New to Nest

[Runnernpa]

Hello All,

I recently had a brand new heatpump system installed in my home that previously had no A/C. We do our heating with a boiler system that has its own thermostat. The contractor that installed  my new system along with the new Nest Learning thermostat tells me that the Nest thermostat can’t incorporate the controls from the original heating system. Is this a true statement? Or is there someway that I can use the * terminal and the Rh terminal to control the old system. We would like to use the heatpump until the temperature drops below 45 or so and the use hot water system after that. 

[Ryan_G]

Hey Eytan,

Thank you for reaching out and sorry for the delay.

We could further check it by getting a photo of your current system wiring. 

Also, let us know which Nest Thermostat you're using.

I hope to hear from you soon.

Regards,

Ryan

[Ryan_G]

Hey Eytan,

I just wanted to follow up and see if you are still in need of help? Please let me know, as I would be happy to answer any questions you may have.

Best regards,

Ryan

[Ryan_G]

Hey there,

Just wanted to jump in here to check to make sure that you saw our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Have a great day.

Best regards,

Ryan

[Runnernpa]

Hi Ryan,

so sorry, I was trying to reply to the emails you were sending. 

I tried to attach a photo, but can’t seem to figure out how. 
Rh is the 24v coming from my boiler and W2 is the signal back to the zone valve to open.  

What isn’t shown in the picture is the white wire coming from the 8kW electric emergency coil inside the indoor AHU; that is in the wall. 

The thermostat is a 3rd generation learning thermostat. 

Scott Coates

[Ryan_G]

Hey Scott,

Thanks for your reply.

The Nest Learning Thermostat can handle upto 2 stages of heating and cooling. In your case, you mentioned that it is a heat pump, we usually use the * for emergency or auxiliary heating/cooling and OB terminal for the heat pump zone valve to operate. 

Once your Rh wire is connected, you could try to connect the other wire to the * terminal then go to settings > equipment and select your heat type and source. This will give the Nest Thermostat an idea of what kind of heating or cooling system you're using.

Let me know how it goes by replying to this thread.

Best regards,

Ryan