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Tankless water heater gas pipe

user-7549075 | Posted in General Questions on


I am trying to install a tankless water heater to outside wall of house. I am planning to get a new separate natural gas line for the water heater. I wont be able to bury the pipe because the ground is concrete. Can I install the gas pipe around outside of house? I live in California.
Thank you

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  1. Expert Member
    BILL WICHERS | | #1

    That pic makes it look like you’ve already installed that gas line and are asking for help afterwards?

    Yes, you can run the gas line on the outside of the house. You’ll want to check if there are any local codes regarding physical barriers that might be needed to protect the pipe. DO NOT put the pipe underground anywhere (it sounds like you can’t do that anyway). Buried natural gas lines have a lot of issues and you’re better off using the yellow HDPE pipe and factory riser assemblies if you ever have to do that.

    You can generally use galvanized pipe in most areas now. That used to be a no-no, but has changed in MOST areas now. Check with your local gas company to be sure (they will know), and also check with your local building department. I have found times when the gas company says galvanized is ok but the building department doesn’t like it so you want to avoid any arguments.

    Regardless of whether you use galvanized or black iron pipe outside, I’d recommend painting it. The standard paint for gas lines is “battleship gray”, which rustoleum makes available in small (quart) cans. This is sold as a marine coating, and it’s not your usual paint. This stuff is tough. Prime the pipe first for a really nice job that will last. The paint will make the pipe look better, but it will also protect it from the weather.

    I’d recommend only using a good pipe dope too. You can use the yellow Teflon pipe joint tape made for gas lines, but I’ve always found pipe dope to work better. I like the “gimme the green stuff” pipe dope (silly name, but it works very well), but there are other good ones out there. Be sure to bubble test all your joints afterwards. I use a product called “mega bubble leak detector”, which works better than the old soapy water method.


  2. user-7549075 | | #2

    I just installed one pipe line in order to a take picture. I will follow your advice. Thank you very much Bill.

    1. Expert Member
      BILL WICHERS | | #3

      One other thing, be sure you size the pipe correctly from the tables, and be sure your gas meter (more the regulator than the meter, usually) can flow enough gas to run everything. Those tankless water heaters are big gas loads and gas appliances can have problems if the gas pressure drops too low.


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