Central Heating Electrical Wiring - Part 1

Part 1 in a series on wiring UK central heating systems. This is an overview of the various components.
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[@audiovideosouthwest]

A delight to see a clearly structured presentation without ghastly distracting music and wobbly pictures. Thank you so much John. I know how much work these are to do.

[@mmack3286]

Thanks John I'm apprentice plumber and I'm trying to get my head around the wiring and I'm learning from you instead of my lectures as they are crap. You make things and explain things in a good way.thank you

[@dannyetim8677]

Thank you john, I'm apprentice plumber I've been onsite with engineer for newly 1 year but I learn more from you. This is really helpful. God Bless you.

[@ohforfxcksake]

I work on combis mostly but always come back to these videos when i know I've got an s plan or y plan problem coming up. Thanks for making it so simple

[@jillroberts9819]

Thankyou for taking the time to make this video. The advice about the fan continuing to run to help disperse heat answered our wiring dilemma and saved the time & expense of calling out an engineer. 🙂

[@TheDickPuller]

Well done JW a first class explanation of the CH control system. I'm sure even the hard of thinking will follow that.

[@TheMaintopman]

Spinmaster I wish I had seen your videos years ago. Very clearly presented and easy for a layman to understand. Thanks

[@johnmac8084]

Thanks John, I've been watching your videos this weekend and they are very well presented & helpful. Sorry to be pedantic, but at 19:43 I have found, in my experience as a heating engineer, that the most common arrangement is Off, Off, On, On, rather than the other way round i.e. HW Off, CH Off, HW On, CH On

[@Adzz7x]

Thanks for your continued high quality videos John, you explain things properly and in a clear way. Keep up the good work!

[@neilcaldwell870]

I always wondered why the older thermostats had a Neutral connection. As always John a brilliant explanation. Thanks for your clear explanations.

[@ockeridge]

Thanks JW, brilliant video!! Just the right pace from beginners to advanced! I for one found it very useful! Keep the videos coming!?

[@whopaimon5407]

Great Wiring video, very useful and informative for both Central heating engineers and home owners. I have learnt a lot. Thanks John Ward Sir !

[@DH-vw2xy]

Fantastic videos. You go through things in such a methodical and easy to follow way. Thank you

[@tokerstar1]

Top work John! Please release the next part asap, thanks.

[@tony7077]

God bless John, most helpful video on KZbin!

[@brianburke396]

One of the best, if not the best video explations on electrical layouts and regsI've seen, well presented and good clear accurate information, a pleasure to watch,,,,,, keep up the good work, well done, could you do some tutorials on relays, contractors, recycles etc,,, just a suggestion.

[@johnm8016]

Thanks for the very interesting videos. Just for interest:- My system has a gas boiler, a pump and a programmer but only one valve to shut off the heating if not required, giving priority to water by gravity. Hope that makes sense to you. The valve opens when heating switches on. The whole system was installed by a friend in 23 hours(working) and we have a 4 bedroom house, he done it this way to keep the price down, I bought all the parts and he installed it, he charged us £80 labour so you can guess how many years ago that was. I've only had to replace the programmer, a Randall 3060 I think it was, with a Honeywell programmer which we still have and the boiler, everything else is still going. I've also still got a few lengths of 3/4" piping, it's amazing how thick the wall of the pipe is compared to todays standards. Thanks again and I've subscribed so will be popping back now and then.

[@gp2580]

Brilliant informative and clear video once again John. Very grateful to you.

[@boxsecurityltd6944]

Excellent work John, you have saved us a great deal of embarrassment, bit lost before watching this video good work, thank you.

[@dannymort7262]

thanks for the video John. I appreciate the effort you must go to in order to provide these videos, they're really helpful and appreciated

[@timoriordan1]

I Totally agree with your comments

[@Stevewadey]

Excellent video. Thanks for posting. Really easy to follow.

[@nickhughes9144]

Great tutorial, very clear and concise, thank you.

[@jameshansing5396]

Another great video from the legend himself...

