll get on to it this weekend and post back

    thanks again
    valmiki
     
  10. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    sorry about the wait, only had time to fit it this morning

    result:

    [​IMG]

    thanks to imroberts and stem

    JUst like Colombo, I have one final question though...

    [​IMG]

    On my boiler controller, would I leave it on the 24hrs setting, so that the boiler will only be controlled by the room thermostat?

    currently the switch on the left is on the 'I' 'Timed' setting (different from in the pic, I was fiddling to see what worked) and now the room controller works as it should, but doesn't this mean that the hot water is on continuously as well, or is that not an issue?

    huge thanks!

    valmiki
     
  11. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    To carry on from my previous post, the instructions I've posted earlier mention some wire arrangements at the boiler, would I need to do this?

    thanks
    valmiki

    [edit] just rang the Potterton helpline, looks like I don't need to do anything. The 155x has a cylinder but it is only used for CH, hot water is on demand only. Cheers valmiki.
     
  12. imroberts

    Joined:
    18 Jul 2007
    Messages:
    283
    Thanks Received:
    13
    Country:
    United Kingdom
    Glad it all went to plan :)

    Your wiring could certainly be simplified, as I mentioned before you seem to have 5 core cable leaving the boiler and only 2 wires are needed at the thermostat... but if it's all working and you don't want to start ripping wires out and replacing them then I would leave as is.

    The wiring as you've connected it is as it should be, your configuration falls under paragraph 5. i.e. you have a clock type thermostat connected to pins 27 and 28 in the boiler.
     
  13. DP

    DP

    Joined:
    10 Dec 2003
    Messages:
    6,949
    Thanks Received:
    877
    Location:
    Glasgow
    Country:
    United Kingdom
    Glad it has worked out. I must say the unit looks very unsightly. My choice is Danfoss TP 5000Si which looks dogs whatsit anywhere.
     
  14. stem

    Joined:
    20 Jul 2005
    Messages:
    1,982
    Thanks Received:
    289
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Looking at the built in programmer at your boiler, there appears to be two channels, one marked (HW) hot water and the other (CH) central heating. Why not set the CH to 24 hrs and use the HW time settings as before?

    Depending on the design of your plumbing, you may find that you will need to have the HW set 'on' at the times you want the central heating on for it to work anyway, but even if you do, at least the HW won't be on 24/7
     
  15. valmiki

    Joined:
    15 Apr 2010
    Messages:
    11
    Thanks Received:
    0
    Location:
    West Glamorgan
    Country:
    United Kingdom
    hi DP

    Interesting, the Danfoss controller looks full of features but is twice the price I paid for the Siemens, however I'll take a closer look just in case - if it looks worth it I may buy it and flog the Siemens one on fleabay.

    stem, this was one of the reasons why I asked my questions. There are two channels for HW and CH but on the programmer the CH 'forces' the HW to the same setting. For example, I can have HW and CH both on auto (timer) but if I change the CH to 24hrs it will also change the HW to 24hrs, if that makes sense? With the CH on 24hrs I can't change the HW to anything else.

    This was why I though initially that I'd have to adjust some wires at the boiler, but the bloke on the helpline was adamant that the HW on these boilers is on demand only - but if that's the case why would it have a separate channel for programming?

    Guess you guys know more about this than I do, I'm just glad that the bloke on the phone didn't want to check I was corgi-registered, etc.
     

Share This Page