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Navien CC210 natural gas.

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Comments

  • gennady
    gennady Member Posts: 838
    radiant

    And what about radiant heat? Would customers hug 85F floor? average air temperature in the room with radiant heat will be 64-65F at 5' hight.
  • TonyS
    TonyS Member Posts: 849
    SWEI

    I use ODR on all my installs. Since most of my install are on existing systems it takes time to figure the set points and the slide. Baseboard fin drops dramatically at 120 so you have to make compensations unless you use an indoor reset. These compensations have to take into account that the indoor temp is not always going to be a perfect match with the outdoor temp. Personally I use an extra 5 degrees all the way through the slide. this provides ample heat recovery when they turn their stat back for a weekend away.

    But this comfort thing intrigues me. Gen and I install boilers in two identical houses ,we both use ODR but I add a stat as a high limit and he doesn't.

    So in some way he is selling comfort where people can go about their lives and think about other things and here I am just selling regular old heat.

    Anyway I just want him to show us a little math...to just share with us his way of setting this heat curve without any stats and the house stays the perfect setting all winter long.
  • SWEI
    SWEI Member Posts: 7,356
    existing systems

    With you 100% there - a proper room-by-room heat loss will get the boiler, pipe, and emitter sizing close enough that the system will balance.  Tuning the reset curve(s) can take awhile.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    edited October 2012
    Would customers hug 85F floor?

    It is worse than that in my house. I have radiant slab. Assuming it is cold enough (below the WWSD point), but 50F or more outside, if the thermostat calls for heat, 75F water goes into the slab, and I do not even notice any heat in the floor, though there must be some. Thermostat is 69F. I have an infra-red thermometer and I measure the floors sometimes. On very cold days, the floors can make it up to 80F and in my kitchen even a little higher. But not usually. That kitchen is ceramic tile. With my old non-reset system, it got too hot to walk on barefoot. Now it is sometimes warm enough to walk on barefoot, but never the "warm floors" some people expect from radiant floors. Design day around here is 14F, and with good windows and high status windows (mine are Marvin), it just does not take all that much heat to heat the place.



    The gas company charges me $48/month on the equal payment plan, for this 1150 square feet house. That includes running my indirect. They even skipped payments for two months early this fall because I had overpaid them at that rate.
  • gennady
    gennady Member Posts: 838
    radiant

    Radiant heat is not convection based but heat wave based. Your floor surface temperature must be 85F with no relationship to outdoor temperature. ODR for radiant is set up to keep this 85F temperature. You might need auxiliary heating for colder climates, to keep 65F of air at 5' level
  • TonyS
    TonyS Member Posts: 849
    What??

    So your saying you run all your radiant systems with a surface temp of 85 degrees..all the time? Or am I just misreading your statement?
  • gennady
    gennady Member Posts: 838
    edited October 2012
    85F

    Sure. 85F is the temperature of the surface of radiant floor all the time.

    we have hurricane sandy here, my fence fell already, and preparing to fly away, so I have plenty of time to spend at the computer
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