[@6november75]

Very very good video well explained and easy to understand thanx

[@gonzalomartinez1630]

Thanks John, this is a great help.

[@abdulhafiz6923]

Great video. Very easy to understand

[@TheManWithTheHat]

Hello John. Thank you for a very interesting video.I’m especially interested in the part with the wireless thermostat and receiver box on the wall near the boiler.I have just bought the nest system and I’m sure I can fit it all myself except I am confused with one particular wire. How do I know which wire is the “call for heat wire” and how do I locate it?

[@stephendavis891]

Jw strikes again top video 👨‍🏫

[@sunindragupta9236]

amazing video, well explained

[@francisexperience]

Always great presentations thank you

[@jimm533]

Brilliant, answered alot of questions

[@rileyfreeman3670]

John Ward, you are my hero

[@davidphilipleeful]

You are a legend John thank you

[@gkoster99]

Excellent videos and information - thank you. I now know what all those wires and boxes do! A question - I'm considering installing a Nest Thermostat (third generation) and wondered if you could post a wiring diagram for the Nest system. Would also be useful to then see which components (and wiring) of the existing system effectively become redundant as a result (Eg the programmer and the wiring to/from?)

[@cathyscullion1691]

Hi John can you run a video on electrical connection and equipment required for domestic/commercial solar ( photovoltaic system) and explain how dc and ac converts in this system. Thanks

[@alex_spheres5578]

Did you know a person i know goes to sleep with this on in fact he has subscribed to you!

[@Goboholder]

Any particular reason why the resistor in the controller is on the neutral, and not on the switched-live??? Thanks for a great lesson.

[@chapp2012]

I have a very old "boulter camray 5 oil fired boiler" and recently when I had to replace the programmer I found it only has a pump on the central heating side and nothing on the hot water side. When the hot water comes on it just turns on the boiler. When the heating comes on, only the pump turns on, meaning that you have to have the hot water on at the same time to heat the water.

[@mike004692]

hi John , what cable should I be using wiring this system up , I am used to using 2 core twin and earth , but when I look at 3core and earth they are all new colours , not brown , blue and earth ???

[@FMDoop]

Wow John - Well done. Nice

[@green2489]

Hi JW, I love your videos. They are a great learning tool for me, but correct me if I'm wrong but doesn't your explanation of the programmer output terminals for 'HW ON' and 'CH ON' in this video contradict the explanation of the tutorial in your S Plan video? (Part 2)

[@Sparks9133]

Great video 😊

[@smellylampshade]

Very useful, thank you

[@jamessinnott3399]

hi john great video im just wondering if you could do a video on non-proirty unit for a 2 shower system if you have ever seen one?

[@JohnSmith-ju4vw]

Most boilers these days actually have (besides the permanent supply) an LS, NS and LR connection. LS and NS supply the control system while LR is the switched live which fires up the boiler.

[@samarchaudhary2899]

Thank you JW

[@alexanderfrench9236]

Great video

[@ez8294]

What is the correct order all the testing procedures for a newly installed central heating boiler circuit ?

[@laernulienlaernulienlaernu8953]

I would estimate that about between 2/3rd and 3/4 of fully pumped systems are Y-plan (1x 3 port valve) and the majority of the rest are S-plan (2x 2 port valves) there are some obscure ones like C-plan with 1x 2 port but the majority are quite simple. It’s surprising how many electricians don’t know how to wire heating systems even though it’s just motors and switches in principal

[@tombelmonte2502]

Awesome video Thanks

[@michaelholohan9224]

Best thing on KZbin

[@nateryan7041]

Great video 👌👌👌👌

[@studiosys]

Love it ! Nice presentation , I. Can almost hear your brain ticking over ( logical steps )😊

[@dasy2k1]

The majority of wireless thermostats these days have the receiver integral with the programmer which makes it slightly easier to connect

[@steveforks9698]

Thanks great in4

[@user-yh4kl3hx2o]

Your and absolutel legend

[@alfazulo2330]

Sorry, you have two pumps in that sistem right?

