Need help with thermostat power connector install for electric baseboards

[mkquesnel]

I was recently required to upgrade my 1st Gen Nest thermostat to a 4th Gen model. I had to make the change because I need to remotely control the thermostat. This function has been removed from 1st Gen thermostats. The thermostat has 2 wires (Rh and W) and controls baseboard heaters (with fans) in my living room dining room on a single circuit. Everything has been working well for several years. The baseboard heaters are on a 240 volt circuit and are connected to the thermostat through a White-Rodgers/Copeland Type 24A01G-3 Series 24 Level-Temp Control/Switch (essentially a switch and transformer?) with 18 Volt output to the control circuit (the Nest thermostat in this case).

After installing the new thermostat I received an error message N410, a voltage issue warning on the thermostat screen and a message saying I need to install a c-wire or a Nest Power Connector. I am not able to install a c-wire between the Level-Temp control and the thermostat without major demo/renos so I have ordered and received the power connector. After doing some research on line I have not been able to find any Level-Temp switches that have any control output of more than 18 volts. I thought it might just be possible to find a way to get 24 volts to the thermostat to solve the power issue.  However I spoke with Google Nest customer support (non-technical support) who told me that installing the power connector will “bump(?)” the voltage up to 24 volts which is required to maintain charge on the thermostat’s internal battery. The thermostat is currently working fine (but with the voltage issue showing) and the internal battery is at an acceptable level but, according to the support agent, will apparently degrade over time without a c-wire or the power connector. 
My issue is that I have not been able to find any wiring diagrams, either in the basic installation manual or the pro installation manual, that show me how the power connector should be connected to the Level-temp control. 
I would provide photos but have not been able to add them to this post. 
Any help with this would be appreciated and can submit photos by email. 

[mkquesnel]

Re-posting this with photos this time:

I was recently required to upgrade my 1st Gen Nest thermostat to a 4th Gen model. I had to make the change because I need to remotely control the thermostat. This function has been removed from 1st Gen thermostats. The thermostat has 2 wires (Rh and W) and controls baseboard heaters (with fans) in my living room dining room on a single circuit. Everything has been working well for several years. The baseboard heaters are on a 240 volt circuit and are connected to the thermostat through a White-Rodgers/Copeland Type 24A01G-3 Series 24 Level-Temp Control/Switch (essentially a switch and transformer?) with 18 Volt output to the control circuit (the Nest thermostat in this case).

LEVEL-TEMP CONTROL FRONT

LEVEL-TEMP CONTROL REAR

LEVEL-TEMP CONTROL INSIDE WIRING

 FULL SYSTEM WIRING (Black thermostat wire is Rh, white wire is W)

After installing the new thermostat I received an error message N410, a voltage issue warning on the thermostat screen and a message saying I need to install a c-wire or a Nest Power Connector. I am not able to install a c-wire between the Level-Temp control and the thermostat without major demo/renos so I have ordered and received the power connector. After doing some research on line I have not been able to find any Level-Temp switches that have any control output of more than 18 volts. I thought it might just be possible to find a way to get 24 volts to the thermostat to solve the power issue.  However I spoke with Google Nest customer support (non-technical support) who told me that installing the power connector will “bump(?)” the voltage up to 24 volts which is required to maintain charge on the thermostat’s internal battery. The thermostat is currently working fine (but with the voltage issue showing) and the internal battery is at an acceptable level but, according to the support agent, will apparently degrade over time without a c-wire or the power connector. 
My issue is that I have not been able to find any wiring diagrams, either in the basic installation manual or the pro installation manual, that show me how the power connector should be connected to the Level-temp control. 

Any help with this would be appreciated and can submit photos by email. 

[Derickf]

Hi @mkquesnel,

Thanks for reaching out to the community. I understand you've installed a new Nest Learning Thermostat (4th Gen) and are receiving a low-voltage error "N410" because your Level-Temp Control provides 18V. I appreciate you providing a detailed description of your setup. I'm happy to assist. 

Given your specific setup with the 240V baseboard heaters and the Level-Temp Control, this installation is more complex than a standard low-voltage system. To ensure the Nest Power Connector is wired correctly and safely, especially to resolve the “N410” voltage error, we recommend contacting a professional to help you with the installation.

I'll be waiting for your reply.

Best regards.

Derick.