Heating system wiring...

[Peter1891]

Evening chaps,
On a new build this week first fixing, the heating system is giving me a headache,
Downstairs has wet UFH with a thermostat in every room (7 in total) I have the omnie stats and wiring centre which is fine with but upstairs is all rads with only one stat in the hall upstairs.
Also there is a separate circuit for wet towel rads which will need a separate programmer so they can come on in the summer.
How am I best to wire this all this?
the UFH manifold is in a cupboard downstairs the boiler is in the garage and there’s an airing cupboard upstairs.

 

[ETradesmen]

Evening chaps,
On a new build this week first fixing, the heating system is giving me a headache,
Downstairs has wet UFH with a thermostat in every room (7 in total) I have the omnie stats and wiring centre which is fine with but upstairs is all rads with only one stat in the hall upstairs.
Also there is a separate circuit for wet towel rads which will need a separate programmer so they can come on in the summer.
How am I best to wire this all this?
the UFH manifold is in a cupboard downstairs the boiler is in the garage and there’s an airing cupboard upstairs.

Hi Peter, best way is to not think about it all in one go!

I’d personally wire all the U/H programmers back to the manifold and then take a 3 core and earth (run two just to be safe) from the manifold to the wiring center. I’m assuming the water tank is by the boiler which means the wiring center / zone valves will be there too? As for the stat Doing the upstairs rads, that’ll go back to the wiring center too..

 

[Peter1891]

Hi Peter, best way is to not think about it all in one go!

I’d personally wire all the U/H programmers back to the manifold and then take a 3 core and earth (run two just to be safe) from the manifold to the wiring center. I’m assuming the water tank is by the boiler which means the wiring center / zone valves will be there too? As for the stat Doing the upstairs rads, that’ll go back to the wiring center too..

Hi mate
Thanks for a quick reply,
I’m still confused sorry! Long day.
The ufh manifold is located under the stairs in a cupboard I was going to put the wiring centre there and take all the stats to it in 3 core flex as there’s live in, SL out and neutral on the stats.
The programmer i was also going to put there with the wiring centre.
It’s the airing cupboard and the rads upstairs I was unsure off. Would I not have separate programmers for the towel rads and mains rads for upstairs in the airing cupboard as that’s where the plumbers valves will go and my immersion spur etc. I probably need to sleep and tackle it tomo as I’m too tired to think clearly now but any help is appreciated chaps thanks

 

[James]

draw it out before you put any cables anywhere.

if you cant picture it in your head, do a wiring diagram and follow it to the letter.

afterwards, fold it up and leave it in an obvious position to any following engineer.

 

[ETradesmen]

Does this help?

 

[123]

Hi mate
Thanks for a quick reply,
I’m still confused sorry! Long day.
The ufh manifold is located under the stairs in a cupboard I was going to put the wiring centre there and take all the stats to it in 3 core flex as there’s live in, SL out and neutral on the stats.
The programmer i was also going to put there with the wiring centre.
It’s the airing cupboard and the rads upstairs I was unsure off. Would I not have separate programmers for the towel rads and mains rads for upstairs in the airing cupboard as that’s where the plumbers valves will go and my immersion spur etc. I probably need to sleep and tackle it tomo as I’m too tired to think clearly now but any help is appreciated chaps thanks

Do your stats not need a cpc, even just to the back box? Would be far better in PVC/PVC 3 core & earth. Most common 3 core flex is Brown, Blue, Green Yellow so wouldn't be suitable.

Also you need to speak to the plumber to see where they are going to put their valves and any other equipment that will require wiring. Pumps for instance aren't always local to the boiler.

 

[Peter1891]

Does this help?

Thank you so much very kind! ??
[automerge]1592853144[/automerge]

Do your stats not need a cpc, even just to the back box? Would be far better in PVC/PVC 3 core & earth. Most common 3 core flex is Brown, Blue, Green Yellow so wouldn't be suitable.

Also you need to speak to the plumber to see where they are going to put their valves and any other equipment that will require wiring. Pumps for instance aren't always local to the boiler.

It’s a plastic stat an I’m going into a drywall back box so I was going to sleeve the earth brown on the flex but I’ll likely use 3 core and earth now after having a think and just wago the earth each end
[automerge]1592856633[/automerge]

Does this help?

Thanks for the pic mate, yes the UF valve is located by the manifold itself so Presumably I’ll extend the 5 core back to the wiring centre for that?

 

[ETradesmen]

Thank you so much very kind! ??
[automerge]1592853144[/automerge]

It’s a plastic stat an I’m going into a drywall back box so I was going to sleeve the earth brown on the flex but I’ll likely use 3 core and earth now after having a think and just wago the earth each end
[automerge]1592856633[/automerge]

Thanks for the pic mate, yes the UF valve is located by the manifold itself so Presumably I’ll extend the 5 core back to the wiring centre for that?

