Stage 2 Heating doesn't engage while preheating

[BillC3]

My Nest Thermostat is set to lower temperature to 58 degrees at 10:00 pm and back up to 71 degrees in the morning at 8:00 am.  I also have it set to preheat for no longer than 1 hour so preheating won't start any earlier than 7:00 am.  What I am noticing on very cold mornings is that preheating starts at 7:00 am but Stage 2 heating doesn't kick in until 8:00 am.  I've included a link to a screenshot of my heating history. for the past 5 days.  For January 31 through February 3, note that when preheating  starts at 7:00 am, the color is light orange.  At 8:00 am the color is dark orange indicating Stage 2 heating is engaged.  For January 30, preheating again starts at 7:00 am but temperature reached 71 degrees before 8:00 am and Stage 2 heating was never necessary.

Link to heating history: https://drive.google.com/file/d/1-cX5IL9Kg0R-5ZDbbqSJBb1X8kDjA0ps/view?usp=sharing

1. Does preheating not look to see  if  stage 2 heating is necessary?

2. My Nest display indicates "Preheating" when the furnace turns on at 7:00.  "Preheating is also displayed  on the thermostat itself.

3. Here is a picture of my thermostat wiring if  that  helps:  https://photos.app.goo.gl/CjZocoEjoJGmsZpA7  

[Jenelyn_O]

Hi BillC3,

Thanks for reaching out — I'm sorry for the delay. I just want to follow up if you're still encountering the issue. Please let me know as I'll be willing to assist you from here.  

Best,

Jenelyn

[BillC3]

Hi Jenelyn,

Here's what I've done.  I got it  to work by turning off "Early-on" and changing my schedule to one hour earlier. 

I originally had my thermostat scheduled for 71 degrees at 8:00 am and "early-on" set to run no more than one hour.  On cold mornings with that setting, the heater would turn on at 7:00 am and run for an hour.  At 8:00 am, the heater stage 2 would kick in and run until it reached 71 degrees.  Now, I've turned off "early-on" and changed the schedule to  71 degrees at 7:00 am.  It immediately runs stage 2 heating at 7:00 am and is pretty close to 71 degrees at 8:00 when we get up.  I have "Auto-Schedule" on Learning and "Time-to-Temp" on  Ready.  It's my contention that  with these settings, Stage 2 heating should have turned on at 7:00 am with "Early-On".  I  think  it's either a bug or a design flaw.  What do  you think?

[Jenelyn_O]

Hey BillC3,

Thanks for the update and for being a step ahead of us. Could you please check if you have an Eco temperature set on your Nest Thermostat? 

You can follow the steps below to check your Eco:

1. Go to your thermostat Quick View menu.
2. Select Settings.
3. Look for Eco.
4. Check for Heat to and Cool to.

Best,

Jenelyn

[BillC3]

Min: 64; Max: 78

[Jenelyn_O]

Hi there,

Thanks for that information. If you have a schedule set on your Nest Thermostat, I suggest turning off both of your Heat to and Cool to for your Eco, as it can bypass your thermostat Schedule. After that, monitor your thermostat behavior if the issue persists. 

Please let me know how it goes.

Best,

Jenelyn

[BillC3]

I did as you suggested - turned off Heat to and Cool to and I turned  Early-on back on.  It did not correct the problem.  The Early-on setting turned the regular heat on for an hour.  When the scheduled time for 71 degrees arrived, Stage 2 heating  kicked in.  I've now reverted back to my original settings - turned off Early-on and reset the  ECO settings to Min: 64 and Max: 78.

[zunkman]

I've noticed on my system that Stage 2 only kicks in after Stage 1 has been on for EXACTLY (and I mean "exactly") one hour.  Maybe yours is the same.

There is, of course, an exception.  If I'm AWAY, and come home, and the house is more than 3 degrees below my HOME setting, the furnace goes directly to Stage 2.

[zoeuvre]

Hi everyone,

I wanted to check and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.

Thanks,

Zoe

[Jenelyn_O]

Hi folks,

I wanted to follow up if you still need help. Please let me know if you’re still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

I appreciate your help, Zoe.

Regards,
Jenelyn

[Jenelyn_O]

Hi there,

We haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you need assistance or want to discuss topics, feel free to start a new thread.

Best,
Jenelyn