Honeywell T40 to moes bht-002 installation help

A red (Brown in current regs) sleeved wire would indicate a live in my opinion. Colours mean nothing in a heating system. Any photos?
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Thanks for your reply.
The blue cable on the connector block as got a red sleeve (same as the yellow cable).
My question is how the T40 thermostat is working:
The link is between the the live and the switch live and every time the wheel is turned it opens and close the contact. So I’m this instance what the blue cable is doing? Will the T40 work without the blue cable? If it still work can I use the blue cable as neutral?
Looking at that you appear to have an s plan system (x2 2-port valves) do you have a hot water cylinder? Please post a photo of thermostat end as well, that’s the junction box/wiring centre.
Yes, I have a hot water cylinder as well.


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Ok, not sure that’s a T40, but looks like a T6360 (might have had number changes). If wired correctly 1 is live in, 2 is neutral and yellow (sleeved red) is switched live. On your Moes Go (if that’s what it is) will need to be wired up where the wires are in 1st photo provided. You need to trace which wire is live (assuming red if correct) to go to Live on Live on WiFi stat, pick up a neutral or use the assumed neutral, take a link between the live on wifi and normally closed, use switched live on normally open.
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I have tried but it is not working, when I test voltage between live and neutral (at the thermostat) I have only 20v, this is why I believe I don’t have neutral.

Do you know what is the purpose of the neutral cable at the Honeywell thermostat?
Will the thermostat work with just live and Switchlive?
The neutral is there to heat up an anticipator, to stop wide temperature swings. It will work without a neutral, but bigger temp swings. It could be wired up wrong, as in back to front.
I understand.
What will happen if at the junction box I disconnect the blue cable from the connector block and wire it with the neutral block and at the new thermostat I have the live, the neutral and Switchlive (and the link)?
Sounds feasible enough, and should work.
Ok, not sure that’s a T40, but looks like a T6360

I always call this thermostat a T6360, but sometimes it does get referred to as a T40. The diagram inside the lid might give a clue as to why both terms are used.

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I always call this thermostat a T6360, but sometimes it does get referred to as a T40. The diagram inside the lid might give a clue as to why both terms are used.

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Cheers @stem, can’t say I’ve ever noticed, I just fit them as a retrofit, and know where the wires go and how to test between the terminals.
I am back
Unfortunately my experiment didn’t work.
I have buzzed the cables from the junction box with the one in the thermostat and none of them worked so I couldn’t bring the neutral to the thermostat.
Now I’m stuck, I have found a power socket close to the stat, I was wondering if I can run a live and neutral from the socket to power up the thermostat and use the exiting live and the switch live for the opening and closing of the heating and don’t use the blue cable.
Is it risky to do it?
It’s very risky yes, and personally wouldn’t recommend it. Did you check all wires were touching the connection as opposed to being crimped on insulation?
I checked every wire and honestly it seems very weird as I have only one 4 cores cable going up in the ceiling. I will try tonight to buzz them with a long lead but I am pretty sure that is not my cable. I don’t want to start to lift floor boards up to see where the cables are going but I will keep it as the last option.

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