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Radiant tweaking?

josephny
josephny Member Posts: 274
in THE MAIN WALL

Following up on my previous post....

IBC SFC-199 (with IBC's primary/secondary premade manifold)
Uponor EP radiant manifold
4 circuits, ~275' each
1/2" HePex in JoistTraks
JoistTraks 8" OC, attached to the underside (from inside the basement) of ply subfloor with hardwood flooring on top of it and mineral wool under it (between the floor joists)

With system calling for heat and Grundfos UPS15-58FC running on high, the flow rate gauges show a 0.4gpm rate. That is with the manifold valves completely open.

With boiler radiant water temp set for 125* F, the temp at the manifold input is 110* and at the manifold return is 100*

Is my flow rate high enough? Or, too high?

Other than a buffer tank (which is on my to do list), is there anything I should change/adjust/tweak?

Thanks!





Comments

  • Zman
    Zman Member Posts: 7,611
    Do you actually have 125 at the boiler? A 15-degree difference is a little unusual, I wonder if there is a piping issue. Is it piped primary /secondary?
    The .4 GPM and 10-degree delta sound pretty normal for those tubing lengths.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Rich_49
    Rich_49 Member Posts: 2,769
    Are you using the EP manifold stock thermometers to read the temps at the manifold ? If so , they are notoriously inaccurate , they'll show a Delta pretty well .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • josephny
    josephny Member Posts: 274
    Zman said:

    Do you actually have 125 at the boiler? A 15-degree difference is a little unusual, I wonder if there is a piping issue. Is it piped primary /secondary?
    The .4 GPM and 10-degree delta sound pretty normal for those tubing lengths.

    It is pipes P/S, using the IBC EZ-Pipe.

    I don't know if I actually have 125 coming out of the boiler.

    I wonder if there is an accurate clamp-on thermometer for 1-1/4" copper that I can get to measure temps?

    Using my extremely basic understanding, a 1.6gpm flow (0.4 * 4 circuits), with a 10 degree temp drop, results in 8000 BTU being radiated. I think I'd like a much higher radiation rate, no?

    Thanks!
  • josephny
    josephny Member Posts: 274
    Rich_49 said:

    Are you using the EP manifold stock thermometers to read the temps at the manifold ? If so , they are notoriously inaccurate , they'll show a Delta pretty well .

    Yes, I'm using the EP manifold stock thermometers. Maybe I should have plumbed in additional (and better quality) thermometers.

    Nonetheless, you think the delta is reliable and that figure (10*) is something I question as a good delta.

    Thanks!
  • GroundUp
    GroundUp Member Posts: 2,113
    edited September 2021
    275' loops with a 15-58 on high and 110* water should be producing nearly double that flow rate across 4 loops. Is it water or is it glycol? Something doesn't add up here. How many feet of Joist Trak are being used for your 1100ft of tubing?
  • Rich_49
    Rich_49 Member Posts: 2,769
    A 10* Delta T is widely accepted as the designed for Delta in a radiant floor . that being said , in newer more tightly built structures Deltas up to 20* work fine
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    josephny
  • Zman
    Zman Member Posts: 7,611
    Is 8,000 BTUs ~ 10 BTUs/Sqft? That sounds about right for 110 degree SWT.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • josephny
    josephny Member Posts: 274
    GroundUp said:

    275' loops with a 15-58 on high and 110* water should be producing nearly double that flow rate across 4 loops. Is it water or is it glycol? Something doesn't add up here. How many feet of Joist Trak are being used for your 1100ft of tubing?

    I'm using water.

    I don't know how much joist trak is being used, but I'd say just about all of the tubing is in track. I would estimate about 800'

    What could be going on?
  • josephny
    josephny Member Posts: 274
    Zman said:

    Is 8,000 BTUs ~ 10 BTUs/Sqft? That sounds about right for 110 degree SWT.

    8000btu for 900 sq-ft ~ 9 btu/sq-ft

    I thought I should expect to get ~20 btu/sq-ft
  • Zman
    Zman Member Posts: 7,611
    If you turn the temp up you will. 10 will probably work for most heating days.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • josephny
    josephny Member Posts: 274
    Zman said:

    If you turn the temp up you will. 10 will probably work for most heating days.

    Do you mean turn up the temperature of the boiler water? To what (130, 135, 140)?
  • josephny
    josephny Member Posts: 274
    Update:

    I raised the boiler radiant hot water set point to 135*

    The thermometers built into the EP manifolds read 120 in/110 out.

    I installed 2 Viega strap-on thermometers and they area 128/120. So, while temperature readings are different between the thermometers, the delta is closet.

    I just today lowered the setpoint to 130.

    Still not getting more than .5 or .6gpm in each of the 4 circuits -- tried pump on low/med/high.

    Am I wrong that a larger delta would be better?

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