Recirc system add a loop

Discussion in 'General Plumbing Help' started by hardwite, Mar 9, 2019.

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  1. Mar 14, 2019 #21

    breplum

    breplum

    breplum

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    It is truly idiotic (criminal, frankly) that your plumber used standard fittings for bends (instead of bend supports or large loops), and also that the pipe was not fully insulated!
    Proper installation standards for recirculation has always called for "long sweep" fittings with recirculation.
    Insulate the piping as a smart step. Pull those pipe supports, insulate with minimum 3/4" insulation...1" is great if you have economical access to such. Then restrap as per PEX spec of 32" (retired for two years, and hope I remembered correctly!)
    Low velocity is exactly what you want when running recirculation systems.
    You appear to have low velocity now, so be happy with that.
    High velocity causes erosion.
    We have run lots of giant loops successfully, like you described your house has and also, alternatively successfully used a simple site built manifold with circuit setters or plain lever handle ball valves to tweak the two or three loops.
    Add an good aquastat or snap on Grundfos aquastat.
    Multiple pushbutton or motion activated might be a really good option. Gothotwater, ACT D'mand systems are terriffic and deserve your consideration. They have a "thermosensor" built in.
    They offer wireless, but then there is the battery replacement task adnauseum.

    Get yourself a bright plumber who has experience.
     
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  2. Mar 14, 2019 #22

    hardwite

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    I could complain all day. I chose the wrong general contractor, and several systems in the house are just wrong or sub-standard. My problem now is how do I know whom to trust, other than do it myself.

    I had asked about insulation, but the up-charge was high and I planned to do it myself later. My contractor made it clear that his plumber does not do insulation (not sure why, and maybe not from the plumber, but either way, a signal to go elsewhere that I ignored). I am glad I passed on it though if I rework the system.

    I have learned a lot - wish I could have learned by researching on the net though!!
     
  3. Mar 14, 2019 #23

    hardwite

    hardwite

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    I estimate the downstairs loop will be ~209 feet with 16 T fittings.
    The upstairs loop will be 160 feet with 8 Ts and 6 90 degree elbows.

    All branches are probably 4 feet, rough estimate, and are 1/2 inch pex.

    The graphic does not accurately represent the number of appliances.

    The open decision point is how to realize the two loops. is it possible to balance the flow using valves, or do I need two pumps? etc. This is not represented in the loop estimates above - probably a minor impact.
     
  4. Mar 14, 2019 #24

    frodo

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    Is this the one-line for a 2-loop with one pump and a 3-way valve?

    • loop44.png

    • YES, this is a loop that can keep the water circ'n closer to your fixtures.

    • I reworked your loop, But with out knowing the actual piping lay out, i could be wrong

    • If you can, Draw up a simple floor plan with the existing pipe route, And we can put the

    • 3 way and balancing valves in a good spot,

    • i found a couple of very reasonable priced valves on e bay...
    FYI, A balance valve is nothing more that a ball valve, with ports for a http://www.dwyer-inst.com/Product/TestEquipment/Manometer/Portable/Series490W

    Ok...thats like $5000.00 Their is a ''pour boy'' way of balancing
    You use a bucket and a watch. time how long to it takes for 1 gallon
    and adjust [throttle] a regular ball valve,
     
    Last edited: Mar 14, 2019
  5. Mar 15, 2019 #25

    hardwite

    hardwite

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    This might be more in my price range.

    Is the site-built manifold made of pex and fittings? One idea is to route from tank to a manifold serving the following branches:
    • Loop#1 (3/4" pex)
    • Loop#2 (3/4")
    • Sink#_bathRoom#1 (1/2")
    • Shower_bathRoom#1 (1/2")

    This bathroom is directly in path of both loops, and this would save ~20 feet of pex.

    How much in flow resistance will a manifold and its fittings add?

    And in my one-line,
    • would I replace the 3-way valve with another manifold?
    • would the ball valves be on the two loop take-offs from the outbound manifold, or at the return manifold, or other location?
     
