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shindigger

Thermostat Wiring Tips.

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Hi

Im changing my dads wall thermostat to a model with an indicator light on it. Its this Honeywell model.

http://products.ecc.emea.honeywell.com/europe/pdf/en0r8281uk07r1204.pdf

I've wired it up, and it works, but the light is not coming on when a call for heat is sent.

I intentionally bought the same model to avoid wiring grief.

That link points to a set of wiring diagrams on the last page of the document.

With particular regard to top row, middle diagram, what does the dotted line indicate?

Is it saying that this wire is internal and hidden or is it telling me i have to spur a short jumper wire between terminals 2 and 3? Or spilt the neutral feed to 2 ad 3?

My current wiring is exactly like the diagram to the immediate left. (The first, most basic, one.)

I have 2 wires, a neutral and a live. The earth is bent behind the unit and is not used.

I think this diagram is telling me that the lamp is factory wired to internally spur off of the neutral connection, and if that's the case ive bought a unit with a dodgy lamp. It does in fact say that the lamp is internally wired on tip sheet.

Cheers for any help.

And i wont hold anyone responsible if i wreck something!

Tried speaking to Honeywell but they wont speak to householders.

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From your instructions:

Indicator Lamp

A 'potential-free' indicator lamp is available on some models.

This can be wired as required to indicate when power has been switched to the (heating or cooling) load (see Wiring).

To wire the lamp as 'boiler lockout' indicator, follow boiler manufacturers wiring instructions.

This means its optional and you need to run a jumper wire if you want the lamp function.

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I've wired it up, and it works, but the light is not coming on when a call for heat is sent.

I may be misunderstanding what you have written (I'm no expert on thermostats), but...

I helped my Dad fit one of these (it looks like the same model) - as far as I remember, the indicator light is on when the heating system has power - not when the thermostat sends a heating request to the boiler.

So the light would be on solidly from 6am to 10pm if your heating system is 'available' between those times - like in the winter. At the moment his thermostat has no light as it is summer and the heating system is effectively off.

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Spec sheet is for multiple models, some with and without indicator light. The dotted line indicates that it will not always be present on some models. Should be prewired and ready to go.

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Its contradictory.

On one sheet (the one that came with the unit) it says its internally wired. I take that as meaning ready to go, and the dotted line indicates this.

And on the generic web sheet (that i linked to), it says it can be custom wired. And the dotted line could also indicate that as well. :huh:

Both are likely. I'm no clearer.

I'm reluctant to change the wiring (jumper wire) as i've read stories of exploding time switches etc while these "experiments" were performed.

I think my unit is a dud.

Thanks much for all replies.

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I've wired it up, and it works, but the light is not coming on when a call for heat is sent.

I intentionally bought the same model to avoid wiring grief.

That link points to a set of wiring diagrams on the last page of the document.

With particular regard to top row, middle diagram, what does the dotted line indicate?

Is it saying that this wire is internal and hidden or is it telling me i have to spur a short jumper wire between terminals 2 and 3? Or spilt the neutral feed to 2 ad 3?

My current wiring is exactly like the diagram to the immediate left. (The first, most basic, one.)

I have 2 wires, a neutral and a live. The earth is bent behind the unit and is not used.

I think this diagram is telling me that the lamp is factory wired to internally spur off of the neutral connection, and if that's the case ive bought a unit with a dodgy lamp. It does in fact say that the lamp is internally wired on tip sheet.

Can see why there would need to be internal wiring changes for the lamp with heat/cool functions but would have thought the indicator lamp would be pre-connected - can you see a connection on the other side of the terminal at all. So you need to split the neutral feed so that it feeds 2 as well to power the lamp (and not take off three as that is the wrong side of the load).

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Can see why there would need to be internal wiring changes for the lamp with heat/cool functions but would have thought the indicator lamp would be pre-connected - can you see a connection on the other side of the terminal at all. So you need to split the neutral feed so that it feeds 2 as well to power the lamp (and not take off three as that is the wrong side of the load).

Thanks.

I might take it to bits and look for a hidden contact between 2 and 3.

I've emailed Honeywell in the meantime.

When you say "split" do you mean a physical "Y" spit prior to hitting the terminals, or will just jumping from 2 to 3 do the same?

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All you are try to achieve is an indicator light in parallel with your heating load. That's a light that comes on when the heating load is energised. The thermostat switch energises both at the same time.

do not couple 2 and 3 (and neutral) as that would be a dead short.

you need a wire from the neutral to terminal 2 and that's it done...... BUT do you have 3, (or 4 cores) or just 2 (ignoring the earth)?

if there are only two wires then its not actually 'Live and Neutral', but just a switch in the live line, the neutral for the heating load must terminated elsewhere and would require another cable to bring in a neutral.

I wouldn't bother if that's the case, just live without the indicator light, or call in a '17th edition' qualified electrician, he'll sort it for you.

[anything I've written above should not be interpreted as a substitute for on site professional advice. DIY electrics can result injury, death and destruction of your property, and may be illegal or invalidate your domestic insurance ]

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All you are try to achieve is an indicator light in parallel with your heating load. That's a light that comes on when the heating load is energised. The thermostat switch energises both at the same time.

do not couple 2 and 3 (and neutral) as that would be a dead short.

you need a wire from the neutral to terminal 2 and that's it done...... BUT do you have 3, (or 4 cores) or just 2 (ignoring the earth)?

if there are only two wires then its not actually 'Live and Neutral', but just a switch in the live line, the neutral for the heating load must terminated elsewhere and would require another cable to bring in a neutral.

I wouldn't bother if that's the case, just live without the indicator light, or call in a '17th edition' qualified electrician, he'll sort it for you.

[anything I've written above should not be interpreted as a substitute for on site professional advice. DIY electrics can result injury, death and destruction of your property, and may be illegal or invalidate your domestic insurance ]

Thanks Giraffe.

Yes i just wanted a light on the fascia to be a visual reminder for my dad.

I have 2 wires, plus (i assume) a bent back earth.

So i conclude, i'm screwed.

I'm sure if i dig back in the plaster i'll find a 4th cable, but i'm not going there.

Just to clarify re the dashed/dotted lines on the diagram.

Honeywell refer to this lamp as being "internally wired". Does that mean that 2 and 3 are linked and its already discretely connected, or, that it could be internally wired?

In which case all the connections could be referred to as being "internally wired".

Its a poor description if you ask me.

I'm just trying to establish whether i've bought a faulty unit or not.

Thanks again.

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From your instructions:

This means its optional and you need to run a jumper wire if you want the lamp function.

That sounds about right! I have a similar thermostat, and the light works on mine! I just checked it! I didn;t install it! It as been here since I moved in! ;)

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Yes the dotted lines are to show an option that's not primary to the function (switching). I agree the point would still have been understood (perhaps more clearly) if the existing internal wiring to the lamp had been drawn in solid lines.

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That sounds about right! I have a similar thermostat, and the light works on mine! I just checked it! I didn;t install it! It as been here since I moved in! ;)

I shouldnt ask....,BUT!!

Would love to know if you've got a seperate wire running to terminal 2.

Please feel free to tell me to do one. :D

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  • 242 Brexit, House prices and Summer 2020

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