Smart room thermostat

[stem]

Interesting. The diagram you have is different to mine. I guess the difference is the '2' on the end of the part number. Rather unusual though normally manufacturers stick to the same configurations across their range of products.

Therefore, NO and NC are transposed In which case you are correct. Terminal 3 will actually be NO and therefore you should use the NO terminal of your new thermostat which would make more sense and solves the riddle. Well spotted.

 

[Peterba]

Cheers. We got there in the end.

Excellent helpline! How are you funded?

 

[stem]

I have a day job but I can be flexible in my working times. And there can be quite a bit of waiting around time to kill especially when travelling. Hope you get it working OK, there's still the set up to get through.

 

[Peterba]

I have had an electric floor version of this unit and it was easy to set up and excellent to use.

I’ll let you know how I get on. Will be Wednesday before I do it now.

 

[stem]

OK that would be good thanks. I don't think anyone has yet reported back that they have managed to get similar devices working 100% as they should. Hopefully you will be one to do it.

 

[Peterba]

Aaaahg.

Looking at the circuit of the new device, when the relay closes it puts a connection to the Neutral wire!!!!!!

They way it’s wited now, when relay closes it gives mains Live.

???????

Can you see a solution

 

[Peterba]

It just seems by the circuit diagram that the internal link is to the neutral.

 

[stem]

Not quite sure how you come to that conclusion. Are you referring to the connection circled in red?

If so, that N is external of the thermostat.

The device below the red circle is a MOMO valve (Motor On, Motor Off) they are used in certain parts of the world but are almost as rare as hens teeth in the UK. The MOMO valve is shown with a Live to open (NO) and a Live to close (NC) connection both of which come from the thermostat. But because the MOMO valve contains a motor it also needs a neutral to operate which in the diagram above is supplied externally and not through the thermostat.

If you are referring to another diagram that I haven't seen when you refer to 'circuit diagram' can you post what you are looking at please.

 

[Peterba]

No, that’s it. I had a vision that it was this Nuetral connection that put through. Thanks for the explanation.

When I did my degree ( and service later) it was still thermionic valves and just going over to transistors so the brain is getting a bit slow I’m afraid and no idea on these devices. So thanks! Again.

 

[Peterba]

Ha, guess what? I fitted device yesterday and the screen remains blank. Not a wiring issue but a faulty device. I tested it just with power connected to a mains fly lead and just a blank screen. Anyway in process of getting a new one - if they offer cash back do you know a suitable device I could use instead??

 

[stem]

Whilst I have fitted and helped others to fit many smart thermostats, I don't actually have one myself as they don't offer me personally any tangible advantages. So I can't really comment on their functionality. Nest / Hive are the most popular on here with a few Tado's thrown in for good measure. They all seem to be reliable & without operating issues.

Of the three, from the feedback I have from users, Nest seems to be the one that gets the most compliments because of its looks and additional features. Notably: Open Therm, (doesn't work with multiple zoned installations though) & its learning capability. No complaints about Hive though. It is generally the easiest to wire in, but does need an additional hub connecting to a wired broadband connection. Not had much feedback on Tado, probably because I've not been involved with that many Tado installations.

I would avoid buying any cheap product from an overseas shopping website, they are not always ideal for installation to UK systems, and seem to be prone to problems and have poor or non existent technical support.

 

[Peterba]

Ha, put it on a fly lead and connected it to App. I then turned it on from App. It was in off state and so could not be brought to life other than a sequence of switch events or by the App.

Works absolutely fine so thanks.

Money well spent on device.