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Hot water baseboard heat - temperature fluctuations

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Hi there! I purchased a house a few months ago with hot water baseboard heat which is an entirely new concept to me - I've only ever lived in places with forced air heat.

I'm trying to figure out if what we are experiencing is normal. In particular at night, in our upstairs zone (we have two zones), we seem to experience rather large fluctuations in temperature. For example, I have the heat set to 66. I wake up sweating and see that the temperature in my room (which is also where the thermostat is) is 69. I go back to sleep. Then an hour or so later I wake up freezing and see that the temperature is now 64. I load on some blankets and go back to sleep, and then repeat this pattern all night. The thermostat is set to 66 the whole time. The fluctuations are the same in the other upstairs bedrooms.

I think my question is... Is that normal? Is that just how radiant heat works? Our boiler is old (20+ years), could that have something to do with it? Does anyone have recommendations to make the changes less severe? I already have a baby and insomnia walking me up all the time, I don't need weird temperature changes on top of it, haha.

Comments

  • bburd
    bburd Member Posts: 926
    edited November 2022
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    This sounds like a problem with the thermostat’s location or on/off differential (cycle rate). What type of thermostat controls the upstairs heat, and where is it located? Make and model? Can you post pictures of it, with the cover both on and off? Then we can better advise you.

    How is the temperature control in your other zone? Are the thermostats identical?

    Bburd
    STEVEusaPA
  • hmyerpost
    hmyerpost Member Posts: 5
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    We have a Google Nest Thermostat for both zones, and they are identical. Just the base model. I can definitely grab pictures in the morning and add them here if that would help! I installed them myself shortly after we moved in - but the very old Honeywell thermostats I removed did the same thing. We were hoping the switch would fix it but it didn't.

    We don't have a c wire though so I have an ac adapter plugged into the thermostats. I wonder if that could be messing something up.

    The downstairs definitely fluctuates as well but it seems less drastic? Though that might be because we are up and about so I just notice it less.
  • Jamie Hall
    Jamie Hall Member Posts: 23,567
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    aargh. The Nest rears its head again... Go into the Nest programming functions, and disable ALL the smart features. Every single one you can find. Room occupancy, setbacks, whatever. Then make sure -- also in the programming -- that it is set for hot water heat (they come from the factory set for hot air, which is completely different) and see if all that helps.

    It may not, if the old ones did the same thing -- assuming they had been set correctly, which they may not have been. If not, we can look further for problems.

    Let us know.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 9,850
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    Is the thermostat calling for heat when it is too warm? I'm thinking something happened that both zones are heating when either zone is calling(or it never worked right since you just bought it and you have no history of it working correctly).
  • hmyerpost
    hmyerpost Member Posts: 5
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    Hmm the nest doesn't seem to give me the option for hot water baseboard. It's currently set to radiator. Could that be the culprit? Maybe I just need a different thermostat.

    All the other features are off.

    I'm not sure if it is calling when it is too warm. It could be? It is hard for me to tell when it is actually running. It just tends to go back and forth between too warm and too cold and rarely is it the right temperature, haha.
  • pecmsg
    pecmsg Member Posts: 4,916
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    Do you still have the old t-stats?
  • mattmia2
    mattmia2 Member Posts: 9,850
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    I want you to see if the emitters are hot when there is no call from the thermostat in that zone but there is in the other zone to see if they both heat if either zone is calling. Turn the upstairs tstat way down or off and turn the downstairs tstat up. See if the baseboard upstairs get hot. See if the baseboard downstairs get hot.

    bburd
  • hmyerpost
    hmyerpost Member Posts: 5
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    I don't have the old thermostats unfortunately.

    I will try that experiment today and report back!
  • Big Ed_4
    Big Ed_4 Member Posts: 2,819
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    I would turn down the supply temperture to the radiant heat .There should be a mixing valve to adjust ..

    There was an error rendering this rich post.

  • Ironman
    Ironman Member Posts: 7,388
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    Big Ed_4 said:
    I would turn down the supply temperture to the radiant heat .There should be a mixing valve to adjust ..
    Ed, it’s baseboards. It would be extremely rare to have a mixing valve with them.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    STEVEusaPA
  • hot_rod
    hot_rod Member Posts: 22,396
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    Could be ghost flow on the overshoot side, but dropping below t stat seems more like a thermostat issue. Go buy a $20 basic heat only stat at the box store and see what it does.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bburd
    bburd Member Posts: 926
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    Where is that upstairs thermostat located? There is a common problem when they’re located in the hallway at the top of the stairs and are affected more by the temperature downstairs, which is usually set lower at night. Also the hallway is not near radiators in most homes, so there will be a lag in sensing an increase in temperature.

    A much better location for a second floor thermostat is in a bedroom, usually the master bedroom.

    Bburd
  • Big Ed_4
    Big Ed_4 Member Posts: 2,819
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    I think my question is... Is that normal? Is that just how radiant heat works? Our boiler is old (20+ years), could that have something to do with it? Does anyone have recommendations to make the changes less severe? I already have a baby and insomnia walking me up all the time, I don't need weird temperature changes on top of it, haha.

    He said he has radiant heat

    There was an error rendering this rich post.

  • Jamie Hall
    Jamie Hall Member Posts: 23,567
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    Big Ed_4 said:

    I think my question is... Is that normal? Is that just how radiant heat works? Our boiler is old (20+ years), could that have something to do with it? Does anyone have recommendations to make the changes less severe? I already have a baby and insomnia walking me up all the time, I don't need weird temperature changes on top of it, haha.

    He said he has radiant heat

    I don't think, from other comments, that he means radiant heat as we think of it. I think he means radiators or baseboards.

    But in answer to the original question there, no it isn't normal or anything close to normal -- but it is a control/thermostat question and has nothing to do with the boiler. It may be a poor thermostat location, it may be the wrong thermostat for the application, it may be a niswired control in the basement...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hmyerpost
    hmyerpost Member Posts: 5
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    Oh yes, my apologies - it's hydronic baseboard heat.

    Maybe I should just have someone come and look at it, haha.