This is used, for example, if the 'stat is locaqted in a poor place that might suffer from draughts - since the 'stat will be senseing air that is colder than in the rest of the room, this control will allow you to alter the displayed temp to represent the main room as opposed to the 'draught'.

What colour is used for what, would have been chosen by the original installer and varies from installation to installation. But you also say "New Build" it is required to have zones in new builds, all that is required is TRV heads, but often one finds zone valves, but the Nest system does not seem to be designed to work with zones, EPH do an OpenTherm thermostat which can be set as Master/Slave but I know of no others, often the zone valves need removing to fit the likes of EvoHome or Wiser.Read more about the condition New: A brand-new, unused, unopened and undamaged item in original retail packaging (where packaging is applicable). The 103 third parties who use cookies on this service do so for their purposes of displaying and measuring personalized ads, generating audience insights, and developing and improving products. Equally though it can be programmed for completely different times every day of the week making it much more customable for individual lifestyles.

It's attractive, and there is an openable cover which normally hides most of the buttons, except the ones needed for everyday functions. I bought this thermostat controller as a temporary replacement while my other thermostat was repaired. This will also need wiring changes as right now, the wall thermostats control the opening of the valves.Occasionally, nothing seems to be able to turn it off- not lowering the set temp, switching to manual, or even turning the unit off.