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how do I know how many btus a pipe will carry?

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Mitch_5
Mitch_5 Member Posts: 102
in THE MAIN WALL
the Golden Rules of Hydronic Heating has some good rules of thumb in the HW section page 64 on and for free not to knock day because you should have all his books as do I. But Burnham has a pocket book you can get from there distributors that has similar charts.

Mitch S.

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  • new guy
    new guy Member Posts: 2
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    How can I determine how many btus any given pipe size will carry at specific temperature drops?
  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
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    depends...

    on flow rate, pipe diameter and temp. drop end to end..detlta T...
    Generaly speaking..1/2 is 15K (1.5 gpm), 3/4 40K (4gpm), 1" 80K (8gpm), 1.25" 140k (14gpm)...20 temp drop...


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  • new guy
    new guy Member Posts: 2
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    right. and thank you.

    but where can I find a chart to calculate it as my DeltaT shifts?
  • Tim Doran_4
    Tim Doran_4 Member Posts: 138
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    System Syzer

    B&G has a System Syzer. You can go to thier web site and download it.

    Tim D.

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  • Edward A. (Ed) Carey_3
    Edward A. (Ed) Carey_3 Member Posts: 236
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    BTU cap of pipe

    This may help

    Ed Carey
  • Andrew Hagen_2
    Andrew Hagen_2 Member Posts: 236
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    dT

    It is important to remember that there is nothing magic about a 20 degree delta-T. It just makes the math easy.
  • hot_rod
    hot_rod Member Posts: 22,142
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    type of fluid and temperature also plays a part

    I use the Pipe Sizer program in Siggys HDS software. IT allows you to play what ifs with delta T glycol solution, temperatures, etc. With every input a chart appears showing the velocity in FPS so you can see where you have room to push some additional flows.

    1" copper can easily move 140 degree water, 180,000 BTU/hr at a 35 deltaT 10.8 gpm at 3.8 fps velocity 2psi pressure drop per 100 feet of tube.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • ptrim
    ptrim Member Posts: 1
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    Question?

    I have a 3/4" line about 100' from meter that I want to connect a 24" fire ring for fire pit and two 12" fire rings for fire bowls. Is 3/4" sufficient and how many BTU's can it support? 
  • Zman
    Zman Member Posts: 7,569
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    This thread....

    Is about hot water in a pipe. You question is about gas?

    I would suggest starting a new post. You will need a description of what the pipe sizes and lengths are as well as the btu sizes of all the appliances. The system gas pressure would also be needed.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    colinbarry
  • Gordy
    Gordy Member Posts: 9,546
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    Water verses gas

    Your post is referencing gas pipe sizing. This thread is in reference to btu carrying capacity of pipe filled with water, or glycol mix.



    Is this for lp, or ng?



    If ng 100' will supply 68000 btus about the average sized BBQ grill.



    If lp 100' will supply 162000 btus.



    BUT... What is the 3/4" line that is existing supplying gas to?



    If it supplying other appliances such as furnace, boiler water heater,BBQ,dryer etc. you have to account for that. Not as easy as tapping into that line for doing what ever you want.



    The bottom line is one of the appliances will starve for gas if it fires up, and the fire rings are in operation.
  • CMadatMe
    CMadatMe Member Posts: 3,086
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    Pipe Carries GPM

    The universal answer is, it depends. Pipe carries gallons per minute not a flat btu/hr. Btu/hr delivery utlizing a particular pipe size is predicated on the system delta-t.



    GPM = Btu/hr / (Delta-T x 500)



    As some have posted, there are maximum recommended gallons per minute for each pipe size.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Zman
    Zman Member Posts: 7,569
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    Gas

    He is trying to size a gas line.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Paul48
    Paul48 Member Posts: 4,469
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    Pipe Sizing Guidelines

    2-4 GPM=3/4"

    4-9 GPM= 1"

    8-14 GPM= 1 1/4"

    14-22 GPM= 1 1/2"
  • Paul48
    Paul48 Member Posts: 4,469
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    Trampled

    If you have a specific question, please start your own thread. That way someone elses question doesn't get lost in the shuffle.
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