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Dead ends and Legionnaires?

ChrisJChrisJ Member Posts: 10,677
Hi all,

We're currently doing a lot of repiping and have a few walls open.

While doing this I want to run a return for my domestic hot water from the second floor bathroom but it would just be a 10' long plugged 3/4" run of pex for a long time. Maybe forever.

It's just in case I ever get the time to do recirculating hot water and since it's in a wall now's the time to do it.

Is this asking for something really bad?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Comments

  • Jamie HallJamie Hall Member Posts: 12,367
    I wouldn't think so, @ChrisJ . Just when you do hook it up, flush it well!
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    ChrisJ
  • Larry WeingartenLarry Weingarten Member Posts: 1,720
    Hi, I'd see if there was a way to put a shut off valve at the beginning of the run to minimize the dead leg.

    Yours, Larry
    ChrisJZman
  • ChrisJChrisJ Member Posts: 10,677
    > @Larry Weingarten said:
    > Hi, I'd see if there was a way to put a shut off valve at the beginning of the run to minimize the dead leg.
    >
    > Yours, Larry

    Hi Larry,

    I thought about that but it's going to be in a drywalled ceiling so no dice. :(
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Larry WeingartenLarry Weingarten Member Posts: 1,720


    Hi, Can't use one of those beautiful hatches? o:)

    Yours, Larry
    Solid_Fuel_Man
  • ChrisJChrisJ Member Posts: 10,677
    > @Larry Weingarten said:
    > (Image)
    >
    >
    > Hi, Can't use one of those beautiful hatches? o:)
    >
    > Yours, Larry

    Are you married @Larry Weingarten ? :p

    Actually, we were considering doing a dropped ceiling for this reason as well as I want access to the tub drain etc.

    I don't like how they look but at the same time I don't like loosing all access to everything below the second floor bathroom.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    Zmanethicalpaul
  • ratioratio Member Posts: 2,280
    Not all lay-in ceiling tiles are ugly. Some look pretty good; I'm especially fond of the stamped tin ones. They are not, unfortunately, cheap. Another (expensive but) durable & unobtrusive tile is the drywall squares used in commercial kitchens.
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,927
    Just build yourself some type of hidden access. I built my own house and let me say there are a few "hidden access points" for cooler things than a valve!
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    ethicalpaul
  • ChrisJChrisJ Member Posts: 10,677
    > @Solid_Fuel_Man said:
    > Just build yourself some type of hidden access. I built my own house and let me say there are a few "hidden access points" for cooler things than a valve!

    Gladly.

    Any suggestions?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,927
    Will it be buried in a wall or floor?

    I assume wall, will it be close to your shower faucet? Can you put it under a false bottom shelf or cabinet?
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • ChrisJChrisJ Member Posts: 10,677
    > @Solid_Fuel_Man said:
    > Will it be buried in a wall or floor?
    >
    > I assume wall, will it be close to your shower faucet? Can you put it under a false bottom shelf or cabinet?

    Drywalled ceiling under the second floor bathroom. Second floor bathroom has tile floor.

    We gutted the first floor bathroom which is where the work is being done.

    The plugged end would be in the crawl space under the first floor bathroom.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • hot_rodhot_rod Member Posts: 12,939
    can you make a loop so it could be circulated?

    This German company builds a Venturi fitting to induce flow in loops that are not used daily

    https://www.kemper-olpe.de/fileadmin/contents/kemper/pdf/KHS_EN_02_13.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • ChrisJChrisJ Member Posts: 10,677
    hot_rod said:

    can you make a loop so it could be circulated?



    This German company builds a Venturi fitting to induce flow in loops that are not used daily



    https://www.kemper-olpe.de/fileadmin/contents/kemper/pdf/KHS_EN_02_13.pdf

    After mulling it over and looking at options, I may have come up with an idea which would make the dead end only a foot long or so.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNEJUGHNE Member Posts: 6,626
    Chris, do you have access to the bottom of your lav sink?
    I connected my recir line there and have a stop valve on it.
    Gravity recir to bottom of water heater tank only one floor down. Works great, instant hot water water in the shower with no pump involved.
    Search the wall for "Gravity recirculation". There is a Dec 2018 posting with many details.
    Solid_Fuel_Man
  • HomerJSmithHomerJSmith Member Posts: 844
    Gee. It's hard to say. 90 deg to 120 deg is an ideal breeding ground for the bacteria. Dead legs are of course in that range for the hot water line. I always try and avoid dead legs. As far as the circulation of hot water in a DHW line goes, new piping will be scrubbed to some extent with circulation. However, heated chlorinated water will break down the the piping barrier in all pipes allowing over time, places where bacteria could lodge. Water hardness and mineralization of the interior could, I would think, provide niches for bacteria to congregate, too.
  • ChrisJChrisJ Member Posts: 10,677
    > @HomerJSmith said:
    > Gee. It's hard to say. 90 deg to 120 deg is an ideal breeding ground for the bacteria. Dead legs are of course in that range for the hot water line. I always try and avoid dead legs. As far as the circulation of hot water in a DHW line goes, new piping will be scrubbed to some extent with circulation. However, heated chlorinated water will break down the the piping barrier in all pipes allowing over time, places where bacteria could lodge. Water hardness and mineralization of the interior could, I would think, provide niches for bacteria to congregate, too.

    New piping will be scrubbed But chlorinated water will break down the piping barrier? Huh?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • HomerJSmithHomerJSmith Member Posts: 844
    edited October 2019
    Chrisj, to clarify your huh?, what I meant was that new pipe is much smoother inside and therefore the bacteria has less to cling to and can be more easily washed away. Hot chlorinated water breaks down the barrier layer on the inside of the tube, allowing the bacteria something to cling to. The piping that most resists this breakdown is CPVC as I understand it.
    ChrisJ
  • ChrisJChrisJ Member Posts: 10,677
    > @HomerJSmith said:
    > Chrisj, to clarify your huh?, what I meant was that new pipe is much smoother inside and therefore the bacteria has less to cling to and can be more easily washed away. Hot chlorinated water breaks down the barrier layer on the inside of the tube, allowing the bacteria something to cling to. The piping that most resists this breakdown is CPVC as I understand it.

    Ah I see.
    That makes sense.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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