Hostmann to Nest Learning Thermostat

[MalteseLR]

I currently have a Horstmann CentaurPlus C27 attached to my gas boiler. The system has no thermostat. I have purchased the Nest Learning Thermostat which I wish to have portable around the house. I’m noticing that I’m missing something here. I guess I need a unit that replaces the current controller and this unit receives the signal from the Nest. Does this make sense or have I got it completely wrong?

 

[CBW]

It doesn’t make sense to me. A Nest isn’t really portable, but think you can use app control. What are you missing?

 

[jado84]

As in the unit you wire into your boiler? In Nest speak, this is called the Heat Link.

 

[ericmark]

There are three types of Nest thermostat in the UK, Gen 2, Gen 3, and e. The Gen 2 did not have opentherm, Gen 3 and e do, Gen 3 is mains powered, e is battery powered, non will connect to temperature sensors they have only been released in USA and their Nest is completely different to ours.

Nest controller is portable to some extent, the controller is the bit which measures the temperature, and has a display, and can be used to set the system, it can either be powered from the 12 volt DC from the heat link (Gen 3) or from a cradle which is USB powered, it has an internal rechargeable battery, but it does not last long when power fails.

The Nest e is about the only thermostat where the base is battery powered, the Nest Gen 3 has volt free contacts so is quite flexible, if the 12 volt from the heat link is used, this also carries the information rather than being wireless.

I used Nest Gen 3 as only two wires main house to flat where the boiler is, and wanted to control DHW and CH from main house, however the adverts said it worked with Energenie MiHome TRV heads, and it does not, well the both use same app, but schedule changes and turning dial does not work.

So rather a disappointment, and the geofencing has no control, except for comfort and Eco settings, can't set distance from home when it turns on, most of the features had to be disabled.

The heat link as a line of 13 terminals from memory, so only just enough room, so needed to mount a wiring centre (junction box) under the heat link to connect all the wires. But with my set up one boiler serves both main house and flat hence the old thermostat in the picture.

It works, but I would not recommend it, today the whole idea is only heat areas when required, so we want linked TRV heads, at least in a couple of rooms, in the main these do a good job, and cheap enough at £15 each, well they were in 2019, but they don't link to main thermostat, so unless boiler running they can't control the room.

Even Hive has linked TRV heads, although they stop working if room with Hive in exceeds 22ºC but EvoHome, Wiser, Tado all have linked TRV heads, Nest is the odd one out, in USA they have temperature sensors so it can monitor 4 areas, but not released in UK yet.