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Hive replacing existing Potterton EP3002 and separate Danfoss rx1 thermostat

Discussion in 'Electrics UK' started by CRich160, 12 Sep 2018.

  1. CRich160

    CRich160

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    Hi

    Recently moved and currently have a Potterton EP3002 programmer for hot water and central heating. Central heating works by having this constantly switched on as is ultimately controlled by a Danfoss RX1 wireless thermostat. Pictures attached. Whilst the Potterton has some redundant wires in there (terminals B and C) everything else looks like a standard s-plan configuration. My question is how do I bypass the RX1 as ultimately the Hive thermostat will now control this. Can I just add a wire in the RX1 to bypass the switch?
     

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  3. EFLImpudence

    EFLImpudence

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    Have you bought a single channel or two channel Hive?

    You could do what you say but it would then be a further bodge with programmer CH on permanently and thermostat redundant.
     
  4. CRich160

    CRich160

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    Hi

    Thanks for response - it’s a 2 channel hive so will replace the programmer but the CH will effectively get overridden by the Danfoss rx1. That’s why I want to bypass the Danfoss but not sure which wires I need to connect in the Danfoss receiver in the attached diagram?
     
  5. EFLImpudence

    EFLImpudence

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    Yes, but now your programmer and thermostat are both redundant.

    Your hive needs connecting to the boiler or wiring centre instead of the programmer and thermostat, not in addition to them.

    It needs rewiring properly.
     
  6. ericmark

    ericmark

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    Are you sure? I have been looking on the hive instructions and it does seem there is no hot water thermostat, Hive it seems will time when water is heated, but I can't see any thermostat. The only thermostat seems to be the room thermostat, which as far as I can see will not connect to the eTRV heads so rather useless anyway?
     
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  8. EFLImpudence

    EFLImpudence

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    OP already has the programmer CH time on permanent because he has a wireless Room thermostat which he now also wants to bypass.

    As he has an S-plan system the tank stat will (presumably) remain.


    I do not think it right to leave the present programmer connected with CH and DHW permanently on and room stat shorted to permanently calling when they can be disconnected.
     
  9. ericmark

    ericmark

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    The 5 core cable at the thermostat is not seen at the programmer, and it uses both NO and NC contacts which seems unusual. Also removing power from the base unit will cause the battery to fail premature so I would have expected the unit to be always powered, some where there must be another box, if there were only terminals 2 and 3 used then it would be just a case of finding other end of cable and linking brown to grey, but big question is why is that black wire there?

    I looked for a Hive wiring diagram, however all I could find seemed to miss out completely how the domestic hot water is wired, Nest gives a full wiring diagram on page 22, it shows both thermostats. Also Nest has volt free contacts and can be connected direct to the boiler eBUS if the boiler is OpenTherm, plus it can be linked to eTRV heads, it is a proper control system. It just seems Hive is cheap and nasty.

    However since the Nest circuit diagram for S Plan has the Line linked to the common terminals, one could follow nest plan and wire Hive the same way. Nest 3 = Hive 4 and Nest 6 = Hive 3, rest is the same.
     
  10. ban-all-sheds

    ban-all-sheds

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    Oooh, shiny thing.
     
  11. ericmark

    ericmark

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    Likely correct, I tried the automated function of my eTRV's and the response time is too slow, to be able to automatically heat the rooms as we approach home it would need to be set at around 150 miles radius and it is so rare we are that far away it would hardly every work. So although we have the option of using geofencing, it is not used, as to manually altering temperature, I simply forget, so pointless.

    Of course it may seem to work, but unless your continually monitoring how do you know? But whole idea with modern central heating is to modulate boiler, not switch if off/on, by modulating the flow through radiators which in turn modulates boiler output the temperature is maintained at the level set with no hysteresis. There are two methods used to do this. One is the TRV the other is the modulating wall thermostat the latter must connect to eBUS of boiler.

    There is a place for the simple on/off thermostat, this unit stops boiler cycling as the weather gets warmer, the important feature is you DON'T want any anti-hysteresis software built into the thermostat as whole idea is to reduce cycling not to increase it.

    A wall thermostat can control a whole house if either the house is open plan, or using hot air central heating, or it has multi sensors one for each main room. Which means in real terms hive will only work correctly in a very small proportion of British houses. For Hive to work, boiler must be old, pre-modulating type, and control must be 230 volt, so it would not work in any of my houses, as either 24 volt control system, or modulating boiler.

    So yes in the main, it just looks good.
     
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