Flare fitting in place of standard threaded?

Discussion in 'General Plumbing Help' started by djones, Nov 12, 2012.

  1. Nov 12, 2012 #1

    djones

    djones

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    My DIY plumbing has been strictly PVC except for adding a valve and hookup for an outdoor natural gas grill. I have a plastic flex furnace supply line that whistles so loudly you can hear it outside, it's a real pain in the ear. I think it's because it has a sharp bend in it right where it connects to the supply, but has to with the current plumbing - the supply is pointing straight into the a/c drain line.

    Long story short, I want to put an elbow in so the flex line can connect vertically to the supply instead of awkwardly between other parts of the HVAC and am hoping the whistling will go away. Without redoing a lot of the plumbing, I still have limited space, so I want to go from the brass valve to the flex line with one connection. All I could find was a 1/2 flare to 3/8 flare 90º. Can I use that flare fitting without any issues? I'm assuming I'll need to dope/tape the 1/2 side, but I thought I'd ask about potential problems since the flare on that side is just going to be sticking dumbly into the threaded pipe.

    Alternatively if I'm off base on the whistling and there's a better solution, I'm all ears.
     
  2. Nov 12, 2012 #2

    AQualityPlumber

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    Just a quick note, do not use thread tape on gas fittings. It can clog up the orphasus inside. Just cake on the dope on the threads and test for leaks when you are done.
     
  3. Nov 12, 2012 #3

    AQualityPlumber

    AQualityPlumber

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    And am I reading this right that you used pvc for gas piping?
     
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  4. Nov 12, 2012 #4

    djones

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    Ok, thanks. Not even the yellow tape on the back of the threads? What's it made for then?


    LOL no, sorry if that was confusing. I mean that my experience is mainly with PVC and *water*. :)
     
  5. Nov 12, 2012 #5

    AQualityPlumber

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    Again, do not use any thread tape for gas fittings. I'm sure they make tape rated for gas, but it's not a good idea. You will almost always get a pin hole leak and risk clogging up the unit if a piece Flys off inside. Use either a soft set thread sealent rated for gas, or a non soft set rated for gas. Make sure on the can it says it's rated for gas and fuel.
     
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  6. Nov 12, 2012 #6

    djones

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    Perfect explanation, thank you.
     
  7. Nov 13, 2012 #7

    IFIXH20

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    If the Furnace has a whistling sound when its running, it may be too much gas pressure , bad gas valve, flue issue ,cracked heat exchanger, burners need adjusted. I do not think Furnace repairs should be done my DIYERS due to the danger that can occur if the system is not running proper, thats just my opinion. ( HOPE YOU HAVE A CARBON MONOXIDE DETECTOR).
     
  8. Nov 13, 2012 #8

    IFIXH20

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    Do not dope the first three threads on gas
     
  9. Nov 13, 2012 #9

    djones

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    We do have CO detectors, and my nose is more sensitive than most to the additive. I've twice had gas company reps look at me like I'm looney when I say there's a leak and tell them which joint, until their detector starts beeping.

    I appreciate the other points though - I truly don't know why it's whistling, and was relying on my ear for the source. So it sounds like even if I've identified the location of the whistle, that may not be locating the reason?
     
  10. Nov 13, 2012 #10

    IFIXH20

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    Is the whistling constantly or when the furnace runs
     
  11. Nov 13, 2012 #11

    djones

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    Only when the furnace runs. No whistling in the blower, for instance when the a/c or the heat pump is operating.
     
  12. Nov 13, 2012 #12

    djones

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    And a pic of the connection if it helps. So to clarify, I'm wanting to use the 90º connector at the steel T where the reducer/flare is currently, not the brass valve.

    IMG_0795.jpg
     
  13. Nov 13, 2012 #13

    stevemachine

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    Like when the burners light?
     
  14. Nov 13, 2012 #14

    IFIXH20

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    I think the problem is related to one of the issues I mention in my earlier post. Have a licensed HVAC contractor check your system. I do not think the gas line is your problem.
     
    Last edited: Nov 13, 2012
  15. Nov 13, 2012 #15

    djones

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    Correct, whistling is only when the natural gas valve opens up, kicks in, and the burners light. When nothing is flowing through the plastic flex, there's no whistle. Placing your ear on the flex, you can follow it to the noisiest spot, the curve coming around directly from the supply.
     
  16. Nov 13, 2012 #16

    stevemachine

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    Yeah I agree, call in a pro. I really doubt the gas flex is causing the whistling. It could be a million other things. It's hard to diagnose online and definitely like ifixh20 said considering the risks of working on furnace without being fully trained is huge. It's not worth it in my opinion.
     
  17. Nov 13, 2012 #17

    djones

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    Got it, thanks both for the advice. I'll post back after it's diagnosed.
     
  18. Nov 13, 2012 #18

    stevemachine

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    Sounds good, its always nice to hear the end result.
     
  19. Nov 22, 2012 #19

    djones

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    Furnace technician was baffled and was hesitant to take a gas pressure reading, not sure why, but eventually did and found 8.8 inH₂O at the intake valve and said it's supposed to only have 7 inH₂O. Gas company is coming out next week to check.
     
  20. Nov 23, 2012 #20

    stevemachine

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    Yeah that's a little high, could be the problem but hard to say. Keep us updated!
     

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