topic Re: Tekmar 256 not connecting with nest in Nest Thermostats

Tekmar 256 not connecting with nest

Milissacarter — Wed, 29 May 2024 19:06:51 GMT

I connected the nest thermostat wire to the Google power connector according to the wiring instructions red to red, white to white, and then the power connector to the tekmar256 common to common, red to red, white to thermostat. The nest has power and is on the wi-fi, however it isn’t triggering the furnace to turn on. Thoughts?

Re: Tekmar 256 not connecting with nest

Patrick_Caezza — Wed, 29 May 2024 23:50:21 GMT

@Milissacarter

Where are you located? In the USA/Canada or UK/Europe?

Boiler controllers can be a pain to connect to a Nest thermostat.

Do you have a picture of the original thermostat's wiring that you can post here?

Re: Tekmar 256 not connecting with nest

Milissacarter — Thu, 30 May 2024 00:32:35 GMT

I am located in the US. I am not looking to replace the Tekmar 256, rather connect the Nest to it. I don’t have a picture of the original wiring. I only changed two wires, moving them from the Tekmar to the power connector and then connecting the power connector to the tekmar. Is used the online manual of the tekmar and the power adapter and still doesn’t work.

Re: Tekmar 256 not connecting with nest

Patrick_Caezza — Thu, 30 May 2024 02:00:04 GMT

@Milissacarter

You might not need the Power Connector.

Terminal 7 - T to W

Terminal 8 - R+ to R

Terminal 9 - C- to C

Re: Tekmar 256 not connecting with nest

Milissacarter — Thu, 30 May 2024 12:36:38 GMT

Thank you. I did try that and it worked, however the boiler didn’t turn off when I turned the thermostat down. And the Nest complained that I need the power adapter.

Re: Tekmar 256 not connecting with nest

Patrick_Caezza — Sat, 01 Jun 2024 03:26:13 GMT

@Milissacarter

That makes sense. The boiler can't provide enough power for the thermostat.

Did you get an external 24-vac transformer too?

Re: Tekmar 256 not connecting with nest

Milissacarter — Mon, 03 Jun 2024 13:30:05 GMT

The google power converter is considered an external 24-vac transformer. When the power converter is connected the thermostat is powered, wifi connected, controlled at the device and wirelessly, however doesn't start the boiler when turned on.

Re: Tekmar 256 not connecting with nest

ovidioj — Wed, 12 Jun 2024 03:01:35 GMT

Hello @Milissacarter,

Thanks for posting in the community.
I understand how frustrating it must be to have your Nest thermostat seemingly working perfectly—powered on, connected to Wi-Fi, and controllable—but not starting the boiler. Let's see if we can figure out why it's not communicating with your boiler properly. I would like to know some information about your HVAC system.

Is this the first installation?
Do you get or see an error code on the display?
Do you have an idea or a picture of how the wires were installed?

Please keep me posted. Thank you.

Regards,

Jorge