[@nisarhanif8805]

Hi John. Very informative thank you for the explanation. Just wondering when are the next parts to the video coming out? Thank you.

[@jwflame]

+nisar hanif Should be this week.

[@user-kj4js4pt5z]

thanks jhon just the ticket 👍

[@chompchompnomnom4256]

Hi John, is it really true that if you turn off unused radiators its saves gas? Because our thermostat is in one room so therefore how can turning other radiators make a difference?

[@jwflame]

+ChompChompNomNom The only way turning off unused radiators saves any real money is if the unheated rooms are well insulated from the rest of the house, and the doors to those rooms are permanently closed. As this is never the case, not heating one or more rooms just means the heat losses from the other rooms are much greater, as the heat moves from the heated rooms to the unheated ones through the uninsulated walls / floor / ceiling.

[@laernulienlaernulienlaernu8953]

There are still new boilers that only require a switched live, they only require a permanent live if they require a pump over run to circulate residual heat from the heat exchanger and all new pumps now must be “smart” pumps that modulate their output depending on the load on the system

[@laernulienlaernulienlaernu8953]

pmailkeey, Ideal icos needs a permanent live so you can tell when the £200 circuit board has packed in again!

[@brendannicholson3947]

Is it possible to simply use a smart mini wi-fi switch to connect across a central heating programmer to switch heating on/off remotely using an app?

[@jwflame]

Yes, programmers are just switches, so pretty much any switch can be used, smart or not.

[@user-rn5ip9ec6j]

Thanks! 👍

[@Yes-ng6rf]

Strange that you use low voltage (240Vac), control there still, we have been using PELV here for as long as i can remember, a suitably sized 24volt transformer in the boiler powers everything else (except the pumps), those are controlled by 24vac relays. There should be an over temperature cutout (manually reset safety), in the boiler too. Great video just the same, you might catch up with us convicts one day :)

[@damienstewart4736]

We do have 24 volt stats .on some boilers you have terminals for both

[@mariarossi6719]

I have a question which I can't find the answer to on Google and am hoping you might be able to help. When I was cleaning the other day, I accidentally went a bit too close to the central heating control panel and I think the smallest amount of water from the sponge must've leaked its way down inside. The control panel started to flicker and slightly buzz. I grabbed a wooden spoon and switched it off as quickly as I could. I haven't put it back on yet. Wondering if it would be safe to switch back on or even put the heating on or should I leave for perhaps longer? Have tried searching on Google but cannot seem to find an answer anywhere. Would really appreciate any advice. Thanks so much.

[@jwflame]

If it has dried out it may still work, but if enough water got in to cause it to malfunction, there is a very good chance it has been damaged permanently.

[@animarkzero]

Nice heating explantion! I do not get it why the valves are built this way in GB? Wouldn't it seem rather inefficient to have the valve always powered while open(which is most of the time)? Why even have a valve at all?? In most cases just a pump would just suffice! In Austria where I live mixing valves are used sometimes which use an actuator(motor). Also gas and oil are so last Century! Heat pumps are the way to go!

[@timbradshaw3201]

Generally easy to follow - I always understood the brown wire to be Live not Line. Are they used interchangeably?

[@jwflame]

Terms have changed over the years. kzbin.info/www/bejne/i3bXhqqBmLeMqdU

[@adamfarmiloe]

Hi jw just a quick question I have a combi boiler with the standard programmer and I'm thinking of installing the hive thermostat dual chanel the question is will the hive replace the programmer or run alongside it like my existing thermostat does and maybe you could make a Video regarding these thanks Adam

[@jwflame]

Hive replaces both the programmer and thermostat, the one device does everything. A combi boiler is one which heats water on demand, there is no hot water cylinder, those need a single channel hive. If you have a hot water cylinder, a dual channel hive is required.

