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Changing a Thermostat stuck with wiring

Discussion in 'Plumbing and Central Heating' started by smon jones, 20 Jun 2019.

  1. smon jones

    smon jones

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    Hi I have a old Honey well Thermostat I would like to replace with a digital Thermostat but stuck with wiring. Please advise
    This is old Thermostat
    This is new Thermostat
    I wired them up the same as numbers but blew the 3AMp fuse in the boiler not good
    Old one is back on at moment
     
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  3. ianmcd

    ianmcd

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    you havent posted the pics
     
  4. smon jones

    smon jones

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    Uploaded pictures now i hope
     

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  5. smon jones

    smon jones

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    This is the new tbermostat
     

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  6. ianmcd

    ianmcd

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    Yellow from old stat to 1 in new stat
    Red from old stat to 2 in new stat
    Blue in old stat must be safely terminated as is not used in the new thermostat, I think you used the blue and thats what has blown the boiler fuse
     
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  7. SFK

    SFK

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    ..
     
  8. smon jones

    smon jones

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    On the old there is 3 wires and Earth. Red yellow and blue. Which colour goes to which number please
     
  9. ianmcd

    ianmcd

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    you are only using the red and yellow wires the earth and the neutral must be safely terminated, I have already posted what coulour goes to which number
     
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  11. smon jones

    smon jones

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    Thanks let me try that later.
     
  12. Me learning: Can I just ask, why would the wires change? I thought 1 on Honeywell (live) would go to live (1) on new stat and 3 from Honeywell (switched live) to 2 (switched) in new stat?
     
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  13. bernardgreen

    bernardgreen

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    There is a small advantage in putting the Load to the Common of a changeover switch and the Live to one of the contacts.

    If the Live is connected to Common then when heating is not required the unused terminal becomes Live.
     
  14. andytw

    andytw

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  15. ianmcd

    ianmcd

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    3 on the new stat is switched live for air conditioning, if you look closer you will see 2 has heat written on it and 3 has cool written on it, the new stat is a foreign make if it had been a new Honeywell then the numbers would probably have been the same, the numbers and colour of wires in heating controls seldom means anything, it is up to who wired it up
     
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  16. - yes I did see that and wondered what the cool bit was for. I was just to engrossed in the live being on a different number.
     
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  17. ianmcd

    ianmcd

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    The red wire doesnt mean that it is live
     
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