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2 Zone Natural Gas Boiler, One Zone stops working in Extreme Cold

As stated above, I am having an issue with my boiler in one of the zones when it is below Zero. I have an Ecobee on this Zone (Was replaced with this because of this issue). Usually overnight when the temp drops I will get an email from the Ecobee as follows:

You have an alert message from ecobee for thermostat: Main Floor (511852972871):
There may be a problem with the Boiler. For the past 4 hours the thermostat has been calling for heat, but the room temperature has decreased by 3.0F.

The Ecobee will also get a white message stating the same thing. When I hit ok and dismiss this message it seems to start to heat again and works until the next time it dips below Zero.

It also seems if I replace the Valve actuator with a new one, it will solve the issue for a time. This has been going on for a couple years. I get fed up hire someone they come out do as I mentioned above and then I end up buying a new Valve Actuator and worry about it next winter again.

I have had several techs out when this is an issue and have left the white notification on the screen, and once they dismiss this error it heats and they leave. I have had 3 different heat contractors there. Is there something I can do to troubleshoot this further before I call someone else and have them come, not fix it and charge me a couple hundred fro coming out and not fixing anything. I can add info on type of boiler etc if that helps.

Thanks to anyone that takes the time to read this and help out.


  • Jamie Hall
    Jamie Hall Member Posts: 23,536
    Is there anywhere that the piping for that zone goes in or very near an outside wall? You could, believe it or not, be getting some blockage from freezing in there, dropping the flow.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ProblemWithField
    Yes its pretty much all outside walls. It was supposed to be antifreeze, but to be honest I NEVER thought about that. I will do some investigating. Thanks so much for your reply! it is greatly appreciated!
  • GW
    GW Member Posts: 4,730
    Jamie my first thought too 
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
  • Zman
    Zman Member Posts: 7,588
    Some pictures would really help.
    Since we are guessing here, the zone that is heating properly may be stealing water flow from the other when it is cold and both zones are calling.
    How hot do the pipes feel? Try observing this under different conditions.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HomerJSmith
    HomerJSmith Member Posts: 2,477
    edited February 2021
    Are you saying that you have anti-freeze in your sys? Anti-freeze has a life span and should be checked on a yearly basis. If you do, what is the concentration and the coldest temp outside?

    Maybe the offending zone is on the side of the house that gets wind chill.