Wiring new boiler thermostat

[SantoR]

Goodmorning, I'm trying to replace my old mechanical thermostat with a Moes Wifi thermostat, but i'm struggling to wire it.
Can you please help me?
Thank you
Santo

20201020_221437

• SantoR
• 24 Oct 2020

Siemens RAA20

 

[CBW]

More information required please, like a better photo of this one and a photo of moes wi-fi one (there’s several types iirc).

 

[SantoR]

 

[SantoR]

 

[CBW]

Ok, do you have a multimeter or two pole voltage tester? You need to establish if the grey wire is neutral - your moes requires a permanent live an permanent neutral.

 

[SantoR]

I don't have any voltage tester, if can help the grey one was not connected to the previous

 

[SantoR]

 

[CBW]

Not really, as the previous one might not have needed it. The moes requires a permanent live and permanent neutral connection (L and N). Can you trace the wire? Can’t really assume it’s a neutral connection. Once this is confirmed it’s straight forward from there.

Edited: yep, all you have there is live and switched live.

 

[ericmark]

Brown and black to 1 and 2. But as to 3 and 4 it all depends on if 24 volt or 230 volt control. Boilers have 4 ways to control them.
1) Return water temperature.
2) 230 volt AC on/off
3) Extra low voltage on/off normally around 24 volt.
4) Analogue control normally 0 - 48 volt
Some boilers have all options, some only one. But even the boiler make and model often does not help, it could be either 2 or 3, but we have no idea which. If 230 volt there is a chance the grey can be connected to neutral.

Try with a neon screwdriver, not a good test, but if it lights then you have a chance, if not then likely 24 volt.

As far as I am aware the only wall thermostat with wifi that is 2 wire only is the Nest E.

 

[SantoR]

Not really, as the previous one might not have needed it. The moes requires a permanent live and permanent neutral connection (L and N). Can you trace the wire? Can’t really assume it’s a neutral connection. Once this is confirmed it’s straight forward from there.

Edited: yep, all you have there is live and switched live.

So how the connection should be?

 

[SantoR]

Brown and black to 1 and 2. But as to 3 and 4 it all depends on if 24 volt or 230 volt control. Boilers have 4 ways to control them.
1) Return water temperature.
2) 230 volt AC on/off
3) Extra low voltage on/off normally around 24 volt.
4) Analogue control normally 0 - 48 volt
Some boilers have all options, some only one. But even the boiler make and model often does not help, it could be either 2 or 3, but we have no idea which. If 230 volt there is a chance the grey can be connected to neutral.

Try with a neon screwdriver, not a good test, but if it lights then you have a chance, if not then likely 24 volt.

As far as I am aware the only wall thermostat with wifi that is 2 wire only is the Nest E.

I'm going to buy a neon screwdiver, and i'm gonna check, also if it can help the boiler making is Ideal mini

 

[ericmark]

A neon screwdriver is not what you want, I only said that in case you already had one. If I have found correct installation manual it does seem it is 230 volt control, but some way some how you need to test.

 

[SantoR]

A neon screwdriver is not what you want, I only said that in case you already had one.

No I don't have, so can you tellme precisely how to try to connect them? Thank you

 

[CBW]

Personally I would go out and purchase a multimeter, and possibly some connector blocks. Place the wires into the separate connector terminals and test between the live (brown) and grey (possible neutral). If 240vac then it can be assumed that the grey is neutral, as we already know the brown is a live, possibly 240vac. Once this is established we can state which wires go where. If you don’t test, we can’t give the best advice. Multimeters are inexpensive, £7.49 from Screwfix.

 

[SantoR]