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BTUs, WC, PSI, and pipe size

Bobbymac746
Bobbymac746 Member Posts: 6
Hello, I recently put up a new barn. When trenching, I ran 1” gas tite up to a riser at the meter as well as the barn. The distance is approximately 250’. I’m looking to buy an overhead garage heater and hire a plumber to install it all in one shot. I have a 30x48x16, so I was looking at 125,000BTU heaters, but now I’m not sure if I can provide enough BTUs.
Some of these charts say I will only get 88,000BTU while one says 1115k. If my gas meter says 5psi, do I use the bigger chart? I have no idea how to figure pressure drop. Thanks for any help.

https://www.gastite.com/downloads/pdfs/gastite_sizing_tables_natural_gas.pdf

Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,189
    edited January 2018
    I think you're too small my friend. Maybe upping the pressure, but you may still need the volume of a larger pipe.
    steve
  • Bobbymac746
    Bobbymac746 Member Posts: 6
    The 88,000 figure is off the .5psi chart. If my meter says 5psi, which that chart says I get over 10times that volume and would have an okay size pipe. Is that right, or am I wrong about what that means? Thanks.
    rick in Alaska
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,708
    Depends where you are located. On low pressure your only going to get 88,000 and maybe less that that as you have to allow for the interior piping to your heater.

    If you can run high pressure you can probably do it. It would require an additional regulator outside the barn.

    The reason I asked about the location is I am in MA. MA. does not allow CCST to be used on high pressure even though the mfg. says it's ok.

    You will have to check with your plumber and the local gas utility
  • Tim McElwain
    Tim McElwain Member Posts: 4,477
    How about a picture of the existing meter set up and rating plate on the meter?
    Bobbymac746
  • Bobbymac746
    Bobbymac746 Member Posts: 6



  • Bobbymac746
    Bobbymac746 Member Posts: 6
    I hope that’s the plate you’re looking at. As you can see 5psi. Doesn’t that mean, I get the high pressure unless I put a regulator on it (pre appliance)?
  • Zman
    Zman Member Posts: 6,792
    You pressure regulator will tell you what your pressure is ,not your meter. It does look like the meter is capable of 5 psi.
    Most residential services are set up for <0.5 psi. some are 2 psi but that is unusual.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ratio
    ratio Member Posts: 2,873
    MAOP means Maximum Allowable Operating Pressure, see https://www.elster-americanmeter.com/assets/products/products_elster_files/EAM-DS3535.pdf. A better indication of elevated pressure would be a regulator at the meter, since residential equipment runs at less than 14 in wc (≈½ psi). How 'bout a pic of the meter setting from a few paces back, showing from where it comes out of the ground to where it goes into the house?
  • Bobbymac746
    Bobbymac746 Member Posts: 6

    Here is a picture from a few feet back. Thank you all for the help. I keep seeing garage heaters for good prices on craigslist and I’d like to know it will work so I can hire someone to do this all in one shot versus having to hire someone to come tell me what I can use and then having to have them come back and hook it up.
  • ratio
    ratio Member Posts: 2,873
    It's looking like a low pressure service to me. You'll need to know the gas pressure & the minimum input pressure of the new appliance to see if it'll work. The table tells us that if your gas pressure at the inlet to the new line is under ½ lb & you flow 88k BTUh through a run that's 250' long you'll see about ½" pressure drop. It also says that if you increase that demand to 150k BTUh you'll see about 1½" pressure drop. If you're incoming pressure is high enough, say 9", and the nameplate says minimum 5.5" and a firing rate of 150k BTUh, then 9 take away the 1½ leaves 7½, more than the min of 5.5, so the math works. If your incoming pressure is 8" and the minimum is 7" you'll run into issues at 150k, but maybe not at 88k.
    Bobbymac746
  • Tim McElwain
    Tim McElwain Member Posts: 4,477
    There is no regulator so that meter is on a low pressure system operating probably at 6" W.C to 10 " W.C. pressure lees than 1/2 a pound. The meter can handle roughly 250,000 BTU's as a load.
    Bobbymac746Rich_49
  • Henry
    Henry Member Posts: 988
    This is not a DYI job! Where is the required sleeve for entering pipe that is going through the bricks, as required by code? I can imagine the number of other code and safety violations. There is a reason why code requires gas certification to work on an part of the gas system.
    Bobbymac746
  • ratio
    ratio Member Posts: 2,873
    There's a sleeve there. You can see the clearance along the top of the pipe.
    Bobbymac746Rich_49
  • Bobbymac746
    Bobbymac746 Member Posts: 6
    Already mentioned I wasn’t doing the job myself. Just want to buy the appropriate sized heater so I don’t have to hire someone twice ( to tell me what I can run and have to come back to install). Also no idea what safety violations you’re imagining, that is a photo of the house, there is a sleeve and it was all done by a licensed plumber when the house was built. Most of the folks here have been very helpful, not you though.