Need critique on residential plumbing layout

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Rossn, Apr 4, 2021.

  1. Rossn

    Rossn Member

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    Hi!

    I would really value a critique from a seasoned professional on my residential remodel plumbing layout. I would even be willing to pay for a detailed review and consult... just want to make sure I'm getting this right.

    Below is my best stab at the first (west) side layout for my re-plumb (replacing Kitek). I've tried to balance fixtures and line sizes, and reduce stagnation, manage temperatures, etc. There will be a few funny things due to radiant ceiling, etc and the remodel history of the home, that I won't go into now (just ask). I'm sure I have messed up a few things.

    This section shows 2.5 baths, kitchen, laundry. All plumbing is in the midfloor, with Red fixtures upstairs, Pink fixtures downstairs. Unless indicated otherwise, all plumbing is copper press, type L.

    Many, many, many thanks!
    Ross


    plumbing_west_plan_v1.0_large.jpg

    Edit: Adding the image in two parts, since the site downsizes the image
    plumbing_west_plan_v1.0_left.jpg
    plumbing_west_plan_v1.0_right.jpg
     
    Last edited: Apr 4, 2021
  2. James Henry

    James Henry In the Trades

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    It's fine.
     
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  4. James Henry

    James Henry In the Trades

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    Unless it's a very large house where the distance is great from bathroom to bathroom then 3/4" trunk lines are standard.
     
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  5. James Henry

    James Henry In the Trades

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  6. Rossn

    Rossn Member

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    Thanks, James - I can't tell you how much I appreciate your time and feedback!!! Very generous.

    The house, grown through remodels, is pretty long... from point of entry to the furthest fixture, 125' or so. 4,750sf/5BR/4.5 Ba. I am coming up with total around 40 fixture units (probably kicked up a bit higher having a rental space with w/d, kitchen sink, etc). That is around 34 cold/18 hot. Right around 1/2 those values east of the utility room (87' from furthest fixture).

    Do you think the 1" cold and 3/4" hot headed east from the utility room are appropriate for half of fixture units?

    Edit: I have been looking through that section of the 2015 IPC, and am running some numbers. I will study this more later today. I did confirm my meter is 3/4", and hopefully with the added bath I don't exceed my 1" supply line capacity.
     
  7. James Henry

    James Henry In the Trades

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    I suggest you sit down with a drawing of the complete floor plan and write on each fixture on the drawing how many WSFU's they are and the size of your meter and possibly the known pressure then go through SEC. 201 step by step and I think you will come up with most of your answers.
    SEC. 6 also has a few pieces of the puzzle.
     
    Last edited: Apr 5, 2021
  8. Rossn

    Rossn Member

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    Thank you. Laid out all the WSFU's in a table and was starting to look at E103, so thanks for re-steering me to E201. Definitely in-progress.

    My meter is maybe 225' from the street (hard to gauge, given it goes under a big ditch). For calculation, is it fair to consider the meter to the at the entry point of the home, using the pressure at the house... assuming I am not trying to size the supply line between meter and entry point to the house?
     
  9. James Henry

    James Henry In the Trades

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    I'm thinking booster pump, dunno.
     
  10. Rossn

    Rossn Member

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    I didn't type that right. Meter is maybe 225' from entry point into the house.
     
  11. wwhitney

    wwhitney Well-Known Member

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    Have only glanced at E201, but the "source of supply" referenced in it would be the water main in the street. So if it's 225' from the water main to your house, and then 125' from there to your farthest fixture, that's a maximum developed length of 350', for all the pipes that serve that fixture.

    I'm not clear how Table E201.1 was generated; since it lists different sizes for service pipe and distribution pipe, it would need to make some assumption about the relative length of the service pipe to the distribution pipe. If that assumption doesn't match your situation (service pipe is longer than any distribution pipes), then it may not be a good tool to use for your design.

    Can you tell more clearly the following: static pressure at some point at your house, along with the that point's elevation relative to the highest and lowest fixtures in the house; the exact length, size and material of your water service pipe from the water main to the point of entry in your house; and the meter size (location doesn't matter, be it at the street or at the house). [I've only skimmed the thread, so sorry if you've mentioned some of this, but it would useful to have all together in one place.]

    Cheers, Wayne
     
  12. Rossn

    Rossn Member

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    Hi Wayne, and thank you for your response. I got pulled into work last night, so didn't get to going through the E201 analysis, and likely won't be able to until tomorrow night.

