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Gas Pipe Sizing

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  1. #1
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    Red face Gas Pipe Sizing

    Hi there all

    I am new to posting but have been watching and absorbing for a number of years.

    Have a question. We are getting a gas log fire installed and the guy there said 1/2" copper pipe for the gas feed would be OK so I have got myself a 18m roll of said stuff.

    I want to run the pipe in from point A to point B ready for the Logfire installer to hopefully save on labour (I don't mind the grovelling under the house).

    To cut a long story short can anyone tell me if 1/2" pipe over a length of 15m will be OK for the logfire (which is rated at 32MJ/hr). It will connect to a 3/4 Galv Gas pipe main. Also on this branch feeds the Gas cooktop (up to 39MJ/hr).

    Again, I am not connecting just supplying the pipe and labour under the house. I probably should have got the plumber out first before purchasing the pipe. But anyway if anyone can tell me some gas pipe sizing info that would be good

    Steve

  2. #2
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    Did you get the right grade of pipe?

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  3. #3
    PLU.MBR.BL.DR. bricks's Avatar
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    I'd need to know the inlet pressure and the connection size of the heater.

    Doesn't sound like it's ok tho.
    If you dont play it, it's not an instrument!

  4. #4
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    Regulated pressure, mj ratings, length of run from meter. Correct grade pipe? I cant remember exactly, Ill have to look it up but 1/2" pipe has a limitation on how far it can be run its 3 or 5 metres, and probably wouldnt support the amount of gas a 'log fire' needs. A run of 15m may increase the index length of the installation and the MJ rating of a decorative log fire will significantly increase the MJ rating of the installation and may require the WHOLE installation be resized, not to mention the meter and regulator.
    Plumbers were around long before Jesus was a carpenter

  5. #5
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    The pipe I got was 0.91mm. The heater has a 1/2" (15mm) connection.

    The 3/4 Galv that would feed this comes off the bigger main (also galv) which looks like about 1.5".

    Originally there was an old Vulcan Wall Furnace running off the same distance 1/2" copper so I figured this new one would be OK.

    Anyway I have the plumber who is doing the actual connections coming tommorrow morning to have a look and talking to him on the phone he thinks 3/4 copper will be the go. Luckily I can swap the pipe and pay the difference.

    Maybe shouldn't just rely on what the Gas logfire guy says and actually talk to those in the know (ie this forum first - it is free)

  6. #6
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    You can do the last 6-8 metres in 1/2" for 32-38mj/hr guessing the rest of the details based on where you live. If you were in Sydney I might say to get a 2.75kpa regulator at the meter then you could do that run in 1/2".

  7. #7
    PLU.MBR.BL.DR. bricks's Avatar
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    Quote Originally Posted by zelig View Post
    You can do the last 6-8 metres in 1/2" for 32-38mj/hr guessing the rest of the details based on where you live. If you were in Sydney I might say to get a 2.75kpa regulator at the meter then you could do that run in 1/2".

    Just asking how you can confidently say that??
    If you dont play it, it's not an instrument!

  8. #8
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    Quote Originally Posted by zelig View Post
    You can do the last 6-8 metres in 1/2" for 32-38mj/hr guessing the rest of the details based on where you live. If you were in Sydney I might say to get a 2.75kpa regulator at the meter then you could do that run in 1/2".
    If your running on a low pressure system (1<7kPa) you may need a bigger meter with a bigger displacement to support the higher pressure and MJ rating. Regardless of being Sydney or Melbourne the same 5601 & AGL Gasfitting Rules apply.............
    Plumbers were around long before Jesus was a carpenter

  9. #9
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    Thanks for feedback all.
    My Plumber came on Saturday and he said 3/4 was the way to go so luckily I was able to return the 1/2" and upgrade.
    The Plumber seemed quite happy for me to grovel under the house and run the pipe in and he will do the connections. The price he gave me (seemed quite low to me) may have reflected this.

  10. #10
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    Glad you got it sorted mate, it is a bonus if someone is willing to crawl around on their guts under a house for you.
    Plumbers were around long before Jesus was a carpenter

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