Home Run Plumbing Design For New Home with far away bath

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by brianslink, Aug 14, 2011.

  1. brianslink

    brianslink New Member

    Messages:
    22
    Location:
    Oklahoma
    I have a new 2700 sq ft home that is framed and dried in. No plumbing or electrical has been installed yet. The master bath, laundry, kithcen and a 3/4 guest bath are all on one side of the home and all in close proximity to each other. Then on the other end of the house (65 feet away) is another full bathroom with a tub/shower combo, toilet and 2 lavatories. This is a kids bathroom (I have 3 girls) and I know this bathroom will be used extensively for the next 15 years.

    I have been able to design a Pex Home Run plumbing plan for the main part of the house. All of the plumbing fixtures (except that bathroom on the other end of the house) are within 28' of my hot water tank so I know a home run desigh will get hot water to all of those fixtures quickly. My issue is this far bathroom. I want hot water quickly at this location, but I don't want to circulate hot water to all of the fixtures and upset the home run design.

    I was reading about an on demand system called the Chillipepper. I like this concept for that far bathroom and I like the idea of pushing a button to call hot water to that location only. I dont want a recirculator on a timer nor do I want it on a thermostat. Is it possible to have this bathroom plumbed as a seperate zone with the ability to draw hot water to it quickly, but still use only a single hot water heater for the whole house? How can I accomplish this?
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Don't overthink this. You can recirculate to the far bathroom. It might also make sense to put in a separate water heater, possilby tankless, located at the far bathroom.
  3. brianslink

    brianslink New Member

    Messages:
    22
    Location:
    Oklahoma
    I really don't want the additional expense of a tankless. I want to recirculate the far bathroom only. Can this be done?
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,924
    Location:
    New England
    Certainly it can be done. You'd want to run a dedicated return line. Any recirculation system needs a checkvalve. There are all sorts of ways to turn a pump on - a simple adjustable time delay relay, pump, check valve and add a low-voltage control circuit would do it if you wanted to roll your own. Push the button, the relay activates for your adjusted time, then shuts off. WOn't come back on until you press the button again. Or, you can buy a packaged system which may be cheaper. If the pipes are insulated, running in conditioned space, and you have a system with a properly working thermostat, it really doesn't use much energy, though, even when running 24/7. The low-head pumps are typically in the range of 1/25HP, maybe 30W (and they often don't draw that much), then the control circuits which won't take much, either. Thermal losses aren't much if the pipes are insulated, either.
  5. brianslink

    brianslink New Member

    Messages:
    22
    Location:
    Oklahoma
    Jadnashua, Thanks for your input. Do you know of any diagrams showing exactly where to tie the return line in and where to put the check valve so that I don't recirculate the all of the hot pipes in the entire plumbing system...just the leg that travels to that far bathroom?
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,135
    Location:
    Maine
    I wouldn't do the home run thing. rather than that, run properly sized lines to each bathroom and install dedicated hot and cold manifolds close to the fixtures served. It cost's way less. It's easier to install and makes re-circ a snap
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    The circulation system will operate for ALL the faucets on the path from the heater to the connection to the circulation pipe. You connect the line to the pipes AT the faucet you want to have "instant hot" water to.
  8. jastori

    jastori New Member

    Messages:
    118
    Location:
    Illinois

    A recirculation loop will not affect your home-run lines that are not on the loop. In other words, leave your home-run lines as they are, and add a recirculating loop for the extra bathroom.

    Design a loop for the remaining bathroom with a properly sized supply and dedicated return line. This will be designed exactly as it would be if the other home-run lines did not exist. The check-valve goes in the dedicated return line, typically near the entrance back to the water heater.

    Grundfos has a .pdf document available on-line titled 'Hot Water Recirculation Guide' that has diagrams of several layouts (should be able to find by googling).
  9. brianslink

    brianslink New Member

    Messages:
    22
    Location:
    Oklahoma
    Diagram

    Jastori, Thanks for your advice. I have a diagram that is attached showing two scenarios for my design. They are identical except Design A uses "T" fitting to the manifolds and Design B has recirculation THROUGH the manifolds. I am unsure which is correct. Also, after looking at my diagrams I am open to suggestions for improving my design. Thank you for all your help so far. Image is below. If for some reason it does not show up then here is the link to my diagram: http://i1130.photobucket.com/albums/m523/rockytopsales/Plumbing/PexPlumbingDesign.jpg
    Pex Plumbing Design.JPG
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    For all practical purposes BOTH designs are exactly the same as far as performance is concerned. To do what you want to, you would connect the circulation line at the END of the "PEX to the fixtures" that goes to your shower valve. That would give you hot water to the bathroom, with some delay for most of the faucets, the way your drawings indicate, but also "instant" hot water at the tub/shower.
    Last edited: Aug 16, 2011
  11. jastori

    jastori New Member

    Messages:
    118
    Location:
    Illinois
    One thing to be a little careful about is the sizing of your supply lines. 3/4" PEX is not the same as 3/4" copper, due to a smaller internal diameter. You may want to verify that 3/4" PEX is OK for supplying a whole bathroom (including 2 lavs) 65 ft away. You also would want to be careful about ensuring that the size of the single hot feed from the water heater (which is supplying hot for the whole house) is adequate. The dedicated return line can be smaller (1/2" is probably fine), since this only needs to carry enough flow to maintain the temp of the loop.

    I am not a pro, and cannot give you specific answers on sizing these lines - maybe someone else can help.
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