Replacing CM67 - 2 wire stat/programmer with Hive single channel receiver

Discussion in 'Project Photos' started by fmchaos, Apr 26, 2023.

  1. fmchaos

    fmchaos New Member

    After any advice. Moved into a newish home last year. It has 2 zones for heating. 1 downstairs heating & 1 upstairs. Worcester system boiler. The downstairs heating & hot water we're controlled by a Honeywell ST9400C and separate wall stat. I have replaced the ST9400C with a Hive 2 channel receiver, stat & hub at router. Pretty easy to do & it's all working fine. (i already had the hive system in previous home, which only had 1 zone) I'm looking to add a single channel hive receiver & separate thermostat to control the upstairs heating (zone 2) That's currently controlled by a separate combined programmer/stat a Honeywell CM67.

    I have taken the cover off and it has only 2 wires connected to it. See picture. But the cable appears to have a 3rd core & a 4th core looped back. (presuming 3 core & earth) I know the hive receiver will need power.

    So I'm now presuming ill need to place single channel hive receiver near the main wiring junction box in the airing cupboard.

    In the airing cupboard there are 2 JBs, 1 large (Danfoss WC4B) & another marked `Honeywell' The 3 valves (Hot Water, upstairs CH & downstairs CH) all go into the Danfoss along with a cable from Hot Water tank. And 2 other cables come from the Honeywell JB. In the Honeywell JB there appears to be cables coming into the back of the box through the internal wall. Presuming these come from the downstairs programmer (now Hive 2 channel receiver / boiler) & the upstairs programmer/stat `CM67'?

    I have taken photos of the CM67 & both JBs.

    I know i need to supply new 1 channel Hive with mains power. Can pick that up in the main wiring box. But what & where do I connect from receiver to switch on/off upstairs heating? I can't figure out which is the connection from the `CM67'?

    I’ve looked at going for a smart 2 wire thermostat & just replace the CM67, Nest E / Gen 3 (rather not mix manufacturers & have to have another app etc) or a Hive SLT5.
    But ideally be nice to match up what I have with zone 1 downstairs & be able to have the wireless hive thermostat & be able to place it wherever we like.

    1st pic is the Honeywell JB. Next 2 are the Danfoss WC4B JB. Last 2 pics are the CM67.

    Appreciate any advice. Thanks.

    IMG_20230425_171623.jpg IMG_20230425_171042.jpg IMG_20230425_171311.jpg

    IMG_20230411_190346.jpg IMG_20230411_190351.jpg
     
  2. Mike83

    Mike83 Screwfix Select

    BC04EDF3-B8D1-444F-8BFE-E9ACF56945E5.jpeg In this picture you can see the 3 zone valve cables.
    You should be able to work out what zone valve you need by turning on the upstairs heating. Once the valve is identified (the lever will become loose) you need to locate its brown wire. This brown wire will link in with another wire from the existing stat. Remove this wire just now but keep the brown in place. Now run a wire from hive terminal 3 and put it in with this brown wire.
    All you would need to do is then give the hive a power supply which you mentioned. Then you would just link live & 1pm the hive.
    Once the hive is up and running we can look at removing the old stat cable from the system.
     
  3. fmchaos

    fmchaos New Member

    Hi,

    Thanks for the reply appreciated.
    The valves are marked so pretty sure which one it is. But I'll do the check suggested.
    Haven't bought the hive yet. Will probably sort over the weekend and report back. Thanks again.
     
  4. fmchaos

    fmchaos New Member

    Hi,
    Hive ordered from Screwfix. Been looking a bit closer & noticed there's a grey wire not connected in the smaller terminal box in airing cupboard (pic 2 - top to the right). Wondering if this could be the other end of the grey core looped back at the CM67? (pic 1). If so i presume i can use this as a neutral for the hive receiver and put the hive receiver in the same place as the CM67. I will bell it out over the weekend. Am i right in presuming i pick up neutral from one of the blue cores in that box? Also my boiler isn't assigned it's only circuit in the dist. board, so again i believe it's off the downstairs sockets? So i only need to isolate that MCB? (pic 1) Appreciate any thoughts. Capture.JPG IMG_20230425_171623.jpg IMG_20230411_190351.jpg )
     

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  5. Mike83

    Mike83 Screwfix Select

    If you’re happy with the receiver being on show then it will work if you find and wire in that neutral.
    You should have a main fused switch that isolates the heating system. Could be at the boiler or cylinder.
     
    ElecCEng likes this.
  6. fmchaos

    fmchaos New Member

    Hi. Gr8 thanks again for your quick reply. Ye on display is fine. Yes there's a main 'Boiler' switch under the cupboard that houses the boiler. I switched off there and the downstairs sockets when I fitted hive downstairs. I presumed the whole system was on same circuit but wanted to double check. I'll report back.
     
  7. fmchaos

    fmchaos New Member

    Hi. Think I'm all sorted. The grey wire wasn't from old stat so followed your advice. I've removed the black from stat. Capped and isolated and noted it was in 7. Gonna leave stat where it is for now. Batteries out. Presume that's OK?
    Receiver in airing cupboard which is probably better. Less chance of the wife feeling trigger happy.
    Thanks for your help. Much appreciated.
     

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