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Honeywell to Nest replacement can you help?

Discussion in 'Plumbing and Central Heating' started by Diggsydiggsy, 27 Jan 2017.

  1. Diggsydiggsy

    Diggsydiggsy

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    Hi all,

    I'm installing a new Nest heating and hot water thermostat and I'm trying to identify the 'call-for-heat', 'common' and 'satisfied' wires in my existing Honeywell ST9100A hot water control so I can switch them to the Nest.

    Can anyone help please?

    Many thanks!!
     
  2. Echo the husky

    Echo the husky

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    The ST9100A is a 1 channel programmer, what currently controls your heating times?
     
  3. Diggsydiggsy

    Diggsydiggsy

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    Hey Husky, thanks for getting back so quickly. We actually use it to time our hot water.

    To ensure we're both talking about the same bit of kit here it is...

    https://www.plumbnation.co.uk/site/honeywell-st9100a-1-day-single-channel-programmer/

    We have a separate wireless Honeywell controller for our central heating.

    I'm hoping i can simply remove the wires out of the st9100a and put them in the Nest 3.

    Is it that simple and if so would you be so kind as to advise which go where please?

    I've seen previous posts so i know how to wire up the central heating side of nest.

    Cheers mate,

    Graham
     
  4. Echo the husky

    Echo the husky

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    well for just the hot water:
    old new
    1-5
    2-4
    4-6
     
    Last edited: 30 Jan 2017
  5. Diggsydiggsy

    Diggsydiggsy

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    Thanks Husk.
     
  6. Diggsydiggsy

    Diggsydiggsy

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    Hi husky,

    This is what the wiring looks like in my hot water boiler thermostat. There's no wire in 2 and the 1 goes into live. Not what I expected!

    Are you able to advise?

    Thanks again!
     
  7. Diggsydiggsy

    Diggsydiggsy

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  8. Echo the husky

    Echo the husky

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    That's not a thermostat, it's a timeclock.

    Ignore terminal 2 then, it's only used with some systems and keep the link the same. The rest is the same. The receiver will need to be connected by the wiring center where all the wiring connects back to, the other end of the cable in the photo will be disconnected and the wiring to the timeclock in the photo will not be used any more. I assume you have already installed the nest at the wiring centre to control the heating?
     
  9. Diggsydiggsy

    Diggsydiggsy

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    Thanks for getting back so quick! So the old 4 goes to 6 in the Nest? Is that the only connection I need to make in my Nest heat link. Leave the other hot water terminal empty? I've not touched the CH yet as I want to do it all in one go.

    Thanks again...I'll post/email you a beer ;)
     
  10. Echo the husky

    Echo the husky

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    You need a link from L to 5 as you did before.
     
  11. Diggsydiggsy

    Diggsydiggsy

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    ...I've got you

    • old 4 to new 6
    • then a short wire from the Nest L terminal to the Nest 5 terminal
    Do you have a husky btw....beautiful animals!
     
  12. Echo the husky

    Echo the husky

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    That's it.

    And sadly no real husky here, I work far too many hours to be able to look after animals.
     
  13. Diggsydiggsy

    Diggsydiggsy

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    Oh well. There's always retirement! Thanks for your kind help.
     
  14. HootingOwl

    HootingOwl

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    Why not hit the thanks button then? :)
     
    • Thanks Thanks x 1
  15. Diggsydiggsy

    Diggsydiggsy

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    Done! Muchas Gracias
     
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