gas meter pipe size

Koan · October 2016

@adambnyc , @delta T I assume from the meter plate (picture above) the meter capacity is 415,000 BTU ??

Koan · October 2016

@adambnyc , @delta T I assume from this name plate the meter capacity is 415,000 BTU??

delta T · October 2016

Yes, while technically you are over that load, you are not excessively over and the only thing realistically that would happen would be a slightly higher pressure drop at full load (maybe up to a 1" drop through the meter as opposed to a .5" drop). The tables in the IFGC say that for schedule 40 steel, NG, at less than 2psi static pressrue, you will incur a .5" pressure drop in 10' of 3/4 if you run 360 cu ft. per hour (~360,000) so running everything you have simultaneously will incur a drop higher than .5" but probably still acceptable. I would say worst case scenario you will have no more than a total drop of around 2" between the meter and the section of 3/4" running everything simultaneously. Assuming that the rest of the piping is sized to be less than a .5" drop then you will be fine as long as your static pressure is high enough (7-8" incoming should ensure enough pressure at all times to every appliance. I notice there is no regulator by your meter, do you happen to know what the pressure is coming in to your house? If you have lower pressure, I would change the pipe out and make it right.

adambnyc · October 2016

Just looked back over the thread and noticed the boiler size. That's a pretty serious boiler. Was curious how many rads you had attached.

Also, I just wanted to make mention that the 1 1/4 gas line feed may very well have an inner tube of a small diameter. So the actual line could be 1" or even 3/4.

That was the case in my house. From my understanding, PSEG ran new gas lines about 20 years ago and the practice was 1 1/4 pipe with an inner tube.

I was lucky enough that when I did my oil to gas conversion that PSEG had to redo my consumption numbers. I knew I was going tankless, so I just told them the additional BTU and they upgraded the line at no cost. Small victory

Koan · October 2016

@delta T Don't know the feed pressure, would guess 2psig but you are correct there is no regulator. I figured I was just under the load at 405,000 BTU (300,000 boiler, 40,000 HWH, 35,000 dryer, 30,000 cooktop). Even though the inlet is reduced a little I was thinking I'd fix the outlet side but leave the inlet side as is so I don't have to find the outside shut off. At least that way I can just use the existing valve to shut everything off. Next I'll change the outlet diameter to that of the S fitting on the meter ( I assume that is 1-1/4) and use a good 1/4 turn gas ball valve in the outlet pipe and clean up the manifold and piping a bit.

Koan · October 2016

@adambnyc There are 11 radiators with a surface area of 399 square feet. The boiler is rated for 750 square feet so it is completely oversized. There is a chance it is downfired at lower than the 300,000 BTU but I will clock the meter to check once everything is running again to see what it is actually using.

keyote · October 2016

in nyc the utility would own the work before the meter.That not going to be easy to straighten out. I would make certain its really necessary even if it meant not running the dryer on thankgiving while everything else is maxed out it would be worth not messing with, especially since you got to wasting more gas every year with that boiler than it would cost to change the pipe. unless its a castle. my three family 4500 sq ft 100 year home has a heat loss of 52 KBTU and I have a 85 KTBU 10-1 modulating boiler. and that because I have an indirect DHW tank

ChrisJ · October 2016

keyote said:
in nyc the utility would own the work before the meter.That not going to be easy to straighten out. I would make certain its really necessary even if it meant not running the dryer on thankgiving while everything else is maxed out it would be worth not messing with, especially since you got to wasting more gas every year with that boiler than it would cost to change the pipe. unless its a castle. my three family 4500 sq ft 100 year home has a heat loss of 52 KBTU and I have a 85 KTBU 10-1 modulating boiler. and that because I have an indirect DHW tank

My 150 year old 1600sqft single family home loses about 72K @ -8F with an indoor temp of 72F and my house is no castle.

While I realize my loss is quite high for the size building, 52K for 4500sqft seems incredibly low, even for the NYC area?

keyote · October 2016

I have triple pane windows with krypton, closed cell spray foam insulation,and my design temp in brooklyn is 17 degrees F. Im also although detached its four stories town house so less roof per sf, and a basement is part of that and is 2/3 below grade. and although detached its anly an alley so much less wind and its 3 wye brick behind the spray foam. Im converting to radiant as i renovate i have pics of the boiler KHN 085 I just installed up.
However I get your point mine is not likely to be a direct comparison,But you're only 72k and hes got a 400k boiler! and be surprised if he need more than a 125k unit and not surprised if he only need a 75k unit. if so for less time and money than replacing those in between gas connections he could pick up a newer smaller unit on craigs list and install it, and save money every month as well.