[@adamfarmiloe]

John Ward cheers john it's just a boiler and there's a tank upstairs ..as for the existing thermostat would it be removed and the live and call be joined and a blanking plate be put over it or would that be done at the boiler and then the wires at the thermostat be made redundant. Thanks for the reply

[@jwflame]

That's it - you will need to dual channel one. The Hive has a standard backplate, so may just fit onto the existing programmer plate without any wiring changes. Thermostat wires either connected together at the thermostat position, or put a link in the wiring box and remove the thermostat wires completely. If you do need to remove any wires, mark them all first and take several photos of all of the wiring so you know where they were connected - colour codes and terminal numbers can be different depending on who installed it originally.

[@adamfarmiloe]

John Ward cheers jw

[@elisab7652]

Hi - we have switched the electricity off in our house as we are going away. The boiler will obviously also be switched off. Is it a problem/is it dangerous?

[@jwflame]

Not dangerous. The pump might seize if it's left for a very long time, and if it's in the winter freezing could cause damage.

[@oOoR1CH1EoOo]

If a boiler is 6kW ( 2x 3kW) elements how does this work because surely that draws 26A and not 3A ?

[@jwflame]

It would, but the connection for an electric boiler would be a separate circuit just for the boiler. These videos are about the control wiring, not the means of heating, which is usually gas or oil.

[@lesj15]

Hi John. when I turn on my boiler it trips the rcd any advice would be welcome.

[@jwflame]

+Les James Most likely water leaking somewhere inside the boiler onto the PCB or other electrical parts.

[@lesj15]

+John Ward Thank you for the prompt reply.

[@user-ef9rk8ln1f]

John.. please.. on my heating/water control panel, Drayton lp522 .. is the yellow light meant to stay on all the time.. Is it wired properly and can I turn it off from inside the panel..

[@jwflame]

The yellow light for the central display stays on all the time. The small red indicators either side should go on/off to show whether the heating and hot water is on/off.

[@user-ef9rk8ln1f]

John Ward Thank you John.. I have seen the same one with no light on it though..??

[@jwflame]

@@user-ef9rk8ln1f There are several different models, all look similar, some have the backlight, others do not.

[@user-ef9rk8ln1f]

John Ward Oh dear.. Thank you Mr Ward..

[@DerekHundik]

how to connect this one to water tank Codice - Dual Combined High Limit Thermostat & Control 542791

[@jwflame]

Normally both thermostat contacts are wired in series, then the whole thing is considered as one thermostat, with two wires.

[@geoffhaylock6848]

".....electric though no-one would want one of those" Heat pumps enter the chat. 😁

[@MikeGleesonazelectrics]

Excellent tutorial.. On an S plan, when another heating zone is required with a second motor valve and second room stat, I'm guessing you use a spare terminal in the wiring centre and take the s/l from the second stat to energise the second valve input (orange) with the output going to terminal 10 as usual to fire the boiler?

[@jwflame]

Yes, it's the same for each zone. All of the outputs connect together. You can add as many zones as you want, each just needs a thermostat and valve.

[@Kaizer10155]

So can either gas or an oil boiler be a S plan?

[@jwflame]

Yes, makes no difference, it's just something that heats the water.

[@miketang448]

Nice work. We produce heating tubes in China. We have a big manufacturer.

[@Call4Justice]

This diagram seems to be totally wrong as on Drayton Lp112 programmer, terminal 1 is HW off, 2 is CH off, 3 is HW on and 4 is CH on. Any comments?

[@jwflame]

Some programmers have different terminal arrangements. So do some thermostats. And so do other things like Hive, Nest and the rest.

[@steverodgers1112]

Using mains voltages at the thermostats seems unusual. There must be a historical reason for this. Here in North America, the majority of heating, ventilation, and cooling systems (HVAC) use a low voltage such as 24 volts AC to power AC switches back in the central heating unit.

[@Graham_Langley]

+Steve Rodgers Used not to be the case. My parents first CH boiler (gas) installed in '68 used 24Vac for the roomstat. I can't remember what the cylinder 'stat used.

