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Thread: Codes for gas furnace in shop/garage...

  1. Default Codes for gas furnace in shop/garage...

    {I am hoping this is the right forum for this type of question, didn't look like it belonged in the existing home/repair section}

    Can anyone point me to a place that spells out the codes for a furnace in a shop/garage? I installed one years ago in my old house and per the advice of the local inspector, the furnace (or is it just the burn chamber?) has to be 18" min off the floor and on a pedestal that could withstand a good bump from a car. That and it had to meet the venting size requirements.

    I plan on doing this again this time (NG instead of propane this time), and having a licensed pipefitter hook up the gas line. And my local town inspector will inspect it afterward. I just don't want to have to re-do anything.

    One other question. I have a 2" electrical conduit running between the house basement and shop, probably about 22' total. The pipefitter says he thinks he can use it and an armored 3/4" flex line that we can pull through it. In the basement, he will tap into the house NG service.

    My question is in the garage, what is the best way plumb from the conduit exit to the gas valve? The conduit comes up virtually underneath the furnace. Can the flex line be used all the way to the gas valve? Or would it be best to run steel pipe down the side near the floor, and then couple to the flex line. What are the protection issues with this type of setup?

    In my old house the plumber used 1/2 flexible copper line along the back wall of the garage. Didn't seem like the inspector was too concerned about that.

    TIA

    JH

  2. #2

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    That old 18" raised requirement still applies any time you're putting a gas appliance in a building with cars or other stored gasoline. You really don't have to make a super heavy pedestal if you can core drill the floor and put in some cement filled pipes at all four corners. Anytime, in a commercial environment, where an appliance of any type can be bumped by cars, forklifts and stock pickers it's generally always a requirement that it be protected in some manner. Sometimes this means constructing a wall, fence, or adding pipes in the floor.

    There's nothing really in the fuel gas code (for commercial) that is much different at all than what's in chapter 24 of the IRC (for residential). These codes go on and on about pipe sizing and venting requirements, with very little about the actual fuel gas piping. It seems that you're particularly worried about protecting the CSST (flex) where it emerges from the ground. The only requirement is that the conduit sleeve extend at least 2" above floor level. These codes make almost no distinction between black iron pipe, copper, and CSST with respect to their ability to protect against physical damage. Common sense should prevail, however, and would cause one to arrange the pipe work in such a way that it's likelihood of being damaged is reduced. The flex can run the whole way to the gas valve (with a shutoff installed). In fact, it's generally a good idea that the final connection to any equipment that vibrates be flexible. There is also a requirement that the space between the flex and the conduit be sealed. There is commercially available compound to accomplish this, but the trade name of it escapes me at the moment.

    I can't really pin down a good online reading resource for you. You see, there's the "2003 International Fuel Gas Code" (from which the IRC takes it's gas section) and the "2002 National Fuel Gas Code". Neither one is very different than the other. Both must be purchased, so there's little text from either online. When it comes to commercial work, there's little self help information out there, since engineers want to keep all that information close to the vest. We try to help here as best as we can.
    "Nothing is foolproof to a sufficiently talented fool"

  3. #3

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    I just ran across this thread while searching for an answer to a shop heater question. I was amazed to read that it is OK to run a natural gas pipe in an "electical conduit". "I have a 2" electrical conduit running between the house basement and shop, probably about 22' total. The pipefitter says he thinks he can use it and an armored 3/4" flex line that we can pull through it. In the basement, he will tap into the house NG service." - I'm assuming there are live electrical conductors in that "electrical conduit". Does this truely meet NEC, or am I mis-reading something? Is this only true because it's "armored flex" or CSST?

    TIA for a clarification.

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