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Help with Nest Thermostat

I've had a Nest thermostat for over 2 years and it has worked fine up until I just recently got a new steam boiler. I previously had a Weil Mclain EG50 which was oversized and needed to be replaced so I just switched to a Weil Mclain eg35. Both of which operate off of 2 wires, on the EG50 I had the wires connected at the thermostat to the Rh and W1 terminals and it worked fine. I tried to hook up the new boiler the same way and am getting an error that seems to indicate too much voltage going to the thermostat. I tried an older "normal" thermostat and it seems to function with no issues. Any thoughts on what I may need to do to get the Nest functioning with the new boiler? The boiler came pre-wired and has the thermostat wires connected to the Y and G terminals of the transformer. Any assistance would be greatly appreciated.

Thanks

Comments

  • ChrisJ
    ChrisJ Member Posts: 11,978
    edited December 2015
    Only guess I have based on the short time I had the Nest is, flip the wires and see what happens.

    It won't hurt it, and may fix your problem. I've got a feeling it has no idea what it's talking about. My WM wires weren't labeled, just two black wires so I'm guessing the new one was connected randomly to your existing wires.

    Either that, or measure the voltage coming from the boiler but I doubt the new transformer is bad and feeling higher voltage than normal.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SlamDunk
    SlamDunk Member Posts: 1,110
    https://nest.com/support/article/When-Nest-needs-a-common-C-wire

    This may help. If not google "Nest is a power thief" or something like that.
  • erobinson85
    erobinson85 Member Posts: 19
    I tried flipping the wires around with no success. I have seen articles about adding the common C wire. I am planning to try that tonight and see if it works. I was hoping someone else has had a similar experience and could share how they solved the problem.
  • Mark N
    Mark N Member Posts: 1,090
    The error message was the voltage is high. Did you measure the voltage?
  • iix
    iix Member Posts: 18
    You can go into settings/technical info and it will list the voltage its seeing under Voc. Divide the number there by 1.414 and that will give you the voltage at the stat. Nest calls for 20-30 VAC
  • erobinson85
    erobinson85 Member Posts: 19
    edited December 2015
    Mark N said:

    The error message was the voltage is high. Did you measure the voltage?

    I checked the wires with a multimeter and was getting around 27 volts which doesn't seem to be out of the range. Still not sure why it is not working.

    I also tried connecting the common C wire as SlamDunk suggested and still no success.

    I am going to try purchasing the newer Nest 3.0 and see if that makes a difference. If that doesn't work then I guess I will have to forgo the Nest and move on to something else. What are some recommended thermostats with wi-fi for Steam Heat?
  • ChrisJ
    ChrisJ Member Posts: 11,978
    Honeywell Visionpro.

    http://www.supplyhouse.com/Honeywell-TH8320WF1029-Wi-Fi-VisionPRO-Thermostat

    Not as pretty as the Nest but more reliable and works just as good with steam.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    Bob Bona_4
  • Jamie Hall
    Jamie Hall Member Posts: 17,111
    ChrisJ said:

    Honeywell Visionpro.

    http://www.supplyhouse.com/Honeywell-TH8320WF1029-Wi-Fi-VisionPRO-Thermostat

    Not as pretty as the Nest but more reliable and works just as good with steam.

    Just as good? In my humble opinion -- a lot better.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Bob Bona_4
  • ChrisJ
    ChrisJ Member Posts: 11,978

    ChrisJ said:

    Honeywell Visionpro.

    http://www.supplyhouse.com/Honeywell-TH8320WF1029-Wi-Fi-VisionPRO-Thermostat

    Not as pretty as the Nest but more reliable and works just as good with steam.

    Just as good? In my humble opinion -- a lot better.
    I was trying not to insult anyone. :(
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Major7
    Major7 Member Posts: 44
    Did you get your problem resolved? I had a similar issue on an install, and I could share my experience.
  • erobinson85
    erobinson85 Member Posts: 19
    Major7 said:

    Did you get your problem resolved? I had a similar issue on an install, and I could share my experience.

    So unfortunately Nest was unable to resolve the issue and nothing that I tried seem to work. I had the Nest 2nd Generation thermostat and I decided on a whim to go out and purchase the 3rd generation to see if that would somehow fix the issue. Lo and behold, it now works fine with the 3rd generation (much to Nest's own amazement since they claim the differences between generations are marginal). I would love to hear what you're experience was and how you resolved it.

    Thanks
  • Major7
    Major7 Member Posts: 44
    I have an Ecobee3 with 3 remote sensors. Abs love it because I select which sensors are in the control loop for various use cases (home, sleep, away, etc.) Great for my three floor home where I have only the bedrooms controlled at night. I ended up having to install a relay in the boiler room because none of the original lines provided 24VAC, even when I ran the common line over an unused wire in the original bundle.

    To your situation, I think the 'working' condition on GEN3 is incidental to the install, and had nothing to do with the product. I think the Nest guys are right. The electrical differences between the generations are minuscule.

    Having said that, enjoy the nest. It's a great product. I know plenty of people who swear by them.