Is my boiler wired right?

rewireIT · Jun 15, 2023

Just looking at my boiler wiring out of interest, and just wondering if it's wired correctly.

So perma lives, neutrals and earths in the right place, but i can't figure out the switch lives to the controller.

If i follow the circuit it seems like the earth of the 4 core is acting as some sort of live to the controller even though the perma live is already there. If i volt stick it, the earth is live at both ends at all times, the black is showing 50v amperage only sometimes and then dead others.

From the wiring diagram i would have assumed the 4 core would go to the switch as L N E and the black would act as the sole switch wire.

What am i missing?

(Ps thanks for your help - i'm trying to get more into the domestic side of stuff having grown sick of site work so this is my first foray into stuff like boilers.)

PPS the controller is not a stat, it's just on/off. Timer/temp etc is built onto the boiler.

brianmoooore · Jun 15, 2023

Just because a wire is green/yellow doesn't necessarily make it an earth, especially if plumbers are involved!
Your controller is wired as 'volt free' , and the green/yellow has been used as a 'live'.
There doesn't appear to be a real earth at the controller, but it does look like there's one at the boiler.

rewireIT · Jun 15, 2023

brianmoooore said:
Just because a wire is green/yellow doesn't necessarily make it an earth, especially if plumbers are involved!
Your controller is wired as 'volt free' , and the green/yellow has been used as a 'live'.
There doesn't appear to be a real earth at the controller, but it does look like there's one at the boiler.

The boiler is definitely earthed.

So could you talk me through the controller and what the '1' and '2' are doing on the boiler? I can't visualise how this works.

I gather the yellow/green is a live and the black is the switch, so what is the brown doing?

In my head, we have perma live in to boiler, out to controller. 240v out from boiler to the controller, button on controller than activates the black, turning the boiler on.

So howcomes the black is sometimes giving voltage sometimes not, when the controller switch isn't being operated?

brianmoooore · Jun 15, 2023

Your boiler wiring diagram shows a link between two terminals at the top. This link has been removed and connected to the green/yellow and black wires, which, at the controller end, are connected to the switch terminals. The blue and brown supply power to the clock of the controller.
A five core cable should have been used, of course.

rewireIT · Jun 15, 2023

brianmoooore said:
Your boiler wiring diagram shows a link between two terminals at the top. This link has been removed and connected to the green/yellow and black wires, which, at the controller end, are connected to the switch terminals. The blue and brown supply power to the clock of the controller.
A five core cable should have been used, of course.

Ah ok that makes sense - so the yellow is power in from the boiler, the switch is operated on the controller then the black switches the boiler on.

Still any idea why i'm getting a voltage reading now and again on the black without operating any switches? It seems to be intermittently going live but only registering 50v.

davesparks · Jun 15, 2023

rewireIT said:
Still any idea why i'm getting a voltage reading now and again on the black without operating any switches? It seems to be intermittently going live but only registering 50v.

What are you using to measure the voltage? Is it a meter with a high or low input impedance?

Most likely is capacitive coupling (aka ghost voltage)

rewireIT · Jun 15, 2023

davesparks said:
What are you using to measure the voltage? Is it a meter with a high or low input impedance?

Most likely is capacitive coupling (aka ghost voltage)

Fluke T90 which the spec sheet says 200kohms input impedance.

davesparks · Jun 15, 2023

rewireIT said:
Fluke T90 which the spec sheet says 200kohms input impedance.

Interesting, you wouldn't normally expect that tester to display a voltage of it was due to capacitive coupling.

Does that model have the button to lower the input impedance?

What are you measuring the 50V with reference to? Is that 50V to earth, to neutral or something else?

rewireIT · Jun 16, 2023

davesparks said:
Interesting, you wouldn't normally expect that tester to display a voltage of it was due to capacitive coupling.

Does that model have the button to lower the input impedance?

What are you measuring the 50V with reference to? Is that 50V to earth, to neutral or something else?

L to N is coming up 50v on the stick. It's the version that is just 'prod and play', without the button.

littlespark · Jun 16, 2023

Is there a fault with the heating, or are you just worried about the workmanship?

oscar21 · Jun 16, 2023

Wonder why they didnt take the timeclock live from the live output of the boiler, its a rare occurrence when the boiler switch terminals are actually marked in and out.

DefyG · Jun 16, 2023

rewireIT said:
just wondering if it's wired correctly.

Not if G/Y have been used for 'Live' conductors, therefore omitting earth connections and within cables.

Avo Mk8 · Jun 16, 2023

rewireIT said:
PPS the controller is not a stat, it's just on/off. Timer/temp etc is built onto the boiler.

That Honeywell R6660D is a wireless receiver, e.g. for a stat, intended to monitor room temp. Do you have the HCW80 or equivalent that goes with it?

I am puzzled by the 50V, but I'm afraid still a bit unsure exactly what you are measuring!
I guess the terminals in question (despite 2 being labelled 230V out) may be a control circuit, not necessarily directly connected to the 230V that's on the L terminal at the bottom.

If you are measuring terminal 2 wrt ground, I would expect 230V, given the label on the boiler, but if it's not that, it may be due to the source impedance of that voltage - though that seems unlikely given the 200k impedance of your probe.
Terminal 1 might assume any old voltage wrt ground with the R6660 off, as it's an input, and without the circuit diagram of the boiler, can't really determine.
If the boiler is working correctly, I think in the absence of a circuit diagram, you have to assume that terminals 1 and 2 are part of a separate control circuit not necessarily directly connected to the incoming mains, and be content that the voltages 'measured' don't indicate a problem!

DefyG said:
Not if G/Y have been used for 'Live' conductors, therefore omitting earth connections and within cables.

The Honeywell R6660 is ClassII device and has no provision for an earth, so you might argue there's no safety issue other that the failure to sleeve this one cable etc. etc.?

davesparks · Jun 16, 2023

rewireIT said:
L to N is coming up 50v on the stick. It's the version that is just 'prod and play', without the button.

Measure it to earth and also neutral to earth and post the results.

Does this all work correctly and as expected, or is something not working?

rewireIT · Jun 16, 2023

littlespark said:
Is there a fault with the heating, or are you just worried about the workmanship?

Nah was just having a look inside out of interest, boiler works perfectly - i just click the controller on and the boiler comes on, click it off for off.

Avo Mk8 said:
That Honeywell R6660D is a wireless receiver, e.g. for a stat, intended to monitor room temp. Do you have the HCW80 or equivalent that goes with it?

It's supposed to be wireless? No other equipment i'm afraid, just that and the boiler. I was gonna get a smarter thermostat but can't justify a couple of hundred quid to do what i can simply do manually.

Avo Mk8 said:
I am puzzled by the 50V, but I'm afraid still a bit unsure exactly what you are measuring!

When i just stick one pin of the voltmeter into the black i sometimes get 50v AC. On second thought it could just be the voltmeter showing that as part of showing an AC current since i wasn't measuring across more than one wire.

Avo Mk8 said:
If the boiler is working correctly, I think in the absence of a circuit diagram, you have to assume that terminals 1 and 2 are part of a separate control circuit not necessarily directly connected to the incoming mains, and be content that the voltages 'measured' don't indicate a problem!

I don't think there's a problem i'm just trying to work out in my head how the circuit works - who said house bashing was easy!

Avo Mk8 said:
The Honeywell R6660 is ClassII device and has no provision for an earth, so you might argue there's no safety issue other that the failure to sleeve this one cable etc. etc.?

Yep class II so no earth needed. Still poor imo to take the earth there as a live. Even some brown tape or anything woulda been better than just doing that.

Is my boiler wired right?

rewireIT

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