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General: Underfloor heating wiring centres

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1 to 13 of 13

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    Hi,

    Apologies if this question has been asked before but I have googled it and searched on here and couldn't find an answer.

    I can't figure out how the wiring centre works. We would need a 12 port manifold but I can't find a wiring centre that covers more than 8 zones. Do I have to buy 2 wiring centres or have I misunderstood how they work?

    Also, if I decide to link certain rooms, such as the four bedrooms and landing on the top floor, can I install a single thermostat on the top landing and link 5 zones to one connection on the wiring centre?

    Cheers,
    POS
    • CommentAuthorcjard
    • CommentTimeJan 27th 2016 edited
     
    You don't normally have that many zones, or you buy more wiring centres. You can connect multiple actuators to one zone

    Example:

    In my downstairs I have 4 zones, and the manifold is a 12 port. For my lounge there are 3 loops of pipe but the lounge is only one zone. I will connect 1 thermostat to zone 1's thermostat connector. I will connect 3 actuators to the zone 1 connector (literally I will put 2 live wires in one of the screw holes marked L and one live in the other screw hole marked L so 3 actuators end up linked in parallel to the one connector block marked for zone 1)


    If you genuinely do have 12 stats and 12 zones and 12 ports and 12 actuators, you'll need an 8 port wiring centre and a 4 port wiring centre. I've got two 12 port manifolds - one for each floor, and a 4 zone centre for the downstairs (the floor has 4 zones), and an 8 zone centre for the upstairs (the upstairs has 6 zones).

    In summary, I have 10 thermostats, 10 zones, an 8 and a 4 wiring centres and 24 actuators/ports across 2 manifolds. No zone requires more than 4 ports of a manifold which is fortunate because heatmiser tell me that one can only connect 4 actuators to a zone connector block before the block is physically too small to accommodate any more wires, and I'd have to use a relay. I'd probably chance my arm to start and wire in another junction block to put 2 actuator wires down to 1 before it went into the zone connector
    • CommentAuthorringi
    • CommentTimeJan 27th 2016
     
    Depending on the type of thermostat you can also connect more then one "zone" of the wireing center to the same thermostat, so as to run more actuators.

    actuators use power, as there is a limited to how much power the wiring center can give out for each of its zones. Go about that limit and you may see spoke...
  4.  
    That's exactly what I needed to know, thanks guys. :)
  5.  
    I have an unused danfoss wiring centre you might be interested in?
    • CommentAuthorCWatters
    • CommentTimeJan 29th 2016 edited
     
    One of the things a wiring centre usually does is produce a Boiler Enable or BE signal. This is the logical OR of all the thermostats so if any call for heat the BE signal is active. It has some circuitry inside to do that. You can't just wire the stats together to produce BE because separate outputs are needed to control the individual valves.
    • CommentAuthorEd Davies
    • CommentTimeJan 29th 2016
     
    But presumably you can parallel up the BE outputs of two wiring centres to drive one boiler? (Assuming the whole lot's driven off one MCB (and hence one phase).)
    • CommentAuthorcjard
    • CommentTimeJan 30th 2016
     
    Here's a good moment I think to ask a question that it's raised in my mind..

    In my own house I have 2 12 port manifolds, each serving one floor. Once upon a time I was leaning toward a boiler so the manifolds have a thermostatic mixing valve and pump and on the actual manifold

    Now, I'm looking at an ASHP, so some elements of that may become effectively redundant. If the manifolds were pulling warm water out of a UVC or TS half way up (let's say) then I could still set the tmv on the manifold to the temp I wanted to run the floor at (could be advantageous as the two floors have different construction and the timber first floor may need a bit warmer than slab) but is there any point to the boiler enable?

    I'm presuming that the water tank itself will have gadgetry to know when it's going cold, and will demand heat, so the BE of the wiring centre may be unusued. Further, does it need a wiring centre at all? Or could the stats just directly control multiple actuators? I don't think they're poroportional actuators, they just open and close over a certain time period depending on the state of the switched live

    The pump is, I believe, an intelligent one that is constant flow or constant pressure. I presume if I set it in constant pressure mode it will ramp up and down as actuators open and close, in order to maintain a steady pressure.. Not sure if the same effect is achieved with constant flow.. So should I be operating it in constant flow or constant pressure mode?
    • CommentAuthorEd Davies
    • CommentTimeJan 30th 2016
     
    WTF is a UVC?

    None of https://en.wikipedia.org/wiki/UVC these seem likely.
  10.  
    Cjard

    Do you even need the actuators and thermostats? If you're well insulated you could just take the "run continuously at a few degrees above target room temperature" approach.
    • CommentAuthorcjard
    • CommentTimeJan 30th 2016 edited
     
    Ed, unvented cylinder.. Sorry.

    Simon, genuinely no idea. It may be possible to just run the whole lot as you say, or I may need the control. Opinions seem to vary wildly on what the thermal performance of my place will be, it's relatively well insulated with walls around 0.12, but there is a lot of glazing which surely raises the U. perhaps I should leave it all boxed up for max resale value and try running the heating without the controls..
    • CommentAuthorCWatters
    • CommentTimeJan 30th 2016
     
    <blockquote><cite>Posted By: Ed Davies</cite>But presumably you can parallel up the BE outputs of two wiring centres to drive one boiler? (Assuming the whole lot's driven off one MCB (and hence one phase).)</blockquote>

    Probably but check with the maker of the wiring centre. I suppose with some you might just connect them together, others might have a "BE in" and "BE out" to allow them to be daisy chained.
  13.  
    <blockquote><cite>Posted By: cjard</cite>Ed, unvented cylinder.. Sorry.

    Simon, genuinely no idea. It may be possible to just run the whole lot as you say, or I may need the control. Opinions seem to vary wildly on what the thermal performance of my place will be, it's relatively well insulated with walls around 0.12, but there is a lot of glazing which surely raises the U. perhaps I should leave it all boxed up for max resale value and try running the heating without the controls..</blockquote>


    My conclusion was that inividual room stats are poorly suited to UFH heating and likely to lead to swings in temperatures - the reaction time of the floor means it difficult to avoid under and overheating. Switching off individual rooms in a highly insulated house offers marginal benefits (and you can either do it manually at the manifold or rig simple room switches to manifold valves if you want to.)

    Our place has a lot of glass - oversized Windows, a glass wall in the living room and kitchen, large structural glass roof lights to kitchen and hall - and single zone seems to be working well. The key thing is that with low enough flow temperature it's largely self regulating. This winter isn't really giving a good test as it has been so warm (though we've had a few cold snaps). My Internal temp target is 20C and Variation is less than 1C within each room (Ie low 19.5 high 20.5)

    The hallway feels cooler but with the balance of glass to floor that's not surprising (I think you feel the cooler glass rather than air temp). The top floor bathroom is dropping to 18C but I always knew I might need a top up source in there.

    I currently have the floor in our bedroom turned off and it seems stable at 19C and the entire system shuts down between 2200 and 0430

    It looks like you can buy stand alone weather compensation controls -
    http://www.kanmor.com/where-to-buy.html

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