How are my gas appliances working?

busydadof3

I am considering adding an outdoor gas fire pit so I've started to read up on what it would take to make this happen. I have many gas consuming appliances in my home so I was hoping my supply would be adequate. Heading into the basement I was surprised to see a 3/4" gas pipe entering from the service. The typical sizing chart I've seen online tells me that there's no way this should work:

Service---- 20'-----Gas Range -------10'-----Gas insert-----15'-----2xFurnaces------8'----Dryer---5'----2xHWTs

Range: 8k BTU
Fireplace: 37K BTU
Furnace 1: 66K BTU
Furnace 2: 66K BTU
Dryer: 20K BTU
HWT1: 40K BTU
HWT2: 40K BTU


Total: 277K BTU

I have a '400K BTU' meter. The home was built in 2008 by a reputable builder so I'm assuming I am missing something here as the chart I'm finding online tells me that 3/4" supply couldn't keep half of these devices working at these runs. We bought the home in 2012 so we've been happily using (a lot of) gas since then and I'm certain I've had all of these gas consumers firing at the same time.

That said, how can I find out the true capacity of that gas pipe run? If it is possible to split off to a firepit, the T would go between the furnaces and the dryer. If not, what are my options? Replacing the 3/4" trunk with something larger would be a pretty big ordeal. My gas supplier said an upgrade to a 600K meter is easy and cheap (~ $100) ... if I were to do this, could I run another 3/4" in parallel to the current one, and allow that to feed the fire pit? I would like to add an outdoor kitchen at some point so would need that extra capacity down the road.

Thanks for any answers - really scratching my head over here.

busydadof3

I wanted to add, I am a total layman and any gas work would be done by a licensed plumber. I'm hoping to understand what can be done before I start down the rabbit hole on this project.

Steamhead

I bet the pressure in the line coming into the house is considerably higher than the inside gas lines. Take a pic of the meter including the piping around the meter and we can tell you for sure.

busydadof3

Thanks for any insight!

JUGHNE

Do you have a regulator at each appliance? As Steamhead said you might have pounds of gas pressure in your house, rather than ounces.

busydadof3

I'm not sure - I don't see anything out of the ordinary going to my furnaces/HWTs ... how would I knowo if there was a regulator at each appliance?

JUGHNE

The appliance regulator would be a smaller version of the device to the left of your gas meter. Maybe 3" or so in diameter. Should be installed between the small gas shut off and the valve of the appliance.

busydadof3

Is this little collar headed to one of the HWTs a regulator?

busydadof3

I see another headed to the furnaces:

JUGHNE

Under the red flipper lever shut off is a black pipe union. You might have a reg on the main line in the house before branching off to appliances. Gas piping plumber should figure this out for you.

busydadof3

This is all there is on the service entrance... if these pictures don't tell me what capacity I have, who can - the gas company I presume?

busydadof3

Just called the gas company, who said I have 'medium pressure' and that 3/4" should not be enough for what I'm running.

??? ???

JUGHNE

You need the pro gas piping plumber to have a look and tell you the situation. You may not have to upgrade the meter unless you have a huge fire pit.

busydadof3

Are there no pro gas piping plumbers here?

Honestly at this point I just want to make sure my house is plumbed correctly/safely.

JUGHNE

They are here, but you need one there, wherever you are. I would say your system is probably OK or you would of had problems by now. In your 4 years of occupancy something would have shown up by now.
Unless we are there to see the complete system, it is pretty hard to make any calls.

ChrisJ

I'm confused.

Are you questioning the line coming in from the road?
My meter is fed with a 1/2" pipe @ 50 PSI.

I have a 1" line going into the building and that 1/2" line before the meter will do far more than the 1" line could ever handle at 6" WC.

busydadof3

Hi ChrisJ, my original question was the 3/4" line going into my house, after the meter. According to the chart I've seen (first result after googling "natural gas pipe sizing"):

http://www.endot.com/OpenFile.aspx?path=21eb7_0.pdf&Type=1&pid=34

My 3/4" run shouldn't be able to support the number of gas appliances I listed in my OP.

I am starting to realize there are differences in pressure - wondering if there's a way to know, based on what I can see in my home and on the meter, what I should be able to support and ultimately if I can add another gas appliance or two down the road, if so can I do it without replacing the 3/4" line (a major project) or do I have the option of T'ing off a separate parallel run to the other appliance?

These may all be stupid questions - I was hoping someone in the know could say "yeah you're piped correctly" or "no, call someone asap". as JUGHNE said I'm probably ok since we've had no issues for the past 4 years. Still would like to be able to definitively calculate my capacity now, whether I can add a branch as-is or if any expansion would require a major headache, in which case maybe I'll just use LP cans for the firepit.

Thanks

ChrisJ

I would follow the chart.
A larger pipe could be run in from the meter and then split off to the old pipe and your new pipe.

Personally, I wouldn't do it outside because that looks bad and neatness counts.

busydadof3

Ok... thanks...........

Steamhead

You should be fine, busydadof3. The 3/4" line coming into the regulator (Pinocchio-like device to the left of the meter) runs under "medium pressure" (maybe 35 PSI or so) so it can handle more gas than the "low pressure" (about 1/4-1/3 PSI) lines that serve the house. The regulator drops the medium pressure to low pressure, then the gas goes thru the meter (which is built for low pressure) and into the house.

If you're wary, have a plumber or gas fitter come in and measure the gas pressure inside the house when all appliances are operating. This pressure is commonly measured in "inches of water column" where 7 inches equals 1/4 PSI. If the pressure doesn't drop below this point with all appliances operating, you're fine.

