Tie pex into water pipes at water heater? Hows this look?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Jeepnick, Feb 9, 2012.

  1. Jeepnick

    Jeepnick New Member

    Messages:
    18
    Location:
    Phoenix, AZ
    I need to run water to a bathroom addition I'm building. I'm using a 3/4" pex run with 1/2" branching off to fixtures. I need to tie into the water pipes and would like to do that at the water heater so as to bypass the rest of the house plumbing which has 1/2" hot water pipe. I'm not replacing the gas water heater at this time as it is still working fine.

    All pipe from the service entry to the water heater is in 3/4" copper. I plan to replace the water heater supply lines (they are old and nasty looking) and solder in some 3/4" tees at the same time and transition to my 3/4" pex lines which will then make the 50 foot journey to the new bathroom. Please see the attached diagram which shows how I plan to connect the pex to the system near the water heater.

    Is this OK, or should I plan to do something else. I'm set on pex, but not violating code is important, especially since this will all be inspected. I live in Phoenix, AZ. Thank you.

    WH Setup.jpg
  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,239
    Location:
    Land of Cheese
    Plastic piping should not be attached to a water heater. You want at least 18" of copper off the top the heater and then transition to PEX.

    UPC Code 604.11.2 Water Heater Connections. PEX tubing shall not be installed within the first eigthteen (18) inches (457 mm) of piping connected to a water heater
    Last edited by a moderator: Feb 11, 2012
  3. Jeepnick

    Jeepnick New Member

    Messages:
    18
    Location:
    Phoenix, AZ
    I suppose my diagram isn't that clear. The PEX transition will be near the ceiling which means there will be roughly 3 feet of copper between the pex and the water heater.

    Any other considerations? Thank you.
    Last edited by a moderator: Feb 9, 2012
  4. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    Is that true with electric water heaters also or is the 18" rule just for gas? If it applies to electric whats the reasoning behind it other than it's code? How far should a pex connection be away from the vent pipe of the water heater? You can install 18" of copper to the water heater but if thats vertical rise and the vent pipe is vertical rise they would still be close to each other......
  5. renstyle

    renstyle New Member

    Messages:
    13
    Location:
    Boone, Iowa
    From another layman's POV, it seems fine. 3/4" PEX should handle the 50' distance without much issue. The only real *concern* I would have had was also the WH-PEX clearance, which at 3' you've accounted for (and then some).

    I too have heard that while CVPC is not to be run directly to the hot side of a WH (and the cold if WH is gas), PEX can potentially run straight off the WH. Even if it was perfectly safe, I would never chance it if I didn't have to. I've accidentally touched my flue while the WH was running... WAY out of my personal comfort zone when using PEX.

    What you did with keeping the 3' lines is exactly what I would have done in your shoes.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,309
    Location:
    Cave Creek, Arizona
    The hottest water in the tank is at the top, and it applies to both hot and cold pipes. That heat will rise in the connecting pipes, but lose temperature to the air, which is why they want BOTH lines to have copper for 18" from the tank.

    UPC Code 604.11.2 Water Heater Connections. PEX tubing shall not be installed within the first eigthteen (18) inches (457 mm) of piping connected to a water heater
    Last edited by a moderator: Feb 11, 2012
  7. Jeepnick

    Jeepnick New Member

    Messages:
    18
    Location:
    Phoenix, AZ
    Thank you guys.
  8. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    Do what? So your saying the plumbing code wants 18" of copper because of heat loss??? You dont think copper losses heat? LOL
  9. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    Come on guys.....They want copper the first 18"of a gas water heater because that part of the vent gets the hottest,especially when the vent is cold and the heater fires...... After that you must still stay at least 6" away from the vent pipe.

    At least one pex manufacturer doesn't give two craps if you install pex directly to an electric water heater. Some codes do not allow it because their ignorant and the code is not perfect and thats one of a few reasons why its always changing.
    Last edited: Feb 10, 2012
  10. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Wrong hackney sorry to say i found this out the hard way !

    The 18" is to keep the plastic from melting from the hot water backing into the pipes this goes for gas or
    electric both by the time hot water rises 18" from the heater heat loss is enough to cool the water to below
    the melting point of plastic piping ie, cpvc, pex, sch. 40 piping etc.
  11. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Wrong Hackney sorry to say I found this out the hard way !

    The 18" is to keep the plastic from melting from the hot water backing into the pipes this goes for gas or
    electric both by the time hot water rises 18" from the heater heat loss is enough to cool the water to below
    the melting point of plastic piping ie, cpvc, pex, sch. 40 piping etc.

    THIS IS WHY IT IN THE U.P.C. CODE BOOK

    UPC Code 604.11.2 Water Heater Connections. PEX tubing shall not be installed within the first eigthteen (18) inches (457 mm) of piping connected to a water heater
    Last edited by a moderator: Feb 11, 2012
  12. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    You got so excited you posted it twice!!!

