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Is it possible to replace Altech model ALTHC007 with The Nest Learning Thermostat (3rd gen)?

Discussion in 'Plumbing and Central Heating' started by Erboka, 5 May 2021.

  1. Erboka

    Erboka

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    Hi All,

    I am looking to replace my old thermostat Altech (model: ALTHC007) with The Nest 3rd gen. Is this possible? It is connected to a Worcester boiler. All details on the pictures, let me know if you need anything else.

    I have no electrical knowledge beside common sense :)

    Kind Regards,
    E
     

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  3. CBW

    CBW

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    It’s usually possible, the nest thermostat could be placed in place of existing thermostat and put the wires the other end into T1 and T2. Alter all wiring at wiring center into heatlink (to be placed at wiring center also).
     
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  4. Erboka

    Erboka

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    That's promising! I would need more detailed info as "common sense" does let help me understand your explanation :) Nest Help suggest that 120/130V is needed, but I see mine has 220/230V is that not a game over?
     
  5. CBW

    CBW

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    Americans use 120/130vac, so that’s why they suggest it. If your Nest is U.K. version, it’ll need a 230vac supply. You’ll need to be able to safe isolate the electrics. You’ll need some 3 core flex cable for the supply, and then you’ll also need to establish what type of heating and hot water system you have (s-plan, y-plan, w-plan, c-plan). Once we know this we can guide further.
     
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  6. Erboka

    Erboka

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    More good news :) Thank you! How do I know the heating and hot water system? Should I remove somehow the boiler's front panel?
     
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  8. CBW

    CBW

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    My apologies, it appears you have a combination boiler, in which you only need the heating side of it. Do you run a tap for hot water, or do you have a hot water cylinder?

    I was thrown with the dual channel programmer. Position the heat link near your combi, use 5 core heat resistant flex cable, and alter the wiring.
     
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  9. ianmcd

    ianmcd

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    Post a pic of the nest you have please
     
  10. Erboka

    Erboka

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    I do not have any additional/separate tanks for hot water.

    It's in the post at the moment, so cannot do it, however I can share a picture that was used by the online store. Also, I have taken a picture of inside the thermostat wire box. There are only those two wires, plus that taped grey (it has same brown, blue, yellow wires) and I have no idea where does it end.
     

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  11. ianmcd

    ianmcd

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    OK you have the correct one, the nest is wireless and connects to a receiver which is wired into the boiler, the actual nest thermostat does not get wired direct to the boiler, the nest uses a USB cable plugged into a mains plug, but you can use those existing wires to power the nest from T1 & T2 at the receiver, if using these you must also have an earth at the thermostat,the installation is not a DIY task as you have to remove the boiler combustion cover so have to be gas safe registered to do so, you would be better with the Nest E thermosta and you can fit this yourself and is very easy to do
     
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