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Outdoor Reset and Different Heat Loads

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newinnj
newinnj Member Posts: 37
I have a Navien NB-150 modcon boiler installed. The installer left it at the default outdoor reset of finned tube baseboard. My family who likes to wear t-shirt and sandals inside even when its 14 degrees outside was complaining the house was too hot. Reading all of the postings here I dropped the reset to low mass. The family is more comfortable now. I have three zones. The upstairs main living area is wood floors, the second zone office area is wood floor and third zone is the sub basement and is cement slab. Here are the temperature ranges for the outdoor reset on the supply side.
1. Finned Tube Baseboard Supply side 120-180 F
2. Fan Coil 140-180 F
3. Cast Iron 100-170F
4. Low mass 80-140 F Return Set 70-116F
5. High mass 80-120 F Return Set 70-101F
6. Radiators 120-170 F
7. Custom 104-180 F 86 -149F This can be user defined.
The dropping down to the low mass (wood floors) I think was the right thing to do. If it is the right thing to do then in the future when the basement does need to have heat (we are not using the space right now) what will be a temperature range that can satisfy all the different types of floors? I appreciate everyone's assistance.

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  • psb75
    psb75 Member Posts: 863
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    You need to mention what KIND of radiation you have. E.G. finned tube baseboard, radiant floors, panel radiators etc.
    ??
  • newinnj
    newinnj Member Posts: 37
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    Thanks and my apologies. It is radiant floors on all three zones pex tubing.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
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    When my mod-con was installed, they left the settings at default, which was way too hot. My W-M boiler allows me to use the defaults, or I can set the reset curves to anything I want. I have two zones, one radiant slab at grade, and one with baseboard. I replaced the two 3-foot long baseboards with two 14-foot long pieces to get the temperatures down while still getting enough heat; I now get more heat than when I had the 3-foot baseboards.

    Design temperature around here is 14F.

    For radiant slab zone, the reset curve goes from 80F supply to 130F supply when the outside temperature goes from 50F to 0F.
    For the baseboard zone, the reset curve goes from 120F to 150F supply when the outside temperature goes from 50F to 0F. The zone circulators are Taco 007 model, and the flow is a bit high for the baseboard zone: I get very little temperature drop (1F) between supply and return until it gets really cold outside.

    Of course, if you do not have the same boiler as I do, a house with similar heat loss to mine, and a similar outdoor environment to mine, your settings may be different.
  • hot_rod
    hot_rod Member Posts: 22,483
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    Is it a one temperature system with a mix of different heat emitters? Thermostats in each zoned area?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,546
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    That’s a mixed bag of emitters you have there.

    Question is how many that by design should use high temp could share a reduced low temp average water temperature.

    The only way to accomplish this is an emitter survey for each rooms heat loss. If the emitter can cover the load at a reduced water temp. Then see how many could accomplish with the lower water temp with each room, and it’s emitter. You might find a happy medium. If not you will have to cover the higher water temp emitters with the boiler, and mix down say the radiant.
  • DZoro
    DZoro Member Posts: 1,048
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    Still not sure what you have basement is concrete. Next two floors, staple up? thin set concrete? or?
    D
  • Gordy
    Gordy Member Posts: 9,546
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    Bottom line the low temp emitters would need their own mixing valve. Possibly two with the concrete, and the staple up running different temps. A taco I series with outdoor reset would be the answer. Then each mix temp would have its own reset curve.

    This is all conjecture with out doing the survey I mentioned.
  • newinnj
    newinnj Member Posts: 37
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    Thanks for the responses. I have some info. Three seperate thermostats on each floor for each of the zones. Top floor with wood flooring staple up. Middle floor with wood flooring and staple up. Basement with concrete slab. I am going to try the "happy medium" approach that Gordy mentioned. Eventually I have to get the emitter survey done. Also thanks for the other solutions!
  • Gordy
    Gordy Member Posts: 9,546
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    I guess I misinterpreted the initial post in that you had all those different style emitters in your home.

    I now reread, and see those are the water temp selections the navien offers for the reset curve.

    You can still try finding a happy medium with the staple up, and concrete. I’d watch the floor temp where wood floors are doesn’t get above 82 degrees.

    Unless the staple up is plated, and well insulated it might be tough to get a lower temp that works with the slab.