    I dont care what code book it's in thats non-sense. Post your source or a link.
  13. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    You seem to want to do things your way, regardless of the code. If you really think it's bunk, petition to have it changed. In the meantime, it behooves you to abide by the codes. When you got your license, you agreed to do this whether you thought it was good or not. You can always do it more robustly, as long as it is still code (code is the minimum standard), but that's between you and your customer and the building inspector, whether you have to satisfy one or not.
  14. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama

    I dont think you understand. No code book says that the hot water coming from a water heater will melt pex and if you keep it 18" away it will not melt. Thats CRAP. and its not in a code book. If it is....some guy in his moms basement wrote the book and named it code book.

    Google Zurn Pex installation guide and download the PDF. And read it.

    People can have their own opinion but they cant have their own set of facts

    Do I know more than most of the code book writers about plumbing? I KNOW I DO...I school inspectors and "plumbing authorities" on the regular.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    That close to a flue of a gas WH CAN damage pex or cpvc. Probably fine with an elecric WH, but I didn't think the codes differentiated type.
  16. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    . Codes may not allow it but that doesn't mean its wrong in practice. WTH in chicago they cant use pvc....what a freakin joke. Code will not allow it.

    Zurn expressly says that connecting pex to an electric water heater is perfectly acceptable.
  17. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,309
    Location:
    Cave Creek, Arizona
    quote; So your saying the plumbing code wants 18" of copper because of heat loss???

    Do you have a problem with comprehension? The copper is to protect the plastic from the hottest water at the top of the tank, NOT to "Cool" down the tank.

    UPC Code 604.11.2 Water Heater Connections. PEX tubing shall not be installed within the first eigthteen (18) inches (457 mm) of piping connected to a water heater
    Last edited by a moderator: Feb 11, 2012
  18. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    I dont think you comprehend that the tube is rated for continuous hot water use. How does the water cool off with a hot water recirculating system? Riddle me that? Do you really think 18" of copper is going to make any substantial difference in temp with the hot water circulating through the system?

    Goodluck explaining that one and making any sense.

    Infact Nibco only requires the tube be 12" away from a gas water heater........

    ZURN requires separation only for GAS water heaters. Zurn says its fine to connect their pex directly to electric water heaters. IS it your position that gas water heaters heat water hotter than electric? Please explain so I can comprehend that....

    NIBCO® PEX Fixture Connections
    • A metal adapter at least 12” long should be used to connect NIBCO® PEX tubing to a gas water heater. The tubing
    must be at least 6” from the exhaust vent.
    • NIBCO® PEX tubing can be connected directly to an electric water heater using metal insert adapters.
    • NIBCO® PEX tubing can be connected to PEX insert accessories as long as the barb meets ASTM F 1807 specifications.
    Such accessories include supply stop valves, ball valves, icemaker boxes, washing machine boxes, copper stub-outs and manifolds,
    Last edited: Feb 11, 2012
  19. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    Copied from Zurn.....I guess they dont comprehend well either......

    Zurn PEX may be connected directly to
    electric water heaters for residential
    plumbing applications. Zurn PEX has brass
    male and female threaded adapters and
    swivel adapters that can be used for this
    application.
    Zurn PEX must be kept at least 6" away
    from the exhaust vent of a gas-fired water
    heater. This is easily accomplished by
    using flexible water heater connectors.
    When the inlet and outlet connections are
    well away from the exhaust vent, such
    as most heaters with side connections,
    Zurn PEX may be connected directly to
    the water heater.
  20. Hackney plumbing

    Hackney plumbing Homeowner

    Messages:
    1,174
    Location:
    Alabama
    More from Viega......

    ViegaPEX Ultra tubing is
    manufactured to ASTM F876/F877
    standards and listed to ANSI/NSF
    Standards 14 and 61. It is chlorine
    resistance rated for both traditional
    and continuous recirculation PEX
    5006 (CL5) applications. ViegaPEX
    Ultra tubing is rated at 100 psi at
    180°F and 160 psi at 73°F.

    Temperature and Pressure Ratings:
    • 200°F at 80 psi
    • 180°F at 100 psi
    • 73.4°F at 160 psi

    PureFlow tubing should not
    be connected directly to gas-fired
    water heaters. The high temperatures
    of these appliances can damage
    the tubing.
    When connecting a PureFlow system
    to a gas-fired water heater, install a
    minimum of 18" of metallic piping
    beween the water heater and tubing,
    keeping tubing more than 6" away
    from the vent pipe. Where local
    code allows, PureFlow tubing may
    be connected directly to electric
    water heaters and used for hot water
    recirculation lines which do not come
    within 6" of the gas heater vent.

    ...................................................................................................................................................

    I hope everyone comprehends this info. You can have your opinions but not your own facts.
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