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Wireless room thermostat wiring

Discussion in 'Plumbing and Central Heating' started by MSP1, 2 Jan 2013.

  1. MSP1

    MSP1

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    Hi All,

    I am trying to figure out the correct wiring for a Horstmann wireless thermostat that I have been too chicken to attempt for over a year now!

    I have mapped the wiring in my junction box and attach a wiring diagram. Forgive the schoolboy approach with graphics, I have no knowledge of how to correctly create an electrical wiring diagram.


    I also took the front off the control unit (Drayton LP722) and noted the connections as Neutral and Live in N & L as expected, Green/Yellow in 1 (HW Off), Grey in 3 (HW On) and Black in 4 (CH On). These are indicated on the diagram alongside the control unit picture.

    The wireless thermostat receiver has L, N, SL on and SL Off. It suggests in the installation guide that SL off is not normally used. So, working from the diagram, I assume I need to attach Live and Neutral between the receiver and connector block at 7 and 2 respectively.

    Where then should I connect the SL on? If using three core and earth with yellow for example, does the current black wire from the LP722 (CH on) become obsolete, with the new thermostat controlling it instead via the yellow? Or does the current black remain in place and get joined by the SL on from the thermostat? Confused obviously!

    Many thanks for any help.
     
  2. doitall

    doitall

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    Looking at the drawing I think the next stop should be a sparky.
     
  3. Andygasman2010

    Andygasman2010

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    That diagram is too crowded and small I'm afraid. Next time omit the N and E wires for clarity.

    So you don't have a room stat at all at the minute?

    Mount the wireless receiver next to the programmer if you can.

    Take the L-N-E from it into the receiver.

    The CH-ON terminal of the programmer should then be connected to the COMMON terminal of the receiver.

    The ON terminal on the receiver should then be connected to the spare wire you've just removed from the CH-ON wire in the programmer (this feeds the white wire of the Mid-pos valve.

    Are you sure your wireless stat isn't a programmer too?
     
  4. D_Hailsham

    D_Hailsham

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    Is it a plain thermostat or a programmable stat?
     
  5. doitall

    doitall

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    The 2 wires in 9 are the switching pair (COM-ON) but the rest don't look right.

    5 is definitely wrong.

    Perhaps some information, make/models etc.
     
  6. MSP1

    MSP1

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  7. MSP1

    MSP1

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    Glowworm Ultracom 24hxi condensing boiler in airing cupboard with HW cylinder
    Drayton LP722 control unit
    Honeywell 3 way MV
    Honeywell cylinder thermostat
     
  8. MSP1

    MSP1

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    Correct, currently just radiator thermostats
     
  9. doitall

    doitall

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    So it should look like this.

    It looks as though the pump is wired back to the boiler in you sketch which is ok.

    The wires in terminals 4-5 are your 9.
     
  10. MSP1

    MSP1

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    Hi Andy...thanks for the info. Can I just ask a question please? I include a link to the thermostats installation guide.

    Installation guide

    If you look at page 9 it shows wiring for 230v and volt free applications. I have no idea if I can use the volt free or not, the LP722 says it has volt free contacts but I am not clear what that really means and whether that translates to being able to use the volt free example or not!

    So, If using the 230 volt application, I would take the N & L feed from the programmer as you say and also disconnect the CH On from within the programmer and connect directly to the SL (On) connector in the receiver.

    Am I right in thinking that the receiver would then have a permanent live from the programmer and as such "The CH-ON terminal of the programmer should then be connected to the COMMON terminal of the receiver. " would then be unnecessary? This would need to be done in volt free application though.

    Hope that makes sense, just wanted to check my own understanding, hope it doesn't read as though I am questioning your knowledge!

    Thanks again.
     
  11. Andygasman2010

    Andygasman2010

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    The advice in my first post is based on it being a room stat only, and not a programmable stat. So forget the reference to "common"

    230v and volt free is just the switch. It'll still need 230v to work so you can disregard the reference to "volt free" because you have 230v.
     
  12. Andygasman2010

    Andygasman2010

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    No. SL on is the feed to the white wire in the Mid-Pos valve. This is the wire that's currently connected to CH-ON in your programmer.

    If you mount it next to the programmer it's a simple job.

    Permanent LNE are straight forward. Now remove the wire from CH-ON in your programmer and connect it to "heat-on (SL-on) in the reciever.
     
  13. MSP1

    MSP1

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    Thanks all for the advice
     
  14. D_Hailsham

    D_Hailsham

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    That's confusing! There are two wires on terminal 9: one from the programmer; the other (white) from the motorized valve.

    A better way is as follows:

    Connect receiver to L , N and E as in the 230V diagram (leave link in place).
    Disconnect the white wire from 9 and connect it to 4.
    Connect a wire from receiver SL ON to terminal 4.

    The CH side of the original programmer has now been bypassed.
     
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  15. MSP1

    MSP1

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    Just to check for peace of mind, there is no earth connector on the thermostat receiver, just SL off, SL on, L and N, and a second L connected via the jump wire.

    I'm not missing something important with earthing am I?
     
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