[@jamesgrimwood1285]

in the UK we don't have "HVAC", we have "central heating" that is solely concerned with warming the place up. Really old systems have no electronics to control any of this, I've lived in a house where the boiler timer was a mains powered mechanical clock timer and the thermostat a simple bimetallic strip. So switching mains voltage makes sense.

[@Graham_Langley]

Hi John. I'm afraid you've got the connections to the cylinder coil the wrong way round. Edit: Now I've watched the whole video, there may not be an earth connection to a valve motor head if it's isolated from the valve body. I've got a pair of Sunvic valves here with plastic-bodied motor heads and just Live, Open, SwL plus Neutral - no earth.

[@jwflame]

+Graham Langley Easier to draw that way, avoids the flow/return crossing over. Sunvic valves are generally evil, they also make those which have motor on / motor off an no spring. A good idea but poorly implemented, they don't last long before some failure occurs.

[@Graham_Langley]

+John Ward Their MoMo ones are exactly the ones I have, chosen because I wanted to be able to mimic way the old Switchmaster 3-port valve worked. The mechanics seem OK, the cct is OK with the 24V zener across the relay and the current-limiting resistor put back in, but the PCB design is terrible with too small clearances for mains voltages. I'm tempted to layout a new one instead of just replacing the worst track with a wire link. Edit: But it's no where near as bad as their Select 207xl programmer. I fixed a neighbour's one that failed on New Years Eve a few years back. How they could sell such a badly designed and produced bit of kit is beyond me. Swapped it for a Siemens RBW9 a few days later, discovering in the process that 'universal' backplates aren't.

[@Graham_Langley]

+Graham Langley Perhaps I should add that the Sunvic MoMo valves won't emulate the Switchmaster, which stays in the last position and only moves when the demand changes, on their own. They need a home-brew controller, which can also give hot water priority.

[@zebakhtar4022]

Graham Langley i was looking at the same thing there. flow and return wrong

[@alirezajouzdany971]

IT IS VERY USEFULL FOR ELECTRICIAN BUT,YOU ARE TALK VERY FAST.PLEASE TRY TO TALK SLOWLY

[@reddragon27284]

I don't know anyone who still has a water tank these days. Everyone I know, myself included, has a combi boiler that heats water on demand.

[@jwflame]

+RedDragonUKTech Combi boilers are single outlet devices. Useless in a property with 2 or more bathrooms. They are frequently installed because they are cheaper and quicker to fit than a proper hot water system, rather than because they are actually suitable. There is also a myth about them being more efficient as they only heat what you use, but this is nonsense as most of the heat losses are from the pipework between the boiler/hot cylinder and the outlets.

[@reddragon27284]

+John Ward fair one, that makes sense. It's still something I don't see very often.

[@cyberdragon3699]

+John Ward We have a half sized electric heater tank that feeds two bathrooms from one standard sized pipe. The pressure drops when you turn both sinks on hot. We had a problem with rusty water coming from the kitchen sink once. The plumber found the cause to be a bad anode in another miniature heater tank that was inside the wall under the countertop near the sink. @_@ That plumber will have nightmares.

[@laernulienlaernulienlaernu8953]

Some digital thermostats only require the two switch wires and they use batteries to power the electronics

[@busman2000]

In today's Green and Eco conscious environment are people becoming reluctant to have oil and gas boilers for heating and switching to Air Conditioning systems instead, or would that be price prohibited with the cost of electricity..?

[@jwflame]

Gas is far cheaper than electricity (4x), so for most installations gas is the usual choice.

[@kallumarrowsmith2046]

What is your job John? Because you seem to know a lot about everything.

[@bassboostedbacon9262]

lol

[@bassboostedbacon9262]

first

[@alanroche2845]

Pump go's on the return not the flow.

[@alevsamra]

WHY are you talking so fast ?? Its crazzy, i dont get anything !

[@simon_bingham]

Good video , so testing a boiler it should be ok to apply live to live and SL at the same to to make it work.