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Drayton UP1 to Nest help!!!

Discussion in 'Electrics UK' started by Pwizzle93, 27 Aug 2021.

  1. Pwizzle93

    Pwizzle93

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    Hi Guys,

    can someone help me please? I’m trying to install a nest thermostat in replacement for a British Gas (Drayton) UP1

    I haven’t got a clue where any of the wires go :(

    Any help will be appreciated
     

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  3. ericmark

    ericmark

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    Location:
    Llanfair Caereinion, Nr Welshpool
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    N to N
    L to L plus 2 and 5
    1 to a junction block, using the wiring diagram it would be 4 however there is no terminal with UP1 so seems likely just used as a junction.
    2 to a junction block, using the wiring diagram it would be 2 however there is no terminal with UP1 so seems likely just used as a junction.
    3 to 6
    4 to 3
    T1 and T2 go to thermostat unless being powered using a cradle and USB.
    OT1 and OT2 not used.

    It does depend on the boiler, many gas boilers modulate, that means turn down, it makes them run more efficiently, oil simply switch on/off, there are two ways to control the modulation of the boiler, one with return water temperature, the other electrical, connecting to the boiler ebus, Nest is designed to connect to boiler ebus using opentherm, Hive however is designed to connect the TRV (thermostatic radiator valve) heads and use the return water temperature.

    Most other smart thermostats can do either, Hive and Nest are the odd ones out, Nest is claimed to have a better algorithm, but since it will not connect to TRV heads or run as master/slave (EPH does that) it is rather limited as to when it does a good job.

    Evohome (Honeywell) and Wiser (Drayton) have add on modulates for opentherm, although not possible with DHW heating, and they connect to the TRV heads. EPH is designed for when heating is zoned using zone valves rather then TRV heads.

    They will all work, and they will all control the heating likely better than the original, but some will be more economical to others, with any boiler when it switches off any heat in the boiler is loss up the flue, so idea is to have boiler as cool as possible before switching off, so less heat loss up the flue, and also to switch off as little as possible, better if boiler turns down rather than off, since then it can gain the latent heat.

    So main control is the TRV, this allows every room to be independent, however there is a flaw, the TRV can never turn the boiler fully off, it would cycle on/off all summer long, so we still need a wall thermostat to turn off the boiler, either linked to TRV, or set to compliment the TRV, so with Nest you have to set TRV head with same program as wall thermostat, but it has a problem, the algorithms alter the Nest program to suit your life style, but it does not any more relay that information to the TRV heads, it did, it did work with Energenie MiHome TRV heads, but the support has been removed, so in real terms unless using hot air central heating Nest is now very poor.
     
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  4. CBW

    CBW

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    It looks like you may have a y-plan system. Also Nest doesn’t connect to eBus on boilers.
     
  5. ericmark

    ericmark

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    If you look upload_2021-8-28_4-5-40.png terminals 1 and 2 do not connect to pins on the programmer/thermostat. So you would need some terminal strip for those wires, Also to get those wires into Nest one would be stuck for room. I ended up with a junction box under the Nest heat link.

    Nest does connect to ebus on boilers using opentherm using terminals OT1 and OT2 however not sure if you can use motorised valves and opentherm? I know you can with EPH controls but not with Drayton Wiser, but depends on the boiler, Bosch do not seem to allow use of opentherm.

    Y plan need DHW off terminal and since not connected unlikely it is a Y plan.
     
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  6. CBW

    CBW

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    Hadn’t noticed those terminals missing :oops:
     
  7. AndyPRK

    AndyPRK

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    Yea. Eric was really on the ball with this one!
     
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