Suddenly one zone controlled by Nest thermostat does not work until another zone thermostat is on

[leonidkr]

Have 2 Nest thermostats for 2 separate zones for heating (baseboard, boiler)
Setting temperature on one Nest 1 thermostat (controlling zone 1). Thermostat turns orange showing that it is working. But heat does not come up until I turn on another Nest 2 (controlling zone 2)
Only when I turn on Nest 2, radiators in the zone 1 start heating up.

I have had those 2 thermostat for a long time, but never experienced such problem - both Nest thermostats worked independently

[Jenelyn_O]

Hi leonidkr,

Thanks for reaching out. I'd like to confirm, in what country are you located? What type of Nest Thermostats do you have? Also, what is the make and model of your heating system? 

Best,

Jenelyn

[leonidkr]

Hi, I am in US, east cost, I have 2 nest learning thermostats and de-05-sv-wpc boiler by Peerless Boilers