thank you Simon, I do understand the s plan, I will make sure I fully understand it all before I leave the first fix, I realise you lot think I’m an idiot that’s fine but we all have to start somewhere we weren’t born with this knowledge perhaps I’m not the cleverest person maybe it’ll take me a while to fully grasp iTs mainly Me being over the top and worried about missing something now and it costing me later. I’ve done lots of s plan system when there is only one wiring centre but this has two an it’s connecting the two and which cabling to run now at this stage which I’m slightly confused on.Are you familiar with the wiring for an S-Plan system ? If not, time to go and do some swotting upYou'll find loads of tutorials online.
In a standard S-Plan, regardless of how many zone valves, you have a switch in each zone valves that is closed when the valve is open. You wire these in parallel so that when any of the valves is open, the control circuit sees a closed switch. You connect this combination across the demand terminals of the boiler - so boiler runs whenever any of the zone valves is open (and hence it's switch is closed).
If you still aren't sure, grab two or three ordinary light switches, set yourself up a standard "loop at rose" light setup, but instead of having one switch, continue off to several - just T&E, brown-in & brown-out in one terminal, blue(sleeved brown)-in & blue(sleeved brown)-out in the other terminal till you reach the last switch. Then play with the switches - if any of the switches is on, then the light is on; to have the light off then you must have all switches off. Understand this and you understand the basics of S-Plan
Many boilers simply require a switched live - so one side of the control switch is connected to live, and when there's a demand, the boiler powers up. Most fo the S-Plan diagrams you will find have either the grey or orange wires connected to live for this reason.
WARNING However, there are many boilers (both new and old, we have an old one here) where this is not the case, if you connect live to the control terminals then you will just blow up the control board. For these you MUST use volt-free switching (i.e. no part of the switch circuit is connected to the mains) across the control terminals. Get this wrong and the cost of replacing the control board will seriously dent your profits
So now you understand S-Plan - just connect up the grey wires from all the zone valves together, connect up all the orange wires together, connect these two across the boiler demand terminals or between live and the boiler control terminal depending on the boiler.
What about that UFH manifold ? It has a pair of terminals that are closed (by an internal relay) whenever any of the zone stats is calling for heat. Treat that pair of terminals like the grey & orange wires in a standard 2 port zone valve head. So you parallel those terminals with the grey & orange wires from the zone valves controlling the hot water and rad circuits.
If the plumber is fitting a zone valve by the UFH manifold (which is not required in most cases), then the UFH manifold will control the valve, and you'll use the switch in the valve head (grey & orange wires) to control the boiler - completely standard S-Plan setup.
As above, some boilers need volt-free switching - so run two cores for the switching function. If the boiler takes a switched live, then you could get away with just one (so a single 3C&E rather than 2off T&E) - but if the boiler gets changed in the future and needs volt-free then your ears will be burning if they are a core short in the connecting cables.
And the whole system should run from one supply*, so take the power (L&N) for the UFH manifold from the main wiring centre. So between main WC and UFH WC, run 2off (one for power, one for control) T&E or 4C+E - one core may be un-needed now, but it is completely forseeable that it could be needed in the future.
* For a domestic install then there are few valid reasons for not running the whole heating system from one supply. But I believe it's technically valid provided you only use volt-free contacts to pass control signals between different parts of the system and there are suitable "multiple supplies" warning labels. As you are doing first-fix and can install the cable needed, there's really no excuse not to use just one supply.
BTW - is there a programmer for the downstairs heating, or is time control part of the stats ? If time control is to be from a central (e.g. 3 way) time switch, then you'll need another core to take the timer "on" signal from the main WC to the UFH WC.
Now, your homework is to sketch this all out (don't worry too much about the detail of the UFH stats and actuators), then present for our amusement, err sorry, constructive review.
The boiler is in garage and ufh manifold is in down stairs cupboard and the upstairs airing cupboard has the rest of it.
The stats have built in programmers, the ufh manifold doesn’t have a built in valve it’s external supplied by plumbers.
I’ll get it anyway..
Thank for your constructive help
