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help wiring wire center for UFH

Discussion in 'Electrics UK' started by Zehroni, 14 Jul 2021.

  1. Zehroni

    Zehroni

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    I bought this wiring center on line for my 8 port under floor heating system. I had hope to see a designated wiring block for the boiler, pump and the zone valve. but this one do not and i am rather confused. based on the wiring sheet that came with it, see pic
    can someone help please
    1- where the boiler wires go?
    2- where the pump wires go?
    3- where the 5 wires of the zone valve go?
    4- do I need to link timer 1&2 everywhere in the Wiring center, i.e the main board and the individual zones?
     

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  2. ericmark

    ericmark

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    It tells you G1 is the volt free contacts for the boiler, and likely one pump is switched on with the boiler.

    How a boiler is wired varies depending on type of boiler, a oil boiler tends to be switched on/off, but a gas boiler tends to switch up/down, so with an oil boiler having a zone valve which is on/off is no problem, but with gas you need an analogue control.

    So rather than a zone valve one has a valve which can be slowly opened and closed, so in the main you have multi-pumps, the main pump pushes water through the boiler, then sub pumps circulates water around the floor, and each time the water temperature drops below the set figure set the valve opens a tad, and if too hot it closes a tad, so it can use water at say 70°C used for radiators to keep floor at 27°C, however if no radiators then no need for water at 70°C.

    So a central heating system is designed, this is why the people fitting the systems are called engineers, to work economically it takes clever design, so needs a degree to work out what is required, but a simply plumber can made it work, but possibly not very economically, and what is rather important is reaction speed, so rooms only heated when required, and only to the degree required, and under floor heating is really slow reacting, so it is normally combined with radiators. So the UFH is just a back ground heat.
     
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  4. Zehroni

    Zehroni

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    I am more confused than before now. the whole of the UF heating system was designed and sold to me by reputable suppliers. I followed their design and install it all. I am at the stage of fitting the hard wired wall thermostats and the wiring center head of installing new gas system boiler with tank. based on the wiring diagram:
    the 3 wires that are going from the Wiring center to the boiler will be connected as follows;
    brown to COM
    blue to NO
    G.Yellow to PE

    pump
    the UF pump
    the brown to L1
    the blue to N

    zone valve
    however the only one left to connect is the zone valve as it says should be connected this way;
    brown to L1 (which is the same terminal as the pump) , is that correct?
    blue to N
    grey to COM (which is the same terminal as the the boiler brow) is that correct?
    orange to NO (which is the same terminal as the the boiler blue) is that correct?
    G.Yellow to PE

    what do i need to do with timers blocks?
     
  5. ericmark

    ericmark

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    The first thing is floors take a long time to heat and cool, so great for an old peoples home where it wants heating 24/7, but for anyone who either wants it cooler at night, or goes out to work, the slow reaction time is a problem, I fitted an electric version in a wet room, and heat up time of floor was two hours, and to get room warm with a maximum floor temperature of 27°C your looking at setting the floor as back ground heating, radiators do main heating if your not running it 24/7.

    But it is reasonably easy to work out, how any heating works, the thermostat opens a valve, and the valve opening turns on boiler, but you need some one way valve so when boiler turns on with one valve opening it does not back feed and cause all the areas to heat together, so a standard two port valve has a micro switch built in to do this.

    So thermostat feeds brown and blue on the motorised valve, and the white and orange runs the boiler and main pump.

    However you also with most systems need a pump for each UFH set of pipe work, and there is only one micro switch in the two port valve, so we have a relay box which turns one set of micro switch contacts into two sets. One set runs local pump, other set runs main pump and boiler.

    So this upload_2021-7-15_12-34-53.png bit runs boiler and main pump. And this upload_2021-7-15_12-37-13.png bit runs the second pump and connects to thermostats and valves.

    So this upload_2021-7-15_12-40-18.png goes to the thermostat, line out to thermostat, neutral to thermostat and line in from thermostat. I would guess upload_2021-7-15_12-43-57.png has a link in it, as in the main today we use programmable thermostats rather than independent thermostat and timer.

    This upload_2021-7-15_12-46-33.png and this upload_2021-7-15_12-47-23.png needs some reading, I would expect it to supply some thing like this upload_2021-7-15_12-52-3.png but it does not make sense for both a two port motorised valve and an actuator to be used, as they basic do the same thing. So I would say only the brown and blue used with the motorised valve, and used instead of actuators.

    Or the upload_2021-7-15_12-59-52.png feeds a motorised valve for domestic hot water, and the under floor heating uses actuators. It says it feeds a pump for domestic hot water, which seems strange.

    But there are clearly more instructions, I am just looking at the instructions you have shown, and it does seem something is lacking, it may work with an oil boiler, but seems rather basic and although could be made to work with a modulating gas boiler it would not work in an efficient way, with gas we have timed on/off valves, but the thermostatic control needs to be analogue either analogue wall thermostats, as with OpenTherm or using thermostatic radiator valves which slowly open or close, they do not switch.

    Thermostats like EPH have two controls, it turns the valve on/off, but works as master and slaves to tell boiler what output is required.
     
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