Nest Support

Questions about Nest Learning Thermostat or Nest Protect: Smoke + CO alarm? We've got answers, videos, and plenty of resources to help you out.

What is True Radiant?

True Radiant is a Nest Learning Thermostat feature that keeps homes with in-floor radiant or boiler-and-radiator systems more comfortable. It reduces temperature swings and starts heating early so you get the temperature you want when you want it.

What is radiant heat?

Systems that use hot water can sometimes take a long time to heat up and cool down. In-floor radiant systems, which heat the home using hot water in pipes under the floor, can be particularly slow to react. Because radiant systems take so long to heat up, it can be difficult to set a schedule - you may need to start heating at 4am to get to the temperature you want at 7am. With other thermostats, underfloor radiant systems overshoot your target temperature by an average of 1.2ºC since radiant pipes stay hot even after the boiler has stopped heating.

Why does the temperature keep rising even after my heat has turned off?

How does True Radiant work?

True Radiant will make your heating system run like it always should have - according to your schedule. No more guessing and turning the heat on hours earlier than you need it. Tell the Nest Thermostat what temperature you want and when you want it, and True Radiant will take care of the rest.

With True Radiant, the Nest Thermostat learns how long your system takes to heat up. It will turn the heat on early to reach the target temperature, then turn it off early so your home won’t go beyond the temperature you want. For example, the Nest Thermostat may learn that to reach 20ºC, it should turn the boiler off when the room hits 18ºC - because the radiators are already hot and will take you the rest of the way to 20ºC. The Nest Thermostat will maintain that temperature by turning your system back on before the temperature gets too low.

How do I enable True Radiant?

True Radiant is enabled automatically. To confirm or turn it off, follow these steps:

  • On your Nest Thermostat, go to Settings > Nest Sense > True Radiant and choose ON to enable it or OFF to disable it.
  • On the Nest app, select the thermostat icon and then select Thermostat Settings (the menu in the top right corner of your screen.) In Thermostat Settings, select Nest Sense > True Radiant and choose ON to enable it or OFF to disable it.

*Numbers from the 2012 Nest Simulation