Supply line sizing

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by nfc911, Oct 30, 2012.

  1. nfc911

    nfc911 New Member

    Messages:
    19
    Location:
    WV
    Doing a complete replumb of a house built in the 1840s or so. The water to the house is a well with 1" supply to a pressure tank. We installed pre-filters and water softner, and plan to install a 50-gallon propane water heater. The one side of the house has the laundry and a canning kitchen in the basement, a half bath and the main kitchen on the first floor, 2 full baths on the 2nd floor and a full bath on the 3rd floor. The is another full bath on the 2nd floor fed directly from the basement. I'm planning on using pex in trunk and branch configuration.

    For the cold side I was going to run 1" trunk from the water treatment from the basement to the 2nd floor. There would be a 3/4" tee off for the hot water heater, the separate 2nd floor bath, the laundry/canning kitchen and the 3rd floor bath. The other 2 full baths, half bath and kitchen would have 1/2" tees per fixture directly off the 1" trunk.

    The hot side would be more or less the same except it would be 3/4" trunk, with 3/4" branch to the laundry/canning kitchen, 1/2" branches to the separate 2nd floor bath and 3rd floor bath, and 1/2" tees for the remaining fixtures along the way.

    I had an inspector out for a walk through before I started work and he was concerned the 1" trunk wouldn't give proper pressure and also suggested a separate run to the 3rd floor so that it would be able to overcome the height without the other fixtures along the way. The fixtures in the 3rd floor bath would be approx. 35 ft above the pressure tank outlet.

    Other lengths that would impact this are the hot and cold trunks are approx. 120 ft, the distance to the 3rd past the 2nd floor baths is about 15 ft., and the separate 2nd floor bath is about 40 ft from where it would tee off the trunks.

    Looking for any real-life suggestions for doing it another better way. Looked at manifold configurations but was concerned about each hot water fixture having to wait for the water to get hot separately.

    Thanks for the input.

    supply-plumbing-10-30.jpg
  2. kreemoweet

    kreemoweet Member

    Messages:
    377
    Location:
    Seattle. WA
    How about some info on the flow capacity of your well/tank, and the actual set pressure? I can see where the 3rd floor fixtures would likely be
    starved under some circumstances, but actual usage scenarios are pretty much essential for accurate prediction. I would be very leery of any
    1/2 inch PEX in the circuit to any of the hi-volume fixtures such as shower/tub.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,230
    Location:
    Cave Creek, Arizona
    If opening the first and second floor faucets are going to affect the third floor's pressure, it will happen regardless of whether it has its own supply pipes, or not. In most cases, running 1" after the water heater connection would be overkill, but since you are using PEX or CPVC, that is almost the same as using 3/4" copper, and 3/4" PEX is like 1/2" copper, so your are not really "oversizing" the piping.
  4. nfc911

    nfc911 New Member

    Messages:
    19
    Location:
    WV
    How can I obtain the flow capacity? The well was put in about 8 years before we bought the property and we didn't receive any depth or flow information when the home changed hands. I believe the pressure is set to 30/50 (pump kicks on at 30 psi and off at 50 psi) or 40/60. There are only 4 of us in the household currently. The house is a historic home so we envision turning it into a B&B in the future (20 years). As far as the 1/2" lines in the circuit, do you mean the last legs should be 3/4"?
  5. nfc911

    nfc911 New Member

    Messages:
    19
    Location:
    WV
    Would running separate 3/4" lines to each fixture group or floor help with balancing the pressure? Isn't one of the advantages of the manifolds supposed to be balanced pressure that is unaffected by other fixtures being used? In the current layout would you suggest sizing the hot water line at 1" PEX then?
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,308
    Location:
    Maine
    go to Uponor's web site and look up modified manifold systems. You need to have a flow test done on your well too.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,230
    Location:
    Cave Creek, Arizona
    The well's capacity is ONLY a factor in refilling the storage tank, unless the usage is so extreme that it drains the tank and the pump is unable to maintain pressure. The benefit of a manifold system is that you have minimum connections and fittings in the walls and ceiling. Any "pressure balancing" due to the manifold is balanced out by the pressure drops of the longer runs from the manifold to the faucets. Since I am not a fan of any "copper tube size" plastic, because of their lower capacities, I do not use them., but if I did, I would use the next larger size plastic compared to what I use when I install copper tubing.
  8. nfc911

    nfc911 New Member

    Messages:
    19
    Location:
    WV
    Where on Uponor's site would I look that up? I typed it in their search and no results were returned. In some of their resources they mention Uponor logic plumbing but they don't go into details (at least not in the docs I've opened so far).

    Would this be a valid flow test:

    How to determine pump flow rate on systems with pressure tanks
    It is easy! All you need is a 1 or 5 gallon bucket and a watch or clock! It takes just a few minutes. Just follow these steps:
    1. Open any hose bib or faucet until pump turns on.
    2. Close hose bib or faucet and let pump fill up pressure tank until it turns off.
    3. Using a 1 or 5 gal. bucket, open faucet, collect and measure all water discharged until pump turns on.
    4. When pump turns on, immediately close faucet and start timing pump cycle.
    5. When pump turns off, record pump cycle time to refill pressure tank in seconds.
    6. Divide the number of gallons collected in Step 3 by the number of seconds in Step 5.
    7. Multiply the answer from Step 6 by 60.
    8. The answer in Step 7 is the average pumping capacity of the pump in gallons per minute (GPM).
  9. nfc911

    nfc911 New Member

    Messages:
    19
    Location:
    WV
    Haven't seen anything on this in a few days. Reached out to other sources on the web and another plumber and made a few changes. Split the floors on the high usage side of the house into 3 differnt groups and added recirculation loops to each group. Any thoughts?

    Thanks

    supply-plumbing-4-loop-11-08.jpg
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