If the valve is by the manifold you only need a 3 core and earth back from the manifold to the main wiring center. The UF manifold diagram will show you how to incoropatre the zone valve within it.

Also, regardless of dry fix boxes being plastic the stat cable itself still needs a CPC if it’s 230v regardless as this protects anyone who could potentially penetrate it. If the stats are 12v dc you can wire them in either CAT5/6 or even alarm cable.

Please note the cables marked up 3 core in my drawing are 3 core and earth.

 

[Peter1891]

If the valve is by the manifold you only need a 3 core and earth back from the manifold to the main wiring center. The UF manifold diagram will show you how to incoropatre the zone valve within it.

Also, regardless of dry fix boxes being plastic the stat cable itself still needs a CPC if it’s 230v regardless as this protects anyone who could potentially penetrate it. If the stats are 12v dc you can wire them in either CAT5/6 or even alarm cable.

Please note the cables marked up 3 core in my drawing are 3 core and earth.

Hi, ok thank you here’s a pic of the stats and wiring centre.

 

[ETradesmen]

Hi, ok thank you here’s a pic of the stats and wiring centre.View attachment 58982

Says 230v stats only. The cables to these need to have CPC’s, this is fairly basic knowledge!
Good luck

 

[Simon47]

For the upstairs heating, can I put a plug in for the Salus programmable stats ? I have the <something>500 here (discontinued model) and it's great how you program a temperature profile rather than a single setpoint and on/off timer.
As for wiring all the bits together, sounds like an S-Plan candidate - zone valve for upstairs, another zone valve for the towel rail, another valve for the hot water cyl, and the UFH does it's own thing (just connect it's boiler demand relay in parallel with the zone valve contacts). The UFH, if it's using the right manifold setup, shouldn't need a zone valve - but if it does have a zone valve, just treat it as a standard zone valve for S-Plan purposes.
As already (sort of) said, there's a reg that requires a CPC to be run to every point in the system - so required at every stat even if the device currently fitted doesn't need one.

 

[Peter1891]

For the upstairs heating, can I put a plug in for the Salus programmable stats ? I have the <something>500 here (discontinued model) and it's great how you program a temperature profile rather than a single setpoint and on/off timer.
As for wiring all the bits together, sounds like an S-Plan candidate - zone valve for upstairs, another zone valve for the towel rail, another valve for the hot water cyl, and the UFH does it's own thing (just connect it's boiler demand relay in parallel with the zone valve contacts). The UFH, if it's using the right manifold setup, shouldn't need a zone valve - but if it does have a zone valve, just treat it as a standard zone valve for S-Plan purposes.
As already (sort of) said, there's a reg that requires a CPC to be run to every point in the system - so required at every stat even if the device currently fitted doesn't need one.

Hi, yes I know people have made a point about the cpc I will of course run one in all areas it’s required so anything 230v that’s not my worry I’ll be ok with that side of things once I get to it but I’ve only been out on my own for 4/5 years and I’ve not done anything this complex before I know it’s likely second nature to you guys but everyone has to learn sometime. I’m just lost trying to figure out how best to connect it all up as everyThing is in separate locations, boiler in garage, hot water tank in airing cupboard along with valves for towel rad and hot water and upstairs rads I assume while the ufh manifold is downstairs in a cupboard.
Am I best of leaving the ufh manifolD wiring centre with it and doing a separate wiring centre for water and rads?

 

[ETradesmen]

Hi, yes I know people have made a point about the cpc I will of course run one in all areas it’s required so anything 230v that’s not my worry I’ll be ok with that side of things once I get to it but I’ve only been out on my own for 4/5 years and I’ve not done anything this complex before I know it’s likely second nature to you guys but everyone has to learn sometime. I’m just lost trying to figure out how best to connect it all up as everyThing is in separate locations, boiler in garage, hot water tank in airing cupboard along with valves for towel rad and hot water and upstairs rads I assume while the ufh manifold is downstairs in a cupboard.
Am I best of leaving the ufh manifolD wiring centre with it and doing a separate wiring centre for water and rads?

Treat them as different wiring centres that are in a way connected together.
If you wire all the other components to the manifold you're going to have to extend all the zone valve cables and have a beast of a wiring center to tackle. You’re better off spreading the amount of cables around to even the amount of cables. You only need a 3 core and earth between the manifold to main wiring center.

 

[Peter1891]

Treat them as different wiring centres that are in a way connected together.
If you wire all the other components to the manifold you're going to have to extend all the zone valve cables and have a beast of a wiring center to tackle. You’re better off spreading the amount of cables around to even the amount of cables. You only need a 3 core and earth between the manifold to main wiring center.

