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Honeywell CM927 Starting to Fail.

Discussion in 'Plumbing and Central Heating' started by Benny5, 4 May 2020.

  1. Benny5

    Benny5

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    I’ve got a four year old CM927 exhibiting sign of failure. (Display failing, but when I exert pressure on the PCB it then recovers for a while). I believe this is fairly common with some of these devices. Have been in touch with Honeywell and they have offered a £25 discount on the RRP of either of the following if purchased via plumbnation;
    T4R - Wireless Programmable Thermostat.
    T6R Smart Thermostat – Wireless.
    Installing either of these would not be straight forward. The location of the current unit is not close enough for hard wiring of one but by relocating I could possibly find power point to plug in the other.

    My question is should I stick with Honeywell and source a ‘like for like’ CM927 and risk more problems or source a battery only setup (similar to my current one) by a different manufacturer elsewhere.

    Thanks
    Benny.
     
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  3. CBW

    CBW

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    Hi Benny,

    What heating system do you have currently? I don’t understand, if you currently have a wireless room thermostat, then why can’t you use the existing receiver wiring? Honeywell (imo) have gone downhill since becoming part of another company. You may want to try another brand, or stick with Honeywell. A few on here recommend either of those.
     
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  4. Gasplumber

    Gasplumber

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    agreed Honeywell display issues on the cm’s is shocking.
    Hardwired is the future, or is it supposed to be the past haha
     
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  5. Benny5

    Benny5

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    Hi Chris.

    Thank you for your response.

    I have a Combi system; the CM927 part is located in the lounge with the receiver box BDR91 next to the boiler.

    I’m tempted to ‘nurse’ the existing one over the summer when a heating outage won’t matter. I’ve been able to get it back to life by applying pressure to PCB and display.

    Alternatively I could buy a ‘like for like’ CM927 (thermostat only) cost £100 and wait for the current one to fail. But will I have similar problems in another four years?

    The other option is to buy a T6R cost £110 plus fitting costs; receiver box has to be swapped.

    My OH is familiar with the existing one and may find managing the possible complexity of the T6R smart option too much.

    Thanks,

    Benny.
     
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  6. CBW

    CBW

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    Hi Benny,

    What I’m saying is basically the BDR receiver box can be swapped for another type, it’s just the wiring, likewise with the handset (cm927). You mentioned it would be difficult to hard wire (yes probably would). What seemed odd was plugging in? So you only need a single channel version, but you could even go for a Hive, Nest, if they’re your cup of tea, or any other wireless arrangement. There are lots on the market, and I’ve only experience of a select few.
     
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  7. Benny5

    Benny5

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    Hi Chris.

    Just to clarify the ‘plugging in’ comment. The T6R display/controller comes with a mains cable and plug.

    And on further investigation I realised my mistake on the T4R, I’ve just noticed the T4R display’s power source is similar to the CM927 i.e. batteries. That would just leave a changeover of the receiver box so for me perhaps it becomes a better option.

    I’m assuming the T4R would prove more reliable than the CM927 given that is has fewer mechanical (moving) parts.

    Thanks,

    Benny.
     
  8. CBW

    CBW

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    Hi Benny,

    I’ve no idea on reliability, as one product by the same company can differ. I wasn’t aware of any of them plugging in, so thanks for that. Perhaps the T4R maybe better, but as I said, you done have to stick with Honeywell.

    Chris.
     
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  9. SFK

    SFK

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  11. Benny5

    Benny5

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    Thanks for the pointer.

    It’s got me searching the internet and can see YouTube videos on how to fix the screen display issue. It appears to me that they suffer from ‘dry joint’ syndrome. By stripping them down, applying heat seems to resolve the issue, don’t know whether this is long or just a short term fix. These units appear to have an inherent weakness.

    I’m inclined to bite the bullet and replace mine now rather than possibly get caught out in middle of winter.

    Benny.
     
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  12. Benny5

    Benny5

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    Just a follow on from the above I’ve been looking at the wiring arrangements for a possible DIY change-out of the receiver CM927/BDR91 to the T4R.
    I’ve provided an image of the existing wiring also a copy of the wiring for the possible replacement.
    Anyone know if these are ‘like for like’ terminal change outs?

    Thanks Benny.

    Edit;Should have said the boiler is a Vaillant Combi.
     

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  13. CBW

    CBW

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    Hi Benny,

    Yes pretty much the same.

    Chris.
     
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  14. Benny5

    Benny5

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    Thanks Chris,

    What puzzled me a little was my wiring looked like the ‘Basic’ as opposed to the ‘Combi’ boiler arrangement for the T4R.

    Thanks Benny.
     
  15. Benny5

    Benny5

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    On the pursuit for a replacement for my existing CM927/BDR91, I have looked at the Honeywell T4R (£95) but also found a Wolseley Center device (Product code 340017) (£71), which appears to be a Honeywell device badged for Wolseley.
    The former comes with a one year warranty while the Center alternative has two. There is also a suggestion that the Center device can be ‘paired’ with the existing relay unit. Anyone know if this is the case, also, any views on the reliability of this alternative?

    Thanks Benny.
     
  16. lightning

    lightning

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    Why don’t you just fix the cm927 it takes about 10 mins to do
     
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  17. Benny5

    Benny5

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    Yes, from my original post I indicated I managed to get it back to life, however, I think this may be just a short-term fix and is likely to be repeated. Furthermore, I managed to get Honeywell to provide a discount, for a replacement, for the premature failure hence the decision to look at a replacement.

    Thanks Benny.
     
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