Need help installing Nest Learning Thermostat 3rd gen for 7 wire system (C,G,Y,R,W1,G2,G3)

[SaidEhrlich]

I live in an apartment building. The system uses a fan coil. I'm upgrading from a Honeywell thermostat TB7100A1000 Multipro T-Stat. 
I tried installation through the app; until it said I needed a pro. 
Wires: C,G,Y,R,W1,G2,G3
A diagram on the fan coil labels this wires as:
C - Neutral
R - Power (L)
Y - Cooling (Y)
W1 - Heating (W)
G3 - High Fan (GH)
G2 - Medium Fan (GM)
G - Low Fan (GL)

[CoolingWizard]

With that configuration, you will need a Nest Learning Thermostat, Gen 3.  Only the learning thermostats can deal with a 3 speed fan.  Remember the thermostats and a programable controller.  So since you have the 3 fan speeds, 1 heating mode 1 cooling mode, the Nest Learning Thermostat will work.  Here is the Google Nest Compatibly checker. 
Your Honeywell TB7100A1000 was designed to be compatible with PTAC systems.  A PTAC are those packaged heat pump units you often find in hotels hence the support for 3 fan speeds.  With conventional HVAC systems, there is generally only two speeds used.  High for Cooling and medium for heating.  

The AC Cooling Wizard

[SaidEhrlich]

Hi! thank you for the reply. The model you mentioned is what I have (Nest Learning Thermostat Gen 3). The guided setup (through the app) recommended I get help with wiring. 

Do you think the connections below look correct? I do not know where to connect G2 and G3.
Existing wires on the left / Nest wire plate on the right
C / C
G / G
Y / Y1
R / Rh
W1 / W1
G2 / ?
G3 / ?

[CoolingWizard]

Personally, I have never installed a Nest thermostat with 3-speed of fan.  I know that if you put the G2 wire in *, it will consider it a  dehumidifier, it you put the G2 in W2 it will consider it a Stage 2 heating. Can you tell me what HVAC make and model equipment you trying to control? 

The AC Cooling Wizard

[SaidEhrlich]

Yes definitely. Thanks again for taking a look at this. Below is the schematic posted on the fan coil unit. The make is Enerzone, but I can't find a model number on the unit, and it's not evident on the schematic.

[CoolingWizard]

I am a Google pro as well as a Nest pro and I am going through all the documents. I can find right and I am trying to find any documentation to tell me how to wire up three speed motor to the nest thermostat. Unfortunately everything I’m finding tells me that the nuest will only support a single speed fan, although if you put it through the compatibility checkered says yes I can support G1 G2 G3, but you’ll need a nest pro to install it. So now I’m trying to find the documentation and I’m not having much luck so far. 

The AC Cooling Wizard

[SaidEhrlich]

Thanks again. I'm trying to look again, but as you mentioned - not having luck. If there is any other info I can look up from the system that would make this easier please let me know.

[CoolingWizard]

As soon as I can find something, I will let you know.  I submitted and Nest Pro VIP request to see if one of the engineers will give the answer we need.  

The AC Cooling Wizard

[SaidEhrlich]

I'll wait for your reply. Thanks a lot!

[Patrick_Caezza]

@SaidEhrlich 

What you want to do is easy. A wiring diagram for controlling a 3-speed fan is on page 17 of the Nest Pro Installers Guide.

Try this,

Neutral to C

Power to Rc

Cooling to Y1

Heating to W1

High Fan to *

Medium Fan to Y2

Low Fan to G

[CoolingWizard]

@Patrick_Caezza , @SaidEhrlich 

Thank you Patrick.  I too received a response from the VIP team that pointed me to the pro installers guide page 17. Now there’s some other things you will have to take a further step as well. Once you add those wires as the page 17 tells you to put the G2 G3 in. Once you do this, you reattach your display and the system is going to tell you that your wiring has changed. You’re going to have to go into Settings > Equipment > Pro Setup and define the function of the wires. When you enter that pro set up area, you will see a picture of the back plate with the wires attached and some of the wedges will be yellow instead of green.  You will need to rotate to dial to a yellow wedge, and then you will have an opportunity to change the function of that particular wire. Y2 will default to Stage 2 Cooling.  Change it to G2 Fan. The * will default to humidifier change that to G3 fan.  Now once that is done, all wedges are Green. Your ready to test. 

Test the Fan by using your Nest App, open the app, select your thermostat, then select the Fan at the bottom. You should see a window one up and the three fan speed section on top. Choose a speed, choose a duration and tap start. Optionally, when you complete the set up, you’ll have an opportunity to test each fan speed in the test window.

Ken, The AC Cooling Wizard

[SaidEhrlich]

@Patrick_Caezza, @CoolingWizard 
Thank you both so much for your help. I got the thermostat wired, installed, and working. 
I have only one question left. I had to adjust the configuration for W1 - heat. 
I read online some people had some strange behavior when setting the source to "electric".
The configuration I have now is: source = gas, delivery type = forced air, fan = activate.
The building uses a central heating system - I can find out what kind it is (boiler or gas?). Does it make a big difference for my setup?
Thank you very much!

[CoolingWizard]

Your system is fed by water from the building.  I imagine they change it to cold water in the summer and hot water in the winter?

The AC Cooling Wizard

[SaidEhrlich]

Thanks again! system is setup and working well. Cheers!

[Markjosephp]

Hello folks,

I wanted to ensure that everything was covered here.

Thanks for looking into this, @CoolingWizard and @Patrick_Caezza.

@SaidEhrlich, I'm glad to hear it was sorted out! If there’s anything else we can help you with, please let us know. Otherwise, this thread will be locked in 24 hours.

Regards,
Mark