    To answer your questions, and a little more info. I'm not sure how all the ups and downs affect pressure (I think in a closed system it doesn't matter, but this isn't a closed system).
    - in CAD, length from meter to house is probably closer to 275'. Over that 275' run, it gains an estimated 8' in elevation from ground level at the meter to entry point at the house. Frost line has lines buried about 3' below grade here, so I suppose it rises about 11' from the buried line). Note that along that path, id drops probably 3' under a 15' wide, 7' deep ditch.
    - At the house it enters about 3' below grade, which is the 8' above the meter pit (or 11' above the start of the buried line).
    - Once in the house, it rises 7.5' to the downstairs ceiling, runs about 25' (3/4 and 1/2" Cu) drops about 3' to a hose bib which measures 62psi static pressure. This is about 4.5' above the lowest fixture (toilet stop valve) and about 11' below the highest, furthest fixture (shower head). There is no PRV.
    - From the entry point at the house, the supply raises about 7.5' to the ceiling, and runs the 125' to the furthest fixture, however, at one point along the path, it will drop 8', run further then raise again... ultimately another 9' to the second floor. Raise another 7' to a shower head - the highest, furthest fixture from the entry point. The shower head should be 16' above the entry point of the water supply. That water supply entry point is either 8 or 11' above the meter (8' would be meter height).
    - Lowest fixture in the house would be a toilet stop valve at the same height as the water supply entry (however, the tubing goes from floor to ceiling, and back to floor level for this.

    The meter is a 3/4" meter. The water supply line is 1" roll copper... I would guess that is K. If original, I think the age would be around 50 years.

    I know this is all pretty complicated, and if you let me know if the ups and downs (ditch, and within the house) matter, I can also sketch it out with elevations.

    One additional piece of info I stumbled across in my notes last night... I have tested pressure with flow rate with the irrigation running, which taps into the supply line about 8' outside the house with a stop drain waste valve. With various zones running pressure dropped as indicated below:

    Static pressure for these tests: 68 psi (not sure if this was measured at a hose bib passing through the house, or one directly off the irrigation). Note: current static hose pressure is different - 62 psi at the hose bib passing through the house.
    8 GPM: 48 psi
    10 GPM: 40 psi
    12.5 GPM: 22 psi

    Those numbers aren't all that encouraging, eh?
     
    Last edited: Apr 6, 2021
  13. wwhitney

    wwhitney Well-Known Member

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    Elevation is just a linear pressure overlay on top of everything else going on, where 1 psi = 2.31 feet of water (which is just a way of expressing the density of water). So all that matters is the elevation of each outlet in your system, and noting the elevation at which your pressure measurements are taken. The individual ups and downs don't matter.

    On your pressure measurements under irrigation flow, you'd be most interested in pressure readings very close to where the irrigation and domestic system separate, is that what you have? If so, it seems like you shouldn't count on more than 10 GPM for domestic with your current water lateral, and had best schedule irrigation not to coincide with domestic use.

    If you accept 10 GPM as a maximum design domestic draw, one approach to using Table E201.1 would be to use the point at which you took the measurements as the start point for measuring developed length, and just to use the 40 psi table.

    Cheers, Wayne
     
  14. Rossn

    Rossn Member

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    Thanks, Wayne - I haven't gotten to digesting the approach yes, and this is very helpful. That makes sense... water head, is water head - so that simplifies things.

    I think that the difference from where I previously measured the pressure may be different enough (and long enough ago), that I should de-winterize the system and re-run the test (darn - we are just a few weeks away from freeze-free). At least, that will give the most meaningful starting point for pressure and pressure drop, and right outside the house, only about 1' above the entry point. I was getting flow rate from meter readings.

    Agreed I may not be able to count on more than GPM and need to run irrigation off-hours.

    Keep me honest here... I think I have a boiler valve for a drain on the irrigation manifold (actually between 2 manifolds, where I can attach a pressure gauge. If it looks like this:
    1" supply -> 1" irrigation manifold A -> drain valve -> 1" irrigation manifold B
    I should be able to measure the pressure at the drain valve, regardless of if my test runs from manifold A or B, right?
     
  15. wwhitney

    wwhitney Well-Known Member

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    I think in practice that it doesn't matter whether your flow test is discharging from manifold A or manifold B.

    I also think the complete answer is a bit more subtle than I understand. I do know that when measuring pressure during flow, the orientation of the measuring orifice relative to the flow affects the result, because of something called velocity pressure. I once attempted to calculate the magnitude of the effect and got that it was on the order of 1 psi for typical residential water flow/pressure tests, and so I could ignore it. But I'm not 100% confident in that calculation.

    If you have a hose bibb that is very close to where the water lateral enters the house, you can just do a domestic flow test with a pressure gauge on that hose bibb. Take the static pressure reading; then turn on multiple sinks one at a time. With three people, one at the meter to note the flow rate, one at the pressure gauge to read the pressures, and one running around to turn on fixtures, it would be very quick. There's no need to coordinate timing, as the flow rate at the meter should just jump up with each new fixture (maybe you need a minimum time between flow changes to observe the dial revolution rate) and the pressure readings should just jump down with each new fixture). You could do the whole thing as one person, but it would be alot of walking back and forth to the meter and a lot of wasted water.

