Heating-only thermostat has 2 red wires connected to red, 2 white wires to white?

[hvac_nimrod]

I have a 2-zone heating system (gas boiler) with 2 thermostats upstairs, one on my home's first level and one upstairs on the 2nd. I'm replacing 2 old Honeywell programmable thermostats with 2 Nest 3rd gen. Learning Thermostats. The upstairs thermostat only has 1 red and 1 white wire, so I know what to do for that installation. On the first floor, the old Honeywell thermostat has 2 red wires both connected to "R" and 2 white wires both connected to "W". Not sure why or how to do the installation with the Nest thermostat so that it works properly?? This is not a heat pump system and does not have A/C, just heat from a boiler with 2 zones. Can someone tell me what I do for this siutation? Do I twist the 2 reds and the 2 whites together and then run a single extension off of them to the "R" and "W" connector on the Nest? Thanks in advance for any help you can provide, I clearly am in over my head!

[Markjosephp · Accepted solution]

Hello hvac_nimrod,

Thanks for keeping us on the loop on how reconfiguring the wires to your Nest Thermostat worked. To answer your question:

The power line for your HVAC system is called the R wire. Since you only have one R wire (no Rh or Rc), you can connect your R wire to
either Rc or Rh on the Nest thermostat, both terminals are for power.

Please let me know if you have any other questions or concerns.

Regards,

Mark

[Markjosephp]

Hello hvac_nimrod,

Thanks for keeping up with our Nest Thermostats. Let's find out more about your HVAC systems wiring configuration. 

A few questions: do you have the picture of your previous thermostat wiring diagram? If possible, could you share us a clear copy? Also, what kind of Nest Thermostats you're installing? 

Keep me posted.

Best,
Mark 

[hvac_nimrod]

Hi, so I did say exactly what I had in my first correspondence.  It is a Nest learning Thermostat 3rd generation. I don't have a wiring diagram and described the issue. The old thermostat had 2 white wires connected to a "W" screw, and 2 red wires connected to a "R" screw. When I removed the old thermostat, I did see that one of the red wires and one of the white wires had been affixed with black tape on them, so one R and one W wire had black tape on it, the others did not. I don't know if that meant they were not in use or the main 2 wires? Anyway, when I ran the Nest setup configurator for the existing wiring based on this info, the Nest app told me to connect one white wire to W1, one red to RH and the other red wire to Rc and the other white wire to W2 AUX. After this, when I turned on my system power the Nest thermostat didn't have any power. I then switched the 2 reds and 2 whites to the opposite connectors thinking I had the wrong pair connected to the main connectors (W1 and RH). After the switch, the Nest started to work. The thermostat says on its display HEAT STAGE 2 and I'm not sure what that means. The Nest thermostat upstairs with only one set of R and W wires (connected to W1 and RH) does not show this message and functions normally. The thermostat in question here looks like it works, but when I turn the thermostat up, it is not calling heat to that zone and so my downstairs baseboard radiators are not heating up. Any ideas?

[hvac_nimrod]

Here are the images I can provide: 

[Markjosephp]

Hi there,

Thanks for getting back with more detailed information and appreciate your effort sharing the screenshots. That helped.

Since you have a Zoning System Gas boiler type and doesn't have a 2nd-stage heating equipment. It appears that you only need to have 2 wiring configurations for your Nest Thermostat. 

Give these steps a whirl:

1. For your safety, turn off the power of your HVAC system from the breaker.
2. On the Nest Thermostat, remove and leave the 2 wires that has a black tape disconnected.
3. Use only the other wires that has no black tape and insert them to W1 (white) & Rh (red) terminals.
4. Make sure to insert them properly and buttons should stay down.
5. Put the display back to its base.
6. Turn on the HVAC systems power.
7. Restart your Nest Thermostat.
8. If you have a Voltmeter, test the wires to check if they have voltages.

Please let me know how it goes.

Best,

Mark

[hvac_nimrod]

Thanks for your reply, Mark. It turns out I hired my local HVAC provider to come in an help me since I knew I was guessing at not getting very far. As it turned out, the tech guy did something I thought to do if not for my lack of electrical expertise -- he basically just wired the 2 reds and the 2 whites together and then made a short extension for each and used the W1 and Rc connectors and it started working superbly and pulling heat in the downstairs zone. So thank you and I'm set now. One question, the tech used the Rc connector downstairs for the red, I used the Rh connector upstairs for red. Both work fine -- and significant difference or negative about either setup?

[Markjosephp · Accepted solution]

Hello hvac_nimrod,

Thanks for keeping us on the loop on how reconfiguring the wires to your Nest Thermostat worked. To answer your question:

The power line for your HVAC system is called the R wire. Since you only have one R wire (no Rh or Rc), you can connect your R wire to
either Rc or Rh on the Nest thermostat, both terminals are for power.

Please let me know if you have any other questions or concerns.

Regards,

Mark

[Jhonleanmel · Accepted solution]

Hey folks, 

Thanks again for helping here, @Markjosephp. 
@hvac_nimrod, I hope you've got the answer you're looking for. If you're still in need of any assistance, feel free to let us know. 

Best,
Mel

[Jhonleanmel]

Hi everyone,

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 in 24 hours.

Thanks,
Mel