Replacement room thermostat and programmer for a Worcester 28CDi RSF Boiler

Discussion in 'Plumbers' Talk' started by MarkyFareham, Dec 2, 2013.

  1. MarkyFareham

    MarkyFareham New Member

    Hello, can anybody out there help me?
    My programmer on my Worcester 28CDI RSF boiler has the “ROOM STAT” red light constantly on which means that it is not getting a signal from the room thermostat or there is a fault in now the programmer is getting the signal. I replaced the batteries in the room thermostat but no joy.
    Looking at the programmer it seems I have three wires going from the programmer to the PCB. I am wondering if I can a) source a direct replacement online somewhere (if so where?) or b) source an alternative replacement which could either fit into the space of the old programmer or fit externally?
    Attached are pics of the connector and pages from the manual showing the connector and the current programmer/room thermostat. I am left wondering which wires do what if I don't get a direct replacement.
    The main remit is one room thermostat which wirelessly sends a signal to the boiler based on some programming information e.g. come on at certain time etc…
    Thanks in advance to anyone who can help.
    Thanks - Mark

    Attached Files:

  2. kiaora

    kiaora Member

    hi
    not familiar with this stat but some rf stats require to put the receiver/boiler in learn mode when changing the batteries!
    check out the instructions first
    regards
    peter
  3. MarkyFareham

    MarkyFareham New Member

    Hi Peter, I did try putting the programmer into learn mode when replacing the batteries and starting the room thermostat again. No joy for me. This all happened overnight when the programmer started ignoring the room thermostat and I noticed the red light was on permanantly on the programmer. I only then tried replacing the batteries on the room thermostat and pressing the two buttons on the programmer for it to go into learn mode but the red light remains on no matter what I do. I tried turning the boiler off and on but the lithium battery keeps the unit clock alive. I didn't know if I could take out the lithium battery from this unit for a full reset (and whether that would help or not). This is why I am starting to wonder if I can directly replace or wire up another programmer and room thermostat?
  4. kiaora

    kiaora Member

    hi
    its quite simple to connect a different programmer and stat, do you have the boiler installation instructions?
    regards
    peter
  5. MarkyFareham

    MarkyFareham New Member

    Hi Peter, attached is a much better picture of the only wires which go from the current programmer onto the main PCB of the CDi boiler. Also attached is the only reference to the connection for the programmer (but it doesn't seem to explicitly say what connector does what). Would you (or anybody out there) know what wire is doing what so that if I get a nice cheap alternative I can wire it in to work? Thanks for this. Mark P.S. I tried all kinds to try and get the programmer to accept a signal from the room stat last night (pressed the recommended buttons to go into learn more and pulled batteries from the room stat right next to it) but the red light remains stubbornly on so I am resigned to replacing the programmer/room stat

    Attached Files:

  6. MarkyFareham

    MarkyFareham New Member

    Hi Peter, I think I have figured something out as per the attached boil5.jpg. It looks like I have been concentrating on replacing the facia mounted programmer plugged into ST5 as per my last post. But there is a figure 13 in the attached boil5.jpg showing wiring for attaching an external programmer which should give me more options. Do you recommend an external programmer to fit to ST8 and then how would I wire it up according to fig 13 (there seems to be 3 options for wiring). Thanks! Mark

    Attached Files:

  7. kiaora

    kiaora Member

    Hi
    St8 is the live neutral and switch live, just remove the link, or any wires connected there, and run the wiring from there to your new programmer!
    Regards
    Peter
  8. kiaora

    kiaora Member

    Hi
    Also the 3 wiring options are for, clock only, stat only, or clock and stat,
    Just run a flex from there to your programmer of choice
    Regards
    peter
  9. MarkyFareham

    MarkyFareham New Member

    Excellent. Many thanks. Do you have a recommended programmer/wireless room stat for between £50 and £100? I see there are "volt free" "24v" and "230v" options around and not sure which one to choose. Does ST8 power the programmer or do I need to wire in separate power to the programmer? I guess the new programmer will be a clock and stat? If the instructions on the new programmer are good enough they should show output marked at Ns, Ls and Lr correct? Attached is a pic of ST8 which has the link I need to remove. Do I need to remove the facia programmer from ST5 for the new one to work or doesn't it matter (not receiving signal anyway). Thanks for all this Peter!!

    Attached Files:

  10. kiaora

    kiaora Member

    hi
    just been looking at the book.. it appears if you disconnect the s5 connector from the board, it should start up !, because you have the link still in.
    check it out first!
    peter
  11. MarkyFareham

    MarkyFareham New Member

    Hi Peter, I can still use the facia programmer plugged into ST5 (luckily) to switch on the central heating. The issue is that it is not accepting a signal from the room stat to do so. Therefore I have to manually press the top button on the programmer each time I want to fire up the central heating and then when I think it's hot enough I press that button again to turn it off. I have been looking around and it seems that new external progammers have different ways of being wired into the Ns, Ls and Lr of ST8 (230v or "volt" free?). I just want to make sure I get it right. Any advise here? Thanks Mark
  12. kiaora

    kiaora Member

    Hi
    Before we start, you need to make sure of a couple of things..
    If you remove the old programmer completely from the pcb.. Will the heating run, and then you can take the link out to prove all this chatting is correct and the link actually controls the heating.
    This is important, not to fit new programmer before it's establish that we have the correct solution.
    I don't know your skills, so I am trying to take one step at a time
    Regards
    Peter
  13. MarkyFareham

    MarkyFareham New Member

    Hi Peter, just to update you I fitted a new external programmer over the weekend (this one -
    http://www.heatingcontrolsonline.co.uk/siemens-rev24rf-7day-wireless-programmable-thermostat-p-531.html)
    and it works fine. I did test taking out the facia programmer from ST5 and like a plonker I left the link in for ST8 and it fired up (but wouldn't stop)! So after a panic and reset I wired up the new external programmer to ST8 and it is now controlling the central heating (the facia programmer is completely disconnected to from ST5). Job done. Thanks! Mark
  14. chickenrebel

    chickenrebel New Member

    @MarkyFareham...Hi Marky, I am having the same issue you listed above, with the same boiler, programmer and wireless thermostat control. Can I ask, for the new programmer you purchased, did this fit into the facia on the boiler, like the previous programmer?

    Also, did you connect the new programmer just to ST8, or did you also use the Ns, Ls, Lr connections, or a combination?

    Any advice would be appreciated,

    Thanks
  15. MarkyFareham

    MarkyFareham New Member

    Hi Chickenrebel, The siemens receiver/programmer in the link above is an external one (doesn't fit into the facia). It only needs to be wired into ST8. The guys a heatingcontrolsonline can give you the suggested wiring. The external receiver is just sitting by the boiler. I have had this running for a few months now and it works fine. As for the facia programmer I have left in in place with ST5 disconnected. It is effectively dead now with the siemens external receiver doing the job. Hope this helps..
  16. chickenrebel

    chickenrebel New Member

    Thanks Marky, much appreciated.

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