    If you do an irrigation flow test, then it would be good to note the exact lengths and pipe sizes/materials from the branch point of domestic/irrigation to where you are measuring pressure. Then based on the flow rates, you can calculate the theoretical friction loss in those pipes, and deduce what the pressure readings would be at the domestic/irrigation branch point. [Same thing applies to the domestic flow test, except that I would expect the non-trunk piping involved in the flow path to be much less.]

    Cheers, Wayne
     
  16. Rossn

    Rossn Member

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    Ok, thanks for verifying. It sounds like for the most part I should be fine measuring it there, and I can try a secondary location but the reason to do it there is because the irrigation is literally tapped into the 1" supply line maybe 6' outside the house, and the furthest part of the furthest manifold is no more than another 5' - all through 1" tubing. I will try both ways.

    Even at that length, I am still scratching my head a bit at such pressure drop at 12 GPM. If one believes 2018 IPC Table E201.1 for 50-60 PSI or 60+ PSI, I should have 9.5 or 11.5 fixture units of flow... am I understanding correctly that I can then use Table E103.3(3) to say that I should be able to get 14-15.5 GPM? I'm not sure what pressure drop the table allows for, but my original numbers seem to indicate some problem (line or meter).

    Does anyone ever scope a 1" copper line? That would need to be a very small camera. I can recall seeing some minor dents in the supply line when I was re-working the irrigation, wondering the condition of it in the other 250'.

    Edit: those table numbers for flow were at 400', and the distance is probably closer to 275, which should even further raise the flow.
     
    Last edited: Apr 6, 2021
  17. wwhitney

    wwhitney Well-Known Member

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    Yeah, your earlier numbers do seem to be showing more pressure loss than the theoretical you should get from a 3/4" meter and a 275' of 1" type K copper. A random chart I found suggests that 10 gpm through a 3/4" meter should only drop 1.6 psi, and this calculator says 10 gpm through 275' of 0.995" ID pipe should only drop 8.5 psi. [The pipe material choice on the calculator selects a roughness coefficient and I believe copper is comparable to plastic.] But your numbers give a 28 psi drop, rather than a 10 psi drop.

    Do you know the pipe size, type, and length from the water main to the meter?

    Cheers, Wayne
     
  18. James Henry

    James Henry In the Trades

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    Up sizing a pipe gives it more volume to compensate for the smaller service pipe. As far as how the Table E201.1 was generated. One WSFU = 7.5 GPM., The number of fixture units that a specific plumbing fixture requires is not the actual amount of water that any one fixture will need at any one time, it is a number that incorporates the fixtures actual demand, the average time water will be flowing through the fixture and how often the fixture is used. The same is true for assigning DFU to fixtures. Knowing the average water supply pressure and flow capabilities of meters and pipes and friction loss and elevation loss, you are able to put it all together. Is it a completely perfect system? No. Is the water pressure always the same going to your house? No. It's average and the code is written to enforce the minimum standards and protect the public.
     
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  19. Rossn

    Rossn Member

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    Fair enough, and understood. 1 WSFU=7.5 GPM seems quite large - like most of a 3/4 copper.

    What I know about the meter is that it should have a 3/4" line feeding it, that would have been installed in the 70's. The main is on my side of the street, so I can't think that it is more than 10-14' horizontally, but they always to seem to be reasonably deep. I last had that meter pit open was maybe 2 years ago... when I run my test I will confirm, but seem to recall it was copper feeding it.

    I am wondering if the pipe is crushed somewhere. I have a yard hydrant that presumably ties directly into the supply line at about 110' from the meter. With no flow, other than the yard hydrant, would a pressure reading 160' away, at the house, be valid? I would think that without flow over the 160', the pressure reading should be representative, possibly accounting for some elevation change.
     
  20. wwhitney

    wwhitney Well-Known Member

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    With no flow, any pressure reading is going to be related to any other pressure reading precisely by elevation change.

    What would be interesting would be to take pressure readings at the mid-yard hydrant and at the house entrance simultaneously during various flow conditions. The pressure drop on the the lateral should be proportional to length. I.e. if static is 60, and under a given flow the house reading is 40 psi, and the midyard hyrant is halfway, it should be 50 psi.

    Under those assumptions if the midyard hydrant is 55 psi, that would suggest an obstruction between there and the house. And if the midyard hydrant is 45 psi, that would suggestion an obstruction between there and the meter. And if you happen to have balanced obstructions on both sides, you won't be able to detect it via comparative pressure drop.

    Cheers, Wayne
     
  21. Rossn

    Rossn Member

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    I only have one water pressure gauge, but the flow rate should be consistent with the irrigation, so I can just run two tests. It would be super useful to know if the issue is between the yard hydrant and house, as that would be the very expensive part to replace (i.e. has to be directionally drilled under the ditch). In any event, I will run some tests tomorrow evening, and know if we have an 8-10GPM flow limitation and the associated pressures.
     
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