Google Nest 3rd Gen Learning t-stat compatibility

[THuff]

Does the Gen 3 Nest t-stat work with a variable speed compressor on the Carrier mini split unit !

[Houptee]

Mini-split units usually have a remote control and are not compatible with regular thermostats.

I think a few brands came out with a adapter box for Nest etc but you have to contact Carrier to find out if they have such a device for your model mini-split.

[Jhonleanmel]

Hey folks, 

We appreciate your help here, Houptee.
THuff, I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,
Mel

[Markjosephp]

Hello there,

Thanks for the assist, Mel.

@THuff, I hope you've seen Houptee's response, but I've got some additional information for you. Please take a look at this article and let us know if you need more help.

Regards,

Mark

[THuff]

Hello Mark,

If we wire the Carrier split system heat pump as suggested by Nest for a conventional heat pump the A/C comes on rather than the heat because of the reversing valve arrangement. We wired the Carrier split as a conventional heat and A/C but unfortunately the Nest t-stat brings on the backup heat way too soon. The heat pump will provide heat to zero degrees but the t-stat is bringing on the backup heat when the outdoor temp is in the mid 20 degree range. This defeats the purpose of the efficient heat pump and costs more money for the electric resistance heat. We were looking to set the Nest with a 4 degree differential rather than rely on the Nest algorithm to control the backup heat. We thought there may be a setting available in the Nest Pro setup but the Nest tech support for residential told us there is no such option. I was hoping someone might tell us another option. We are going to add an outdoor t-stat to control the backup heat and eliminate the premature operation due to an algorithm.

Thanks for assistance !

[Jenelyn_O]

Hi there,

@THuff, I saw your post and wanted to chime in. I'm sorry for the delay.

I just want to know if you still need help as I'll be willing to assist you from here. 

Thanks @Jhonleanmel, @Houptee, @Markjosephp.

Best,

Jenelyn

[THuff]

Hello Jenelyn,

I wasn't able to get satisfactory assistance from Nest support so I ordered auxiliary equipment for my installation. I am planning to install an outdoor-stat that will control a two pole relay. The outdoor t-stat & relay will prevent the auxiliary heat from from coming on at a temperature (any temps above 0 degrees) thus allowing the efficiency of the variable speed compressors to work.

If you know of a way to reset the Nest t-stat differential to 3-4 degrees rather than the 2 degrees from the factory it would be helpful and it may eliminate the need for the additional equipment. We have several split system heat pumps to install this year and we may just go with a different t-stat on future work for simplification.

Please let me know your thoughts.

Thanks,

Tim

[Houptee]

Are these systems "Mini-splits" or are they standard heat pumps?

In one of your posts you called them mini-splits which would be the ductless wall mount type systems.

If you have conventional heat pump with a air handler and electric backup heat coils then you have to set the heat pump balance or turn it off and set a specific outdoor temp that it will switch over to electric heat coils.

https://support.google.com/googlenest/answer/9248719#zippy=

[Jenelyn_O]

Hi there,

@THuff, I hope you already found the answer you're looking for provided by Houptee. If you have any questions or concerns, please let us know. 

Thanks @Houptee, for your assistance. 

Best,

Jenelyn

[Jenelyn_O]

Hi THuff,

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

Best,

Jenelyn

[Jenelyn_O]

Hi THuff,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Best,

Jenelyn