Cooling staging

[Tor12]

How can I adjust the temperature stage up between cooling stages? I’d like to run my unit a little bit longer on cool stage 1 rather than jumping to Cool stage 2 after a couple minutes. And how can I tell it’s running on cool stage 1? 

[CoolingWizard]

@Tor12 , the thermostat itself is what makes the decision to switch from Stage 1 to Stage 2.  If the set point is greater than 2 degrees from the current room temperature, it will activate stage 2 cooling.  Once it the room temperature gets within 1 degree, it will switch back to stage 1 cooling. Do me a favor and get me the Model Number if your outdoor unit.  I want to look on the cooling operation protocols.  

AC Cooling Wizard

[Tor12]

AC Cooling Wizard 

I’m in the hvac field- have a High Eff 2-stage carrier RTU, I’ll follow up w nameplate info. Y1 energizes unloaded comp w/ 1st stage fan. Y2 loads comp and hi speed fan. Everything works fine as I see it, I would just like to know the time delay between stages up and down and possibly adjust as needed to fit my needs. 

[Tor12]

AC cooling wizard, 

Not sure if you’ve had an opportunity to look into my question. I ca assure you the wiring is correct and the RTU is running as the T-stat commands. On my old t-stat I was able to adjust the timing for stage up, similar to PID. Not sure if Nest offers a technical manual to help w/ this adjustment. Seems to be working better as the t-stat learns our home but still starts on 2nd stage every once in a while. I see the peak on my solar graph which is consistent w the cooling algorithm. 

[CoolingWizard]

@Tor12 , in accordance with HVAC standards, the thermostat initially initiates cooling stage 1. If the stage 1 cooling does satisfy the call for cooling or is the ambient temperature continues to rise, and the timer1 expires, the  thermostat will energize Y2 and activate stage 2 cooling.  Timer1 is set to allow the system to run and stabilize and in most systems this is set at 25 minutes.  However, is the ambient temperature rises 3 degrees after initial call for cooling, the stage 2 call will immediately be initiated.  You can see the timings typically listed in IM of the AC outdoor unit.  Sometimes manufacturers place lockouts in the control board of the outdoor to limit stage changes.  There is not a user changeable timer value in the Nest Thermostat 

AC Cooling Wizard 

[EdmondB]

Hello  Tor12,

The Nest thermostats use their Time To Temperature algorithms to estimate how long it will take to warm or cool your home to a specific temperature. If your system has more than one stage of heating or cooling, this estimate helps your thermostat know when to turn on different stages to reach the target temperature efficiently and on time.
 

If your system’s first stage of heating or cooling won’t reach your desired temperature in a reasonable amount of time, your Nest thermostat will turn on additional stages of heating or cooling to ensure that you’re kept comfortable.
 

Stage 2 Cooling will show in the Nest thermostat display when second-stage cooling is activated on your HVAC unit.

Thanks for the help, @CoolingWizard.

Let me know if you additional questions.

Best,
Edmond

[Tor12]

Thanks Edmond B, 

As an HVAC tech, is there additional support available for field programming modifications? 

[EdmondB]

Hi there,

We don't have any direct support for field programming modifications, but we have our Engineering team where you can submit feedback on our Google Nest Product to make it better and more user-friendly. Here is a link on how to file feedback.

Thanks,

Edmond

[Markjosephp]

Hello folks,

Thanks for the help here, Edmond.

@Tor12, I'm checking back in — how's it going? Still need our help?

Regards,

Mark

[Tor12]

Edmond and Mark, thanks to both of you for your follow up. 

[Jenelyn_O]

Hey Tor12,

I just want to check if you still need help, Please let us know as we'll be willing to assist you further.

I appreciate the help, @CoolingWizard, Edmond, and Mark.

Kind regards,

Jenelyn

[Tor12]

Jenelyn_O thanks for the follow up. We can close this thread. Thanks to everyone for the support. 

[Jenelyn_O]

Hi there Tor12,

Thanks for keeping us in the loop. Please feel free to create a new thread if you have any questions or concerns, as we'll be willing to assist you from there. I'll be locking this thread now.

I appreciate the input, @CoolingWizard.

Cheers,

Jenelyn