Wiring

[SchummerNest]

No C wire. 4 wires in wall. R & W go to current old thermostat. Another set of R and W connect to what is labeled as "Clock Terminals". These power an analog clock on old thermostat (1970's Honeywell).  How Can I connect either a Nest or Nest Learning Thermostat to this config?

[GunterArango]

The Information you shared above is great. I have been reading all you shared here. In this, you explained everything very well. If I want any further guidelines we will contact you here https://www.googlenestcommunity.com/t5/Nest-Thermostats/Wiring/td-bik-p/136225

[SchummerNest]

Are either of the 2 remaining wire good to use as a "c" wire?

Where would I connect them? I did install the Nest "Learning" with just the 2 wires but am afraid the (lithium) batteries will drain quickly.  2 other wires now connected to nothing...

[Patrick_Caezza]

The clock terminal wires will not be used as they just supply power to the clock in your original thermostat. You will need to tape them off.

The other two wires will control your heater/boiler and depending on your heating system you might need an external relay and the Nest Power Connector.

Here is possible wiring for just the Nest Power Connector with an external 24VAC transformer.

 

[MelbaDT]

Hey folks, 

Thanks again for answering, Patrick_Caezza. Appreciate also your inputs, GunterArango. 

SchummerNest, I'm jumping in there to ensure everything is good to go. Let us know if you have more questions. 

Best, 

Melba

[SchummerNest]

I have just connected the R and W wires to the Nest, and seems to be working. At some point I expect the batteries to drain. I noticed a charging port on the Nest Learning thermostat. Can I just 'manually' recharge the batteries when the time comes? I could have the HVAC guys hook up the Nest power connector at some point.

[MelbaDT]

Hey SchummerNest, 

Got it and yes, if the battery will drain in the next few weeks or days, you have the option to go ahead and charge it manually via the USB port while waiting for an HVAC technician to work on a permanent fix. 

Best, 

Melba

[MelbaDT]

Hey there, 

Checking back in should you still need our help here. 

Best, 

Melba

[MelbaDT]

Hi, 

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.
 

Best, 

Melba