Nest Gen 1 - Unusual Wiring Need

[BoatGuyBill]

I just got a Nest Thermostat - Gen 1.  I want to connect it to my boat’s furnace, which requires simply an on/off relay connection.  I have a 24v AC source for the thermostat.  How do I get a simple single-pole relay output from the Nest?  Thanks!

[CoolingWizard]

The Nest thermostat can simply make the connection between R and W and not need a 24 VAC power.   However without WiFi for the nest, it has little value add.  And will recommend we did a way to disable the WiFi chip and software to make the batteries last longer.  

The AC Cooling Wizard

[Patrick_Caezza]

I'm guessing that when you say Nest Thermostat - Gen 1, you mean the New Google Nest Thermostat with the mirror

The Google Nest Thermostat will not work without a C and R wire, and it must have Wi-Fi access to set it up.

There are a couple of methods that you can use to add a relay.

If your furnace has both a C and R terminal available, you can try this.

If there isn't an available C or R terminal, you must add an external 24Vac transformer.

[CoolingWizard]

@Patrick_Caezza I wish that example could be updated or at minimum annotated, because stand alone furnaces do not have an Rh or a W on their control system. What they have, and is well known, T and T. 

AC Cooling Wizard

[Patrick_Caezza]

@CoolingWizard 

It has terminals on the furnace labeled T1 and T2. One is labeled W/T1, and the other is R/T2.

It is impossible to cover every scenario possible out there.

[Jenelyn_O]

Hi folks,

I just wanted to jump in real fast to see if you saw the replies above and to see if you still needed some help on this or if you were able to get it sorted out. If you still need some help, just let us know and we'll be happy to continue helping.
 

I appreciate your help, @CoolingWizard and @Patrick_Caezza.
 

Regards,

Jenelyn

[Jake]

Hey BoatGuyBill,

I wanted to check in 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.

Best regards,
Jake

[Markjosephp]

Hi BoatGuyBill,

I'm checking in to make sure that you've seen our response. Please let us know if you have any additional questions or concerns before we lock this thread in 24 hours. 

Thanks,

Mark