Using nest 1st gen have 2 wires red and white for heat - not sure to use “R” and “W” using nest 1st

[JimKellyCO]

I’m trying to install for a furnace (2 wires red and white) using Nest Thermostat gen 1. The install guide refers to “RC or RH” terminals on the Nest base but the only terminals are Y C W and G R OB.  I installed the red wire to the R terminal and the white wire to the “W” terminal.  The heat turns on and off but I’m getting an error power error message of N260 and it looks like the wireless shuts down once in awhile.  

Have I  connected the wiring to the right terminals?  Im wondering if this will work in the long run or if my system isn’t compatible. 

Thanks

Jim

[Patrick_Caezza]

@JimKellyCO 

The Google Nest Thermostat (2020) requires you to have a C wire when you only have two wires. If you don't have a C wire available you will need to use the Nest Power Connector and an External 24vac transformer and wire them like this.

[JimKellyCO]

Thanks Patrick. Just to clarify, this isn’t an HVAC system it is a heat only boiler system.   Does that make any difference. (I was told at Best Buy that it would work…)

[Patrick_Caezza]

@JimKellyCO 

Boilers tend to be harder to connect a smart thermostat to since they usually only have two wires for control.

Installing it like I posted should work just fine. I say should because nothing is guaranteed.

[CoolingWizard]

@JimKellyCO @Patrick_Caezza 

Boilers tend to be difficult because many they operate on a 750 mA control circuit or it is not necessarily easy to get to the 24 VAC Control wiring. 
You need to first determine how boiler control circuit power is provided and what the operational voltages are.

Some control systems ate simply a TT connection. That is connect terminal T to terminal T and the furnace will turn on. It’s not a voltage connection just a simple connection. Some of these type systems will work with voltages such as 24 V AC however some are not designed to have 24 V AC presented on TT. 
a trained HVAC technician can make that determination for you and that way you don’t accidentally take an approach that will damage the control system such as adding a transformer.

AC Cooling Wizard