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tapping into existing gas piping

sobriquet
sobriquet Member Posts: 46
Hello, I need to tap into an existing natural gas line to feed a garage heater I've currently installed. I'm looking for professional or informed opinions regarding best practices and what my local inspector will likely prefer. I'm running approx 20 ft 1/2" pipe, plus the equivalent length of fittings, I'm just under 40 ft, which is an acceptable length for the 57 CFH my heater requires. My question is how best to tap into my existing line. Looking at the attached photo, I can either remove the plug from the shut off valve currently installed and run an elbow and 3/4" pipe, reducing to 1/2" a few feet down the line. OR I can remove all the piping (feeding the water heater) back to the reducer tee and re-pipe with 3/4" pipe, replacing the 90 elbow (shown to the left in the photo) with a tee. Option 1 will be easier and more cost effectve, especially since I won't need to remove existing pipe. Option 2 would require more work and parts cost but would look a lot cleaner. Any thoughts would be helpful, thanks in advance - Dan.

Comments

  • JUGHNE
    JUGHNE Member Posts: 8,930
    IIWM I would use the existing tee. But shorten up the drop nipple, install a 90 and put the valve in the horizontal line. This might prevent it from becoming a head knocker. I always bump the water heater up to be running while I shut off the gas main at the meter so as to burn most of the gas out of the line.

    However have you calculated the pipe sizing for the whole system from the meter/regulator? There are at least 2 methods of pipe sizing involving the total/longest length of pipe and total load involved.
  • sobriquet
    sobriquet Member Posts: 46
    No I haven't calculated the entire system, although the pipe that feeds that water heater comes directly from meter, my boiler and range are on another main pipe. I will map it out and calculate it for good measure though.
    As far as shortening the drop nipple, is there any benefit in doing that besides height? If I can remove the plug from the valve and work from there, I won't have to shut the gas off until I make my final hookup
  • Ironman
    Ironman Member Posts: 6,554
    Without knowing all the particulars, it APPEARS that the line was sized large enough for an additional appliance, BUT you MUST do a load calc to confirm that.

    I'm not sure if it's still in the newer fuel gas codes, but it used to be illegal to tap out of the bottom of a horizontal line. Regardless, it's still a bad practice. I'd rotate that Tee so that the takeoff is from the side, not the bottom. Make sure you leak test everything with the gas cocks CLOSED at the appliances.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • JUGHNE
    JUGHNE Member Posts: 8,930
    I am familiar with the top or side tap and understand the logic for it. So if he put a tee with a drip leg under the horizontal pipe it would it qualify as a side tap? Most appliances are connected to the bottom of the horizontal main but have a tee with drip leg at the appliance.
  • sobriquet
    sobriquet Member Posts: 46
    Well I just made a rough sketch of my gas lines. Please know I am not a professional but am pretty good at understanding things given the right tools/info. All measurements were rounded up. Using the BTU/hr capacity charts I've found online, including equivalent lengths for fittings, I believe I can still pipe into the 3/4" line at the water heater without a problem. Take a look and tell me what you all think. If using the existing reducer tee may be questionable, I would remove it and install a regular 3/4" tee, changing the 1/2" piping to 3/4", and reducing to 1/2" closer to the water heater and planned garage heater. Note the garage heater will be just under 40 feet of pipe (including fittings) from the water heater branch.

    Also, I apologize, its a bit hard to see the yellow marks lines (3/4")
  • sobriquet
    sobriquet Member Posts: 46
    Attached photo
  • Ironman
    Ironman Member Posts: 6,554
    Where's the proposed line for the garage and its length?

    I think you. Need to check the but rating for the range...it seems low.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    Yes, 20k is not the typical range. One burner alone could almost draw that.
  • sobriquet
    sobriquet Member Posts: 46
    Opps you're right, that range is more like 50K BTU. I will modify my drawing to include the proposed garage line and post it soon.
  • sobriquet
    sobriquet Member Posts: 46
    Here is the updated proposed addition. Note the 20" length of 1/2" pipe feeding the water heater has been changed to 3/4". Also I changed the yellow 3/4" piping to purple for more clarity.
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    A gas range will typically be 10,000 BTU's for each top burner, 4 would be 40,000 then add the oven which can be around 25,000 BTU's that is a total 75,000 BTU's. You need to get hold of NFPA 54 National Fuel Gas Code to properly size additional gas piping.
    MikeZman
  • sobriquet
    sobriquet Member Posts: 46
    Looks like my range is 53K with 4 burners and the oven on. I just checked out the NFPA 54 book and it looks like my plan works, however the 2' section coming from the meter should be changed from 1" to 1 1/4" to be code compliant.
  • Ironman
    Ironman Member Posts: 6,554
    That's allowable because of connection size on the meter rack. No need to change it.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • sobriquet
    sobriquet Member Posts: 46
    Looking through NFPA 54, specifically chapter 6, I notice there is no mention of using equivalent pipe length for fittings when sizing pipe. Are these numbers estimated into the sizing tables?
  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Look in NFPA 54 version 2015 Annex B page number 54-126 and 54-127. Also in that section are procedures for different methods for sizing pipe systems.
  • Zman
    Zman Member Posts: 6,966
    The advise you are getting on pipe sizing is, of course, right on.

    One thing you might consider, the original installer was nice enough to leave you a tee to build off. You would be wise to leave a tee for the next expansion.

    You might check with the inspector to find out how he want's you to test this, you might need an isolation valve where you tie in.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • wogpa67
    wogpa67 Member Posts: 238
    Is the boiler a hot water boiler or a steam boiler?
  • wogpa67
    wogpa67 Member Posts: 238
    Is the unit you put a radiant tube or a unit heater?
  • JUGHNE
    JUGHNE Member Posts: 8,930
    Does NFPA 54 sizing ever consider the diversity of a load. Speaking mainly of the range. Pretty unlikely that all 4 burners plus oven would be on at once. (55 to 75,000 BTUH produced in the kitchen would probably keep the heating system off anyway).

    Just thinking of the Electrical Code that does not require full nameplate loads to be considered with multiple electric ranges connected to one service. That is probably mainly due to the rapid cycling of electric elements, but the unlikely event that all elements would be operating at once. And that multiple ranges be in use at once.
  • ChrisJ
    ChrisJ Member Posts: 11,967
    edited January 2016
    Electrical is protected so it's a different animal but as far as I know a stove needs a circuit that can drive the full load? Hardwired like a water heater needs to be derated by 20%
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 8,930
    The point I'm trying to make is that is a "demand factor" ever considered for a gas range? As I stated it is very unlikely that all burners in a range would be on high fire at one time. For this single family house I would certainly pipe full size when new.

    However for example, for adding on, if the range load was a make or break of upsizing say 1" to 1 1/4" for an initial short run then I would make a judgment call and say use 75% of the total range nameplate.

    Yes, every electric range circuit is protected as required. But for multiple ranges, (apartment bldg.) the actual service (equate to main gas pipe entering building) required to the building may be derated because of the demand factor of cooking equipment. [For example; 27 ranges @ 12KW each = 324 KW, however the total loading allowance used for the main service is only 42KW]

    Sorry, don't mean to hi-jack the thread.....just the point about that gas range load.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    We have to size for max load, the possibility that every burner is on at the same time.
  • sobriquet
    sobriquet Member Posts: 46
    Wogpa67, the boiler is steam and the garage heater is a unit heater, modine hot dawg hd60