Replacing old thermostat with nest or tado

[thebeetlejuice]

Hi, i'm new here so please be gentle. I want to replace my old Satchwell TLX2259 thermostat with a new smart one either Nest or Tado. I'm not a sparky by no means but i do dabble a bit with changing a socket or replacing a light fixture etc.. i've watched some video tutorials online about how the wiring goes for these new smart thermostats and it seems rather simple. I can see the thermostat is wired but how its wired is putting me off. Next to the boiler i can see there is a socket box with a cable with 4 wires coming from the boiler with 1 blue, 1 brown, 1 earth and 1 black with brown sleeve, this would be Live, Neutral, Ground and the balck with brown cover is the Switch Live? And all of these are wired in a 8 slot connector block with what i am assuing is the cable from the thermostat which has 4 wires, 1 Red with brown sleeve, 1 Yellow with brown sleeve, 1 black and 1 green, i know the black is neutral and green is ground but is i can't tell which of the other 2 is the Live and which is the switch live? Would it be easier just to get a wireless one and connect the 1 cable with 4 wires that comes from the boiler to the new wireless receiver and disconnect the other cable from the connector blocks and end the circuit and possibly if easy enough remove it from the wall alltogether?

 

[flameport]

What kind of boiler is it - combi, or separate hot water cylinder?
Is there a separate programmer or timer?

 

[thebeetlejuice]

What kind of boiler is it - combi, or separate hot water cylinder?
Is there a separate programmer or timer?

The boiler is a combi boiler, brand Alpha model CD25X.

 

[ericmark]

Looking at the instructions it seems no option to use OpenTherm it is a simply on/off,

so the thermostat is fitted to stop the boiler cycling, or turn it off as set times, the basic instructions are to fit the wall thermostat in a room with no alternative heating or outside doors on the ground floor, most homes no such room, so some sort of compromise is required.

There are open plan homes where a single wall thermostat can work, but most homes have doors, so what is wanted is a number of linked thermostats, and the easy way is to use linked TRV's. Tado allows this, Nest UK does not, only Nest USA allows multi-sensors, Nest UK was claimed to work with Energenie but I found the support has been removed.

The wall thermostat you show works well with TRV's, but not programmable, the Nest e is programmable and being battery powered lack of neutral is no problem, but seems you have a neutral so likely Tado is better option as I think Tado does have linked TRV heads, as does Hive, Wiser, Evohome, etc.

So the cost is really down to cost of thermostat plus at least one TRV head. The main point is to select the TRV first, then get a wall thermostat to match it. My TRV's are not linked, I have Energenie and eQ-3 and I found once fitted did not really need wall thermostats, but the eQ-3 bluetooth worked for me better than energenie, but reading reports it seems the Drayton Wiser TRV is a smart device and works out when to heat the room.

So I would say look at the TRV's first then get a wall thermostat to match.

 

[CBW]

I would go with Tado personally, or any other smart thermostat. No issue with Nest, but you may struggle for the 12v supply as running it in the existing may cause issues with induced voltage, unless you use the plug or the Nest E.