WiFi Thermostat Install

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Nick Hodges

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I’m wanting to replace my original Honeywell thermostat for a WiFi one but I’m stuck on the wiring.

I have a grey, earth, black (with brown sheath) and brown wire.

Im told the new thermostat only requires a live and neutral, with a possibility of needing to bridge across 2 connectors.

The old one was wired using the brown and black wire.

any help much appreciated.
 
Photo would be better,but sounds like you have a live, neutral, earth and switching wire. Standard setup for that type of stat. Photo of installation picture of new stat would help or instructions link.
 
upload_2020-10-10_21-26-39.png


Thanks for your reply. This is the diagram I was told to follow and the old thermostat housing. With this configuration, the new thermostat just blinks on and off.
 
See, a picture tells a 1000 words. So you currently have a live and a switched output (Black with brown sleeve). You need to find out if your grey (not connected that I can see) is used as a neutral, if it is then brown to L, grey to N, link L to com (4 to 1) switch live (blue on your diagram - Black with brown sleeve) to 2. So your not far off, just need to confirm the neutral.
 
upload_2020-10-10_21-42-37.png


That is NOT a neutral connection.
The little rectangle represents an appliance (boiler?).

The grey wire MIGHT be a neutral. You will have to test or look at the other end of the cable.
 
As far as I am aware Nest e is the only wireless thermostat which does not require a neutral supply to the base.

And the NTC shown on new one tends to make me think it is for under floor heating where they have to ensure floor no hotter than 27°C although it may be a user option rather than requirement.
 
Okay, so I think it may have something to do with the fact that my old thermostat was battery powered. Would this mean there is no live?
 
Nick Hodges said:
Okay, so I think it may have something to do with the fact that my old thermostat was battery powered. Would this mean there is no live?
Click to expand...

No there’s live and switched, no neutral was required because it was battery powered. The grey wire could be neutral, you need to test it.

Afaik the only battery ones, that are solely battery operated thermostats are wireless ones, but even these need a powered receiver and switching wires. One exemption being the intergas eco rf 30 boiler which has the receiver/software built in to the boiler.
 
ericmark said:
As far as I am aware Nest e is the only wireless thermostat which does not require a neutral supply to the base.

And the NTC shown on new one tends to make me think it is for under floor heating where they have to ensure floor no hotter than 27°C although it may be a user option rather than requirement.
Click to expand...

The unit I have can come in different variations including underfloor heating, but I’ve been assured this one is for just heating.
 
A multimeter or 2 pole voltage tester. Test between your live at a (leave it connected to Honeywell for safety) and the grey, If you get 230/240vac then I’d say it’s ok, however test between grey and earth should be 0vac - 15vac. Or you could trace the wire if feasible.
 
I would say 217 volt too low to be a direct supply. AC has capacitive and inductive linking so a disconnected wire can show voltage with a high ohms per volt voltmeter, with the old AVO mark 8 I would measure using two ranges is voltage did not match then likely just due to linking not a positive connection.

Putting it simple guessing in no good.
 
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