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Not "easy" install - no Power with C wire connected

Trystero
Community Member

‎11-23-2023 03:27 PM

After several days - and many hours - I have put my old thermostat back on the wall as a cold night approaches and the Nest Thermostat completely failed us.  After initial install on a two wire/heat only (R and W) Google told me I had low power and needed a Google Power Adapter which they kindly sent for free.  In the meantime the Nest worked fine for a week even though it gave me a N error - low power issue.  When I came back to the house (2nd home) with the power adapter I had studied up and realized I just needed to add a C wire.  My wiring had a third unused wire.  So I connected that to the C 24v screw on my control board and connected the other end to my nest.  It worked but was now flashing NO POWER once in a while.  In SETTING/EQUIPMENT it gave me a N code - but it connected to internet just fine and I could control heat.  When I went to wiring I could see all three connected wires and when I went to power it was moving around between 29v and 32v.  All the power settings showed connection.  But still the N error and the occasional NO POWER.  In the midst of this C wire install - I got low battery warning so changed batteries.  I used the app to re-set the wiring configuration.  It controlled the heat last night just fine.  But as a 2nd home I don't want to find out I had been on battery power and have heat go out when I'm hours away.  Trying to remedy this - today I disconnected C wire and installed Google Power Adapter.   Then things went kerfluey.  It was flashing NO POWER constantly and wouldn't let me do anything.  I checked my install and all was correct.  When I checked wiring it didn't show red connected.  I re-checked my red connections.  Still nothing.  So I pulled the power adapter and went back to my C wire configuration.  (BTW - I turned off system each time and carefully wired all changes.). This time the unit stalled out in STARTING UP.  I manually reset by pulling batteries but when replugged in it flashed NO POWER and gave me no controls at all.  Beaten, I yanked it and put on the old thermostat, turned system on and set it to a cozy 70 degrees.  The furnace roared to life.  Extremely underwhelmed with Nest.  Can anyone offer advice?  I am an above average handy man and can't stomach paying someone to install something so simple as a thermostat.

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zoeuvre
Community Specialist
Community Specialist

‎11-27-2023 08:54 AM

Hi Trystero, 

 

Oh no! I'm sorry to hear about the difficulties you've experienced with the Nest Thermostat installation. Installing a thermostat can sometimes be challenging, especially when dealing with power issues. I understand your frustration, and I hope these suggestions help you resolve the problem with your Nest Thermostat installation.

 

  1. Make sure to recheck all wire connections to ensure they are properly inserted in the appropriate terminals. Ensure that no wires are loose or frayed.
  2. It’s also important to ensure that your Nest Thermostat is getting enough power since you mentioned low power issues. The C wire (also known as the common wire) runs constant electricity to the thermostat for the latter’s proper operations. Ensure that the C wire is properly and tightly connected to the thermostat and the HVAC system.
  3. Reverify the C wire connection on both ends and confirm whether it is correctly fixed. In addition, you can use a multimeter to test whether you are receiving the correct voltage at the C wire connection point on the HVAC control board.
    • Set the dial to 200 VAC.
      • If the multimeter doesn’t have a 200 setting, choose 100 or 250 VAC.
      • The general rule of thumb is don’t set it too high (500+) or too low (50). Place the red lead on the R wire.
    • Place the black lead on the C wire.
    • The normal readout should be somewhere between 20 and 30 V (24 V is most common).
  4. Try to do a factory reset on the Nest Thermostat if you haven’t already. This will assist in the resolution of any potential configuration problems. Perform a reset on Nest Thermostat following the instructions and then go through the setup process again carefully following each step.

 

Let us know how it goes.

 

Best,

Zoe 

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