Nest does not work with OpenTherm

[YannickU]

Hello,

I am experiencing problems with my Nest Thermostat incl Heatlink. I had a Nefit central heating boiler which supports OpenTherm protocol using a converter. But I never got that working. After a few years I got a new central heating boiler from ATAG (P27EC) which also supports OpenTherm but still no success.

I get the error H71 ( No OpenTherm connection) in both cases. So right now I am just dealing with on/off control but I find it very strange that OpenTherm does not work on two different brands of central heating boilers.

Technical details:

Thermostat

Model: Display-3.4

Serialnumber: 09AB01AC41180UP9

Software: 5.9.5-2

Heat Link

Model: Amber-2.5

Serialnumber: 10CA01AC401800QS

Software: 2.1.2-1

I hope someone can send me in the correct direction.

Greetings,

YannickU

[maedacortez]

Hi YannickU,

Thank you for reaching out. I understand that your Google Nest thermostat is displaying the H71 error code, and I'm happy to assist you. To better understand the situation before we proceed, I need to ask a few questions:

• What color is the light on your Heat Link?
• What is the distance between the Heat Link and the Nest thermostat? Are the Heat Link and display located on the same floor?
• What are the wires labels that you have connected?

I look forward to your response.

Regards,

Manuel