1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Hive multi zone install with combi boiler

Discussion in 'Plumbing and Central Heating' started by Malky23, 27 Jul 2019.

  1. Malky23

    Malky23

    Joined:
    27 Jul 2019
    Messages:
    1
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi everyone! I'm new here.

    Having some trouble installing Hive active heating in my new home.
    House is a new build from a few years ago and has 2 zones (upstairs and downstairs).
    I have an Ideal Logic Combi 35 boiler and upstairs and downstairs each have a battery powered programmable thermostat (Danfoss TP5000).
    I have a hive heating only set with the hub and a multizone kit, both are single channel receivers.

    My confusion is with the wiring of these. Behind the thermostats is some 3core with earth wire, with the black wire (with brown sheath) connected to '3 N/O' and the brown wire connected to '2 COM'. The grey and earth wires have just been cut and the ends folded out the way.

    I tried connecting the first hive receiver downstairs which I believe ive done correct as I followed the diagram from a similar post however when I switched the power back on for the heating, no lights came on to the receiver.

    My question is, do I perhaps need to install both receivers to get power? Or am I missing something. I don't want to go ahead with the other until I'm sure I have power to the first one. I'm slightly confused as Im not 100% certain where the 3core has come from/going to but im assuming it comes from the switched fused spur beside my boiler?

    Any help you guys can offer is much appreciated.

    Thanks!
     
  2. Sponsored Links
  3. ericmark

    ericmark

    Joined:
    27 Jan 2008
    Messages:
    16,749
    Thanks Received:
    1,522
    Location:
    Llanfair Caereinion, Nr Welshpool
    Country:
    United Kingdom
    Hive has 6 terminals, one unused so down to 5, Number 2 heating off N/C is also not used so down to 4, if 230 volt control then Line and Com can be connected together so down to 3, however no configuration can reduce it further, and you only have 2 wires, so unless that grey is connected to neutral your stumped.

    Nest e is battery powered so that would work, but not Hive or Nest Second or Third generation.

    I cut and pasted the boiler and added installation instructions to end and got this set of instructions the next was I went to find on this page and typed in opentherm and it took me to page 33 where it shows how connected. Since Hive is not OpenTherm I would say not correct selection, however you also say it is zoned, so there seems some thing wrong!

    The whole idea of a modern boiler is it can modulate, i.e. turn down, there are two ways to turn it down, one is return water temperature, the other is the ebus in your case OpenTherm. So your boiler has an output between 8 and 24.3 kW once below 8 it uses a mark/space ratio to further reduce output, so if using an on/off thermostat all this does is turn off the boiler once it is no longer required i.e. summer, so it is placed in a room normally kept cool, on ground floor, with no doors to outside, and no alternative form of heating, if such a room exists, and the zones are timed only no individual thermostat for each floor as you don't want to be switching the boiler off/on all the time.

    However the outdated rules want zones so often done in an out dated way, as would have been done before the modulating boiler came out. The old way was thermostat works a zone valve which in turn works the boiler.

    So the big question is how far to go correcting the inappropriate control? Likely best idea is get rid of zone valves and fit Tado or EvoHome so every room becomes its own zone and the thermostatic radiator valve (TRV) becomes a motorised valve by changing the head. So each valve tells the thermostat/hub if it needs heat and then that thermostat/hub tells the boiler how much output is required.

    However there are cheaper methods, for £10 you can get the cheapest electronic head, for £15 same head with blue tooth, around £37.50 you get wifi heads and as you pay more so the heads do more, the problem is with the cheap heads there is nothing to tell the boiler when to run, so as summer arrives it will start cycling and that will not stop until you manually turn it off.

    Each house is different, sun in bay windows can really heat up a room, clearly a wall thermostat in that room would turn off too early and rest of house would be cold, so in my house the thermostat is placed as central as it can be placed, and the rooms around it are all linked to it. So when I change temperature on thermostat, hall, dinning room, and living room TRV heads follow the setting. However upstairs I have cheap £15 TRV heads, not perfect but better than it was.

    In my case the actually location was selected because wires existed to power it, I needed two wires from thermostat to heat link to power thermostat and transmit data to heat link, one reason why I selected Nest. Had I not needed to also control hot water, could have used Nest e which is battery operated so wireless.

    In hind sight, and hind sight is easy, EvoHome or Tado would have been better, but arrived at that house with £194 worth of TRV heads and hub, which were designed to work with Nest, so did not make sense for me to change, had I got easy access to run new cables, Hive would have likely been best option now Hive do TRV heads for their system, but my boiler is not modulating, hence Hive would have worked well, I run on oil here.

    There are some silly boilers, Worcester Bosch have Wave for example, which only controls one room, why not a clue, so some times even with a modulating boiler with ability to use ebus because of type of ebus thermostat better to use return hot water to control it. Point is Hive working a zone valve which in turn works the boiler will work, there is no question about that, the question is will it work in an efficient manor? And normal reason for fitting the likes of Hive is to make the system more efficient.

    Theory is when the boiler modulates it reduces hysteresis and so more efficient, and when it turns off, it is already running at coolest point, so less energy lost out of the flue, however every boiler has a sweet point where it runs most efficient and if that point is when it's running flat out, then it may be switching off/on is more efficient than all the cleaver modulating of the boiler. It seems this changes make to make, so although theory sound, in practice what you have may work just as good.

    However it seems you have to find a neutral which may mean you have to modify your ideas, so better your aware of what can be done, I also had a triple and earth cable between controller and boiler, but found only two wires connected. So you may be lucky and the grey may be neutral and it may be 230 volt switching, but it needs some testing first.
     
  4. mrStat

    mrStat

    Joined:
    11 Mar 2017
    Messages:
    174
    Thanks Received:
    63
    Location:
    Hertfordshire
    Country:
    United Kingdom
    @Malky23: This pretty normal for a new build. Your existing thermostats are battery powered. If the grey is simply folded back, then it’s not likely that it is connected to a Neutral at the other end (This is not always the case so caution and a multimeter should be used). The wire has simply been put there for future proofing and to allow installation of mains powered stats. You will have to find the main heating system junction box, usually located next to two valves.... One valve will be controlling upstairs and one will be doing downstairs. Sometimes silver, sometimes white. But they will be attached to your heating pipework somewhere near your boiler or in a cupboard above the boiler.

    When you find your heating junction box, power off, open up and take a photo before you go any further, I advise you then post the photo on here for further help or, give up and get a pro in.

    Just to clarify; it is not likely that your 3 core+earth is going to the fused spur.

    Ultimately once found, you should be disconnecting the wires going to the existing stats to make them safe and installing the Hive receivers near these valves; the Hive receivers control the valves and the valves control the boiler (The receivers should not be mounted where the old thermostats were). The Hive stat backplates can then be used to cover the holes where the old stats used to be and the Hive stats can be clicked into place.
     
    Last edited: 27 Jul 2019
  5. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page