Changing old thermostat for smart stat

[Tracey0273]

Can someone tell me where the wires go from my old stat to the new please. Will I still need to bridge it? Thank you

 

[MJN]

Red (Live) -> 4
Blue (Neutral) -> 3
Yellow (Switched L) -> 2

No need for the bridge (assuming that's what you meant by the brown wire) as your new stat does it internally given the implication of the wiring schematic. Only were it to have a 'dry contact' (aka 'volt free') relay output like your old stat would it be needed.

 

[Tracey0273]

Thank you very much mjn. I'll give it a go

 

[SFK]

MJN suggestion is correct as per the diagram you provided (ie that the 240V is provided internally).

But the AC95's I have recently seen have needed the Jumper (as they have 'dry contact' switches meaning there is no internal 240V connected to the switch).
However, these being Chinese there might be many different versions of the AC95.

Tracy
Do you have an image of the back of the actual thermostat you plan to use?

Otherwise, start with MJN's suggestion.

If that does not work have a look at this page that shows the wiring to another AC95 that does have a dry contact switch.
https://www.diynot.com/diy/threads/...e-split-off-other-thread.560984/#post-4834154

SFK

 

[CBW]

I could be wrong, but the way I’m reading that diagram is the zone valve connects to the 2 bottom contacts and the neutral is taken from same source. In which case:

L to 4 (L on new stat)
N to 3 (N on new stat)
Yellow to Open (on New Stat)
Link the L on new stat to 1 on new stat.

 

[Tracey0273]

MJN suggestion is correct as per the diagram you provided (ie that the 240V is provided internally).

But the AC95's I have recently seen have needed the Jumper (as they have 'dry contact' switches meaning there is no internal 240V connected to the switch).
However, these being Chinese there might be many different versions of the AC95.

Tracy
Do you have an image of the back of the actual thermostat you plan to use?

Otherwise, start with MJN's suggestion.

If that does not work have a look at this page that shows the wiring to another AC95 that does have a dry contact switch.
https://www.diynot.com/diy/threads/...e-split-off-other-thread.560984/#post-4834154

SFK

Hi SFK. Here is a picture of the actual stat

 

[SFK]

Okay, so that is a Dry Contact switch.
(And shows once again the issue with Chinese goods not having proper wiring diagrams).

There is no 240V Live at 1 or 2 to fire your boiler.
1 and 2 is simply a switch with no volatages.

So you need to have the following (I swapped MJN's suggestion of pin 1 and pin2 around so that it matches the images used on the other OP page):

Red (Live) -> 4
Blue (Neutral) -> 3
Jumper Live (Short Brown cable) -> from 4 to 2
Yellow (Switched L) -> 1

When you Thermostat calls for heat, it closes the switch connecting the Live (from the jumper wire), to the yellow Cable, which fires your boiler.

Wireing should look same as this:
https://www.diynot.com/diy/threads/...e-split-off-other-thread.560984/#post-4834154

SFK

 

[MJN]

Hi SFK. Here is a picture of the actual stat
View attachment 220709

So not the diagram you posted then...

It's no bother though - follow SFK's instruction and you'll be fine.

 

[MJN]

However, these being Chinese there might be many different versions of the AC95.

I must admit, I didn't realise 'AC95' was a model number - I assumed the AC95-240V was indicating the acceptable voltage range! (95v to 240v)! Perhaps at one time it was but has evolved into something of a model name what does appear to be a highly copied device.

 

[Tracey0273]

The diagram was sent to me from manufacture and the stat arrived today. I asked for it in advance so I could get advice early. Thank you SFK I will do what you suggested

 

[CBW]

I must admit, I didn't realise 'AC95' was a model number - I assumed the AC95-240V was indicating the acceptable voltage range! (95v to 240v)! Perhaps at one time it was but has evolved into something of a model name what does appear to be a highly copied device.

I don’t think AC95 is the model number, and does indicate the voltage range. These are usually Moesgo thermostats, with different model numbers, usually G range such as GA, or BH002.

 

[SFK]

MJN and Chris,
You are 100% correct, the AC95 is not a model number, it is the first half of the voltage range.
But as there does not seem to be a model number for these products, so everyone uses it on ebay (and on this forum) for similar products as they all seem to use similar backplates and control circuits:
https://www.ebay.co.uk/sch/i.html?_...&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=AC95

Issue is that many have slightly different wiring settings. And some are for higher current switching (underfloor heating) and some for lower current applications.

And so my personal comment from the other forum stands:

Another Chinese thermostat - shudder.
And as before it is a pain to put on the wall as the black metal plate and white face plate never slots easily together.

 

[SFK]

The diagram was sent to me from manufacture and the stat arrived today. I asked for it in advance so I could get advice early. Thank you SFK I will do what you suggested

Pleasure and note that both MJN and Chris responses also correct and sound.
SFK

 

[Tracey0273]

Thank you everyone for your help. I'm working today so plan to do this tomorrow but really appreciate all your help.

 

[Tracey0273]

Thank you to everyone who gave me advise on wiring the new stat. I managed to do it with your help