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Nest Thermostat - Always Wrong

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01grander
01grander Posts: 3
in A-C, Heat Pumps & Refrigeration

I hope this community is nicer than some others, I posted elsewhere and they were very condescending. I had a new hvac installed and I’ve had various issues but the issue I have now is that the nest thermostats are always horribly off, and they aren’t near a window, getting direct sunlight or have an air vent pointed at them.

I have two, so I just have to wonder if it’s the actual thermostats but these existed before my new system and the variance just didn’t seem to exist before. I’ll be downstairs and it’ll show 71 but my probe shows 74-75.

I went with a 2 stage Rheem, and it seems to be working but it’s worse than my old system and not sure if it’s just because of the thermostats but they worked ok on my last system.

Should I invest in nest sensors to supplement? Or switch over to Ecobee? I am also concerned that they are wired differently, one has the red wire in Rh and the other has Rc.


Any suggestions?

Comments

  • 109A_5
    109A_5 Posts: 4,508
    edited 7:57PM

    Home owners seem to love the NEST since they have convinced themselves they need the features, marketing genius. HVAC pros seem hate NESTs since they seem very problematic in various ways.

    In your case maybe the hole in the wall behind the thermostat where the wires come through is allowing a draft and skewing the temperature the thermostat detects.

    Additionally since they are a learning thermostat and you changed the HVAC equipment it may have to relearn or be reset so it can relearn the characteristics of the new HVAC equipment.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • pecmsg
    pecmsg Posts: 7,554

    good luck with your NEST!

  • ratio
    ratio Posts: 4,317

    What did you have before?

    There are a few environmental things that will cause a modern digital thermostat to read wrong, and some internal programming/design decisions that may result in some unexpected results, but by and large they are accurate.

    I'd check for a draft behind it like @109A_5 mentioned first of all.

  • 01grander
    01grander Posts: 3
    https://forum.heatinghelp.com/discussion/comment/1905339#Comment_1905339

    I did turn off the learning portion, I hate variability, just wanted control. I have dogs so I didn’t want them being uncomfortable. Is Ecobee any better with the hole affecting temp?

  • 01grander
    01grander Posts: 3

    I had these same nest thermostats, the hvac was a heat pump rheem but single stage, I was told 2 stage would be better overall but idk. Do I just put some insulation around the hole or some spray foam?

  • Jamie Hall
    Jamie Hall Posts: 27,820

    Got to admit that I don't love Nests — for a variety of reasons — but generally speaking inaccuracy isn't one of the reasons. With a two stage system — heat only? Or is it two stage heat and cool? You do have to be rather careful to get the wiring correct — but again, inaccuracy isn't a result of that, either.

    One major question to help us go a little further, perhaps. Do they maintain a reasonably steady temperature, even if it is not the correct one? Or do they let the temperature vary a good deal —more than a few degrees? Particularly if there is more variability than wanted, check the programming to make sure that all the program choices (there are a lot of them) correspond correctly to your actual new system

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • pecmsg
    pecmsg Posts: 7,554

    loose the NEST!

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