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Condensing boilers and pumping article

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  • Paul48
    Paul48 Member Posts: 4,469
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    " fixed system delta with a flow rate that exceeds the primary --in equilibrium"

    How do you fix the system delta without varying the flow?
  • Gordy
    Gordy Member Posts: 9,546
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    btus
  • Paul48
    Paul48 Member Posts: 4,469
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    Forgive me if I'm wrong, but Eastman seems to be suggesting that this could happen with fixed speed pumps?
  • Gordy
    Gordy Member Posts: 9,546
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    It can, and it does, but not continuously in a bang bang setup. The movie not the snap shot.
  • bob_46
    bob_46 Member Posts: 813
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    hatt, maybe i'm missing something but with a 163.3 AWT how are you getting 40,000 out of the emitters if the design AWT is 170 ?

    There was an error rendering this rich post.

  • NYplumber
    NYplumber Member Posts: 503
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    Anyone ever think of adding a system sensor? The boiler will then raise the outlet temp to achieve the mixed system temperature and target the system temperature to odr while the boiler putlet temp moves higher then the plotted odr curve.
    :NYplumber:
  • bmwpowere36m3
    bmwpowere36m3 Member Posts: 512
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    Lochinvar uses a system sensor on their knight mod/cons
  • SWEI
    SWEI Member Posts: 7,356
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    As do most all the fully-featured mod/cons currently shipping.

    Note that using a strap-on thermistor (as the manuals often show) is not going to provide a good reading. Spend the extra $10 for a thermowell and please insulate the piping -- at least in & around the sensor location.
    Gordy
  • Gordy
    Gordy Member Posts: 9,546
    edited November 2015
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    SWEI said:

    As do most all the fully-featured mod/cons currently shipping.

    Note that using a strap-on thermistor (as the manuals often show) is not going to provide a good reading. Spend the extra $10 for a thermowell and please insulate the piping -- at least in & around the sensor location.


    I agree that response time, and accuracy can change a lot of the dynamics. Couple that with a set of delta t circ sensors of the strap on variety things can get quirky.
  • NYplumber
    NYplumber Member Posts: 503
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    Use heat grease inside the well too.
    :NYplumber:
    SWEI
  • hot_rod
    hot_rod Member Posts: 22,192
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    truth be know a sensor strapped tightly outside a copper tube, with insulation around it, will read as well as one in a well.

    If you use a well you must use some transfer grease or it may not read accurately.

    Most mod cons and all the Euro based solar controls use 6mm sensors, about 1/4" diameter

    Caleffi has an assortment of 6 mm wells.

    Thermistors are not very quick responders, it can take 10- 30 seconds for them to catch up with a temperature change. Wider the spread the longer it takes.

    I hung one outside recently and it took almost a minute to go from ambient room to outside temperature.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356
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    Hatterasguy said:

    SWEI said:

    Spend the extra $10 for a thermowell and please insulate the piping -- at least in & around the sensor location.

    Which thermowell are you using for that?
    Pasco 1449C (1/2" NPT male) and 1450W (3/4" sweat) both fit the 3/8" diameter thermistor probes used by most small boilers and residential controls.

    I have yet to find anything that short which will fit the 1/4" industrial probe size used in most commercial/industrial apps. The shortest thermowell we can get in that size is a solid machined stainless version with a 1" probe length (at ~3x the price.)
  • SWEI
    SWEI Member Posts: 7,356
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    hot rod said:

    truth be know a sensor strapped tightly outside a copper tube, with insulation around it, will read as well as one in a well.

    True with copper, as long as the bullet is properly oriented, clamped, and insulated.

    Those little 1450W's have a 3/4" insertion depth that fits in the bull of a 3/4" tee -- even on a 3/4" line. They're inexpensive and make for a very nice install.
  • Gordy
    Gordy Member Posts: 9,546
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    hot rod said:

    truth be know a sensor strapped tightly outside a copper tube, with insulation around it, will read as well as one in a well.

    If you use a well you must use some transfer grease or it may not read accurately.

    Most mod cons and all the Euro based solar controls use 6mm sensors, about 1/4" diameter

    Caleffi has an assortment of 6 mm wells.

    Thermistors are not very quick responders, it can take 10- 30 seconds for them to catch up with a temperature change. Wider the spread the longer it takes.

    I hung one outside recently and it took almost a minute to go from ambient room to outside temperature.

    With the indoor outdoor thermometer if you carefully take the plastic,encasement off the thermistor the response time is almost instantaneous. Fragile but very quick to respond. Never cared to try it with a metal encased thermistor.
  • NYplumber
    NYplumber Member Posts: 503
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    @Hatterasguy done add more complexity to your already accesorized project. Just place the system sensor at the outlet of the pump or after an elbow.
    :NYplumber:

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