Then you'd need to know how many BTUs per hour the fire pit would consume, and whether that amount of gas would overload the present meter setup.

busydadof3

Thanks Steamhead, I appreciate the detailed explanation.

I think it's fair to assume I'm fine, given no issues for 4 winters. I feel better knowing there's a reasonable explanation - and I just found another chart that shows modified BTU tolerances depending on pressure setting. I just wish I knew what psi my meter was getting.

Assuming my setup is tested to be fine but not adequate to add a firepit (and future grill), what are my options? My buddy with some plumbing knowledge said I should get the meter upgrade (from 400k to 600k) and have a licensed plumber swap the feed from the meter to 1", then once in the house T off to two 3/4" lines; one to the existing run, and one to support the new appliance(s).

My question is - wouldn't that new 3/4" run starve the old 3/4" run of pressure? Would I need the gas co to increase pressure at the meter, and would THAT require appliance branch regulators be installed on every branch?

Hope you see where I'm going here - if it's as simple as a new meter, a foot of 1" pipe and a T with a straightforward run of 3/4" to the firepit ($$) I'll get it done. If I'm looking at repiping everything and adding regulators, retesting all appliances, etc etc, ($$$$$) I'll run to the LP supplier a few times a year!

Thanks again for taking the time to help.

Steamhead

A 1" line will serve two 3/4" lines. No problem there. But if that were my house, I'd increase the line coming out of the meter to 1-1/4" until it got inside, so it could handle any future expansion needs. This section of pipe is probably rather short, so the extra cost would be slight.

busydadof3

Great, that sounds reasonable - I'll defer to your experience and will get the ball rolling on the project.

I agree on the 1 1/4" to the house - I never have a problem spending extra to future-proof; with 3 young daughters I anticipate my 2x40btu HWTs may not cut it come teen-years. My only concern in this project was doing anything that might cause a safety issue or snowball into a major renovation project due to messing with gas pressure.

Thanks!

JUGHNE

IIWM and the basement ceiling was open I would just run an additional 1" line from meter to furnace/water heater area.
Feed the fire pit from there and leave plugged tee for water heater upgrade for future.

busydadof3

JUGHNE, you're saying you'd T off the new 1-1/4 supply to the 3/4 existing and new 1" run?

I'll ask the pro what he thinks when the time comes - I can get material wholesale so the difference in price would be negligible. I just want it done right - if you can't tell I'm skittish when gas is involved.

JUGHNE

Yes I would, if 1 1/4" is not available from that meter then I would tee there off 1" (I know, I get a little lax as it is just inches of 1 1/4", but it can be a bear in a tight spot).
Gas delivery is dependent upon the 2 factors of pipe size and length of that pipe.
Then with the 1" new run plus existing 3/4" you would be loaded for bear. 3 daughters 3 showers each per day......my brother had 4 girls showering constantly with 3 towels each.....he would just pick up their towels and throw them in the dryer most of the time.....girls don't get dirty at a later age.

Formerly

gas pipe is no big deal in the end, as long as you check your joints thoroughly. Oversize your pipe (and meter) - you will be served better by it (especially since you can get wholesale pricing.) You would be best served by running full sized pipe as far as you can in your house in whichever direction needed and step down in size using a tee for each device necessary.

For example, in my house my gas comes into the basement dead center of my house at 1", and hits a tee to go in both directions at a reduced 3/4. If I wanted to add a house generator (for power outages) on one end of the house, I would best be served by having the full sized pipe running in that direction. The step down to 3/4" robs me of the easy install. Running full size just gives you more options when it comes down to it. If it's no headache, keep the full size as far as you can hang it.

4Johnpipe

The meter regulator says 5-8" water column...

Gordy

That meter is 250 cfh. That's 252kbtus an hour if the btu content of NG is 1011 btus a cf. so no your meter is not rated for 400k. Or did I miss something?

You probably have not noticed a problem unless all gas appliances are running simultaneously. Unlikely.

Tim McElwain

You have a high pressure system with pounds pressure coming in on that 3/4" line probably at 25 to 35 pounds pressure. The meter will only handle about 250,000 BTU's or slightly higher depending on the heat value of your gas per cubic foot typically between 1,000 to 1025 is normal.

You also have a flow restriction ahead of the meter at the outlet of the high pressure regulator which is set to stop flow probably slightly above the rating of the meter so that if a pipe broke the "excess flow feature" will safely shut down the gas.

Your gas company along with your contractor should be able to bring you together with what you need in order to be at full capacity. If they can't do that something is wrong.

The 3/4" line on the service coming in at high pressure is more than adequate for anything you are going to do.

By the way most gas controls today have a built in regulator which will drop the pressure provided at the inlet side of the control to the pressure required and posted on the rating plate of the equipment. Typically for natural gas that is 3.5 : W. C. to 4" W.C.

busydadof3

Gordy said:

That meter is 250 cfh. That's 252kbtus an hour if the btu content of NG is 1011 btus a cf. so no your meter is not rated for 400k. Or did I miss something?

You probably have not noticed a problem unless all gas appliances are running simultaneously. Unlikely.

A couple people commented on the meter handling around 250k btus - According to my gas company my existing meter is an "AL250 with a maximum capacity of 400k BTUs"

I have the option to upgrade to a "ltron 400 meter with a maximum capacity of 600k BTUs"

I'm in the process of trying to find a plumber that's licensed with my town ... the plumber I know and trust that could do this in his sleep isn't licensed in this town and since the fire pit is outside this is one of those 'I should really pull permits' situations.