Nest Install....Please Help

Discussion in 'Home Automation' started by F02613040, 19 Aug 2018.

  1. F02613040

    F02613040

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    Hi all,

    I am moving into a new home and wanted to install the Nest. I looked at the wiring to the Drayton reciever which seems simple enough, also wiring from the Glow worm boiler.

    I have the Neutral and Live coming from a fused switch and then 1 and 3 coming from the boiler.

    My assumption is as follows,

    Connect the N from the switch to N on the link
    Connect the L from the switch to the L on the link
    Wrap the earth wire up from the switch or connect to the earth on the link

    Im not sure where to connect the current 1 and 3 to? Would it be the same 1 and 3 on the heatlink or do I need additional wiring?

    Any advice is much appreciated and thanks for responses in advance.
     

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  3. F02613040

    F02613040

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    Anyone?
     
  4. ericmark

    ericmark

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    [​IMG] Looking at this wiring diagram 1 and 3 go to 2 and 3 if nest used as an on/off thermostat. I did look at compatibility list and it seems your boiler is not on it.

    There is a reason why technicians working on central heating and ventilating systems are often called engineers, it is not just making heating work, it is making heating work well. Anyone with reasonable skill can fit EvoHome with OpenTherm, the systems does it all for you, but with the cheaper systems it takes more skill.

    I don't have that skill, but I do know it is required, I will try to explain, with a modulating boiler turning the flow through TRV down will cause boiler to modulate (turn down the flame) also a time clock can turn boiler off and on twice a day with not problem.

    But what happens to the boiler if turned on/off every 5 minutes? I don't know, but it must cause some stress, now a simple thermostat will turn on/off with quite a high hysteresis, [​IMG] which as the user we don't want, so smart thermostats turn the heating off/on before set point to reduce that wave form, this will control the heating better, but it can also have other unwanted effects, one extra stress on boiler, and two stop boiler modulating so in turn it can make the boiler run inefficiently. Also clearly any thermostat only controls the room it is in.

    Not saying we don't want a wall thermostat, the modulating boiler needs some thing to tell it to switch off on a warm day without needing to fire up and test return water temperature, but I do question using a thermostat which uses a mark/space ratio to reduce the hysteresis.

    I think Glow worm use MiGo modulating thermostats, as I have said I am no heating engineer, there are some very clever guys on this forum like "Stem" there are also some stick in the muds who have never updated skills, and the DIY guy like me who are still feeling there way around how central heating works.
     
  5. DIYnot Local

    DIYnot Local

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