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Thread: Gas Flex Lines

  1. #1
    Join Date
    Feb 2007
    Posts
    83

    Gas Flex Lines

    If a flex line is installed on a 180000 btu appliance and the flex is only rated for 150000btu Is it correct to say you can still run at the required gas pressure but the capacity in btus will be under fired?

    I condemed a bunch of unit heaters that hade under sized lines and was having a discussion with another tech and he said that the pressure would be lower but I dont agree you just wont be firing at the rated btu?

  2. #2
    Join Date
    Oct 2007
    Posts
    12
    What are these "unit heaters". I might be wrong about any or all of this below so someone correct me.

    Are you talking about when they hard pipe it to the unit and the last 2 or 3 feet going into the unit is flex? I believe this is not to code in a lot of places? most places?

    I think these flex connectors are intended for appliance, like as in ranges, water heaters etc.

    Would imagine they get away with this because inspectors don't know better or it isn't getting inspected. It's fast, cheap and they are lousy fitters. I see this all the time. Same in other place?

    Think you should put a manometer on a couple of them with all of them running. Maybe the largest one and the one with the longest pipe run, and this should tell you if you have enough flow.

    Had a boss who came down on me for doing a nice piping job once. I put a lot of effort into sizing the pipe, drip legs, unions, hard piped all the way to the valves. He told me It should have all been 3/4" and those flex connectors to the units. If we would have done that they would have been screwed by undersized pipe. I watched the pressure drop a little bit when I started all the units, undersized surely would have been low.

    What do you mean by condeming? This might be a little harsh

    Oh yeah just read your post again, yes it will be lower, it's called pressure drop, maybe not much or measurable but every inch of pipe even if it's the same size creates it

  3. #3
    Join Date
    May 2007
    Location
    San Francisco
    Posts
    258
    I overheard some folks at the parts house the other day saying that it will soon be illegal to use unions on natural gas pipe. they say you will have use a nipple with straight threads on one end, reverse threads on the other. this will be a pain in the ass, I say

  4. #4
    Join Date
    Feb 2007
    Location
    Las Vegas,NV
    Posts
    748
    I was surprised when I found this site, how many of the pros hard pipe right into a furnace. Everywhere I have lived, CA and NV, that I have seen, was always installed with a flex connector. I like the idea of not using a flex connector, but I can see where it might take some skill to hard pipe right into an appliance and have it turn out right. I am also surprised to see unions on many of the indoor furnace installs beacause where I lived in Cali, they were illeagle to use indoors. I always wondered if the flex connector issue might have something to do with earthquakes to allow a little appliance movement without breaking something loose, but I may be wrong.

  5. #5
    Join Date
    Feb 2007
    Posts
    83
    I agree there may be some pressure drop but at the same time you can still have the same pressure but not be able to deliver the same cubic feet of gas per hour. Pressure and volume are not the same. Like a garden hose weather it is 1 inch or 1/2 inch it will still deliver water at the same pressure just not as much an hour correct?

  6. #6
    Join Date
    Jul 2001
    Location
    VA
    Posts
    2,801
    Quote Originally Posted by jcarlding View Post
    I overheard some folks at the parts house the other day saying that it will soon be illegal to use unions on natural gas pipe. they say you will have use a nipple with straight threads on one end, reverse threads on the other. this will be a pain in the ass, I say
    UH huh, that'll happen.

    Then again you are in Ca, a whole different country.
    ___________________________________________


  7. #7
    Join Date
    Sep 2006
    Location
    The depths of hell in PHX AZ
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    Quote Originally Posted by AC-boy View Post
    Are you talking about when they hard pipe it to the unit and the last 2 or 3 feet going into the unit is flex? I believe this is not to code in a lot of places? most places?

    I think these flex connectors are intended for appliance, like as in ranges, water heaters etc.
    I thought this was illegal as well. Anyone know for sure? If not illegal it's not quality if you ask me. Those things have a place and permanent installation isn't one of them if you ask me.
    I will believe that the government is broke when the welfare checks start bouncing!!

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