  6. Mar 15, 2019 #26

    Diehard

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    Up to this point, with your latest info on the 2 loops, I have looked at them running separately, as I thought was one scenario by way of a switch.
    Just based on the lengths and the stated ftgs (just looked at Tee runs, not branches and didn't include losses such as 3-way valve or balancing valve). They come out pretty darn close to the same. The approximate system curves almost overlap. And we are doing much better for flow rates now.. I'm showing about 3 gpm with the existing pump. Even when that drops a bit for some of those unaccounted for friction losses it looks real good.
    Now as far as those 2 loops operating together, which by the sounds of the balancing valve, is a desired mode of operation(?), I'll look at that tomorrow, but I'll need to know the location of the 3-way valve to do that. Just need the estimated distance from either end, which starts and ends at the water heater. The location is required since downstream of that valve the flow will be about twice as much as the 2 upstream flows. (Hopefully that is!) So together it shown slow the rate of flow down. Bed time!
    Oops! That purple text was suppose to read, DOWNSTAIRS" . Not that it makes much difference. CIRC DWG UPS 15-55 SFC CURVES-2.jpg
     
    Last edited: Mar 15, 2019
  7. Mar 15, 2019 #27

    frodo

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    I have been having a problem with your circ line pump ever since the first day I saw it
    Hot water going through the circulation pump is more "active", ... When you push water through pipes, the path of least resistance will get the greatest water flow. When you PULL the water through the pipes, you'll create suction ....

    loop44.png
     
  8. Mar 15, 2019 #28

    Diehard

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    How do you get different flows at different locations in a closed system?
     
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  9. Mar 15, 2019 #29

    frodo

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  10. Mar 15, 2019 #30

    Diehard

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  11. Mar 15, 2019 #31

    frodo

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    Last edited: Mar 15, 2019
  12. Mar 15, 2019 #32

    frodo

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    heat, water weight, head.

    2.jpg
     
  13. Mar 15, 2019 #33

    Diehard

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    Sorry but my statement was just in response to your comments on the pump, "When you push water through pipes, the path of least resistance will get the greatest water flow. When you PULL the water through the pipes, you'll create suction ...."
    I was just pointing out that when it's a closed loop the rate of flow is the same throughout the loop. In other words how could it be any different? There is no "greater water flow".
     
  14. Mar 15, 2019 #34

    frodo

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    qustion.gif
     
  15. Mar 15, 2019 #35

    frodo

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    their actually is, weight of water, the bottom piping water is heavy because of head pressure
    the top piping has less density due to the migration of air bubbles
     
  16. Mar 15, 2019 #36

    Diehard

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    When it's flowing 1 gpm at the bottom, what's the flow at the top?:rolleyes:
     
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  17. Mar 15, 2019 #37

    frodo

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    Does that 1 gpm change the head pressure?

    Is the water heaver with 10' of head pressure on it?

    does air migrate to the top, or does it stay on the bottom?

    does air effect the operation of a pump?

    roll dem eyes now bia-itch :rolleyes::rolleyes::rolleyes: [playing here, do not get all upset} :D
     
  18. Mar 15, 2019 #38

    Diehard

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    I think you're off on some tangent.???
    Flow is flow!
    Yes All those things are some way related to flow. But the bottom line is flow rate vs flow rate.
    Over and out good buddy.
     
  19. Mar 15, 2019 #39

    frodo

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    Flow is flow, I am not disputing that fact
    you are correct...water is flowing

    What we are discussing is the manor in which the water is moved [flow created]
    heaver water with out air is easier to push
    than lighter water with air is to pull

    turbulence of moving water causes the air to move to the top of any system, closed or open
    air causes impeller cavitation which effects the flow
     
  20. Mar 15, 2019 #40

    Mikey

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    With multiple loops, you have multiple closed systems, but they combine to form a single, larger, closed system. Reminiscent of Kirchoff's rules for electrical circuits ( I are a EE, not a plumber). In the two-loop system, for example, you might have 3 gpm coming out of the WH, dividing into 2gpm and 1gpm loops, but recombining again at the WH cold side to make up the 3gpm return.
     
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