Thank you for your reply. That’s what I was assuming.
So if I install the ufh wiring centre at the manifolds location in the downstairs cupboard then install another linked wiring centre in the airing cupboard is that what you mean? Thank you for your replies.

 

[Timbo]

Towel rail circuits are not normally zoned, the flow is tee'd off just after the pump/before the zone valves so that whichever zone is heating up the towel rails are on. It's cheaper, too. Saves on zone valve, timer, wiring and install time.

 

[ETradesmen]

Thank you for your reply. That’s what I was assuming.
So if I install the ufh wiring centre at the manifolds location in the downstairs cupboard then install another linked wiring centre in the airing cupboard is that what you mean? Thank you for your replies.

Yes, that’ll work.

 

[Simon47]

Thinking a little more about this - I bet they're just throwing an unvented cylinder in, while this is a situation just crying out for a thermal store (with passive heat exchanger coil for DHW).
Thermal store - separate tappings for UFH & rad loops, pump on manifild does UFH, separate pump does rads, not a zone valve in sight. If you say those two words within earshot of ths plumber, I bet you'll get a sucking of teeth followed by a gazzillion old wive's tales to show hiw truly awful they are.

But back to your job ...
Yes, UFH wieing centre next to the manifold - otherwise that's a sh*tload of extra wiring. Regular S-Plan wiring centre where all the zone valves etc are. Link them with at least 4 (four) cores plus CPC. You'll need L&N from main wiring centre to UFH, and you want to allow for volt-free contacts going the other way (so 2 more cores). You might not need volt-free now - but a future boiler change may alter that (some have a low voltage control input).
If the boiler isn't licated with the main WC, then alliw 4 cores again - to allow for volt-free control if needed at a later date.
And not forgetting 3C+E for a wall stat/controller for the rads - my mantra is to have wired if possible, wireless is for when it's not practical to wire.

 

[Peter1891]

Thinking a little more about this - I bet they're just throwing an unvented cylinder in, while this is a situation just crying out for a thermal store (with passive heat exchanger coil for DHW).
Thermal store - separate tappings for UFH & rad loops, pump on manifild does UFH, separate pump does rads, not a zone valve in sight. If you say those two words within earshot of ths plumber, I bet you'll get a sucking of teeth followed by a gazzillion old wive's tales to show hiw truly awful they are.

But back to your job ...
Yes, UFH wieing centre next to the manifold - otherwise that's a sh*tload of extra wiring. Regular S-Plan wiring centre where all the zone valves etc are. Link them with at least 4 (four) cores plus CPC. You'll need L&N from main wiring centre to UFH, and you want to allow for volt-free contacts going the other way (so 2 more cores). You might not need volt-free now - but a future boiler change may alter that (some have a low voltage control input).
If the boiler isn't licated with the main WC, then alliw 4 cores again - to allow for volt-free control if needed at a later date.
And not forgetting 3C+E for a wall stat/controller for the rads - my mantra is to have wired if possible, wireless is for when it's not practical to wire.

Hi mate,
Thanks for this,
I figured out the wiring centre for manifold which I’ll install next to manifold as like you say they’ll be stupid amount of cable otherwise extending them.,
I’ve realised I’ll need two wiring centres one for ufh and one for upstairs rads and water etc all the two ports.
my only issue i have now is how do I link them both either together or to the boiler? Surely the boiler only has one switched feed so if I connect both wiring centres to it surely both systems will come on together?
I need them all to work independent of each other upstairs rads and downstairs UFH manifold.

 

[davesparks]

I’d personally wire all the U/H programmers back to the manifold and then take a 3 core and earth (run two just to be safe)

Don't waste time and materials running extra 'just to be safes' work out what cables are required for the correct connection of the system and run those cables.
[automerge]1592950473[/automerge]

I’ve only been out on my own for 4/5 years and I’ve not done anything this complex before I know it’s likely second nature to you guys but everyone has to learn sometime.

Did you not learn how switches and relays work and control loads during your apprenticeship?

A domestic boiler control circuit is just a bunch of switches connected so that they switch a couple of different loads as required.
Programmers and thermostats are,as far as the control circuit is concerned, just switches, a 2 port motorised valve is, as far as the control circuit is concerned, no different to a basic relay.

You need to learn how the circuit works rather than starting with worrying about the number of cables or just joining things up by colour or number.

 

[Simon47]

I’ve realised I’ll need two wiring centres one for ufh and one for upstairs rads and water etc all the two ports.
my only issue i have now is how do I link them both either together or to the boiler?

Are you familiar with the wiring for an S-Plan system ? If not, time to go and do some swotting up You'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.