Tempetature drops

[Tessav]

I have underfloor heating. I set my thermostat in this cold weather to 20 degrees (large open planned living dining area).  Initially it is good, nice and warm and floor is also warm. After a few hours, although thermostat still says 20, room turns cold and no floor heating. Seems to be cold air coming from somewhere 

What is going on?

[zoeuvre]

Hi Tessav, 

Yikes! I'm sorry to hear that the temperature dropped after you called for heat with your thermostat. Let me take a look at this for you. A few questions: 

• Are you located in North America or Europe? 
• What type of Nest Thermostat do you have? 
• Is the Nest Thermostat newly installed?
• Did you use the Compatibility Checker tool to confirm the thermostat's compatibility. 
• Does the thermostat screen indicate that it’s actively calling for heating? 
• What type of furnace do you have? (gas, electric, etc.)
• When did heating last work? 
• Did heating ever work with the Nest thermostat? 
• Did the heating work with the previous thermostat? 
• Did you turn off the power to the HVAC system? 
• Did you recently turn off any breakers?
• Have you recently experienced a brownout or blackout? 
• Is there a light switch near the heater that controls an outlet? 
• Did you select the correct fuel type? 
• Do the LED lights blink on the HVAC control board? If yes, locate the light. 
• When was the last time you changed the furnace's air filter? 
• Have you experienced extremely cold weather lately?
• Is this the first notable temperature drop of the year in the area?

I'll look forward to your response. 

Best,

Zoe