ChrisJ · October 2016

I'm not sure in other areas, but in mine the gas company said they'd be more than happy to upgrade me to a larger meter if I want more gas.

The difference is I have a 1/2" 50 PSI line coming in so they wouldn't need to change that, only the meter.

keyote · October 2016

I have never heard of gas at that kind of pressure sounds dangerous even with propane they reduce the pressure outside before coming in, here we test at 3 psi for .5 psi service if the pipes been painted they can make you test at 20 psi and that usually means having to repipe because most old gas threaded pipes are not going to hold 20 psi

ChrisJ · October 2016

It's 50 PSI to the regulator at the meter outside. 6" after.
I had them run the gas in 2011. Last fall I had a guy from the gas co come out to check the pressure and he told me it was 50 PSI to the meter. I was amazed, and his response was "Oh yeah, you'll know if it leaks". It's a 1/2" plastic line with a yellow wire wrapped around it.

Have a look at the pictures at the link in my signature. There's a picture of the gas meter setup there as well.

All of the gas piping I ran was tested at 40 PSI. Unions and all.

SWEI · October 2016

25-75 PSI is pretty standard in modern gas mains.

keyote · October 2016

I tested mine at 20 anyway but when i bought the house the owner had the gas turned off during contract and couldnt get it passed to turn back on so had to run a new line for old boiler to get through closing.
Thats an impressive install you did.

Paul48 · October 2016

I could see a trunk line at that pressure. I'm amazed that a gas company would deliver 50 psi to the door of a residence. I don't doubt it, but that's a little scary.

delta T · October 2016

Where I'm at it varies between 40 and 60 psi to the reg, then down to 6" into the house. Kind of scary when a regulator goes, I have definitely seen it a few times...at least the utility does usually pay for new gas valves on appliances when the regs do fail.

ChrisJ · October 2016

delta T said:
Where I'm at it varies between 40 and 60 psi to the reg, then down to 6" into the house. Kind of scary when a regulator goes, I have definitely seen it a few times...at least the utility does usually pay for new gas valves on appliances when the regs do fail.

What happens? Do the CGVs have an overload that shuts the valve off?

Koan · October 2016

The more I look at this piping the more I see how poorly it is done. I really don't want to get into anything before the meter, besides, I'm not sure how to shut the gas off outside! The feed to the house is 1-1/2", then goes down to 1" through the main valve then back to 1-1/4 " into the meter.

For the inlet, I backed into the Spitzglass formula and put it in Excel. 3 90 deg ells for 1" pipe is 7.8 equivalent feet. there is not much pipe so assume 8 feet of 1" pipe. with all things firing at once (397 CFH = 397,000 BTU/hr) that pressure drop is 0.21" wc.

Not great but nor horrific. Does pressure drop before the meter even matter??

For the 3/4" pipe out of the meter with the 90 ell that would be about 3.1 equivalent feet. That means at full load I lose 0.33" wc for that section alone. Since these together are over 0.50" wc, I have to hope prior to the meter does not matter.

Either way, I am thinking I will run the 1-1/4 for the 300MBTU/h boiler right into a 1-1/4 valve then into the meter and then tap off the 1-1/4' for the HWH, Dryer, and cooktop. The only run of any length is the 3/4" cooktop at 30 feet with 3 tees and 4 ells for a total of 50 equivalent feet and even at 35MBTU/h (35CFH) the drop is only 0.04"wc

BTW Baltimore city requires a 30 psig test.

looking forward to the feedback!

bob_46 · October 2016

Maybe you are in an area that still has low pressure district regulation where there is not a regulator for each building.

Charlie from wmass · October 2016

The large supply pipe to the building would be an indicator of that

Koan · October 2016

I do think we are in such an area. I guess that means sizing the pipe better be right cause there cannot be an increase in pressure!

Tim McElwain · October 2016

If I were you I would get in touch with your local gas utility to insure what you are working with. Then do a pipe sizing set up in line with NFPA 54 pipe sizing charts. I can help you with that if you draw up a piping plan showing lengths of pipe and appliance load at the end of each run. As to gas pressure get a manometer and measure pressure after the gas meter. It looks like this is a low pressure piping system from the utility so you should have between 7" W.C. to 10" W.C. (less that 1/2 a pound) after the meter. This should be adequate if the outlet piping is sized correctly. I would suggest using the chart in NFPA 54 which allows a pressure drop of .3" W.C. and no more that another chart which allows .5" W.C.

Koan · October 2016

Good advice @Tim McElwain . I think I'll leave the inlet side alone, run 1-1/4 to the meter and then branch off wit 3/4 after the Furnace. Earlier in this thread you can see the choke point of a 3/4 pipe and an ell then a tee then up to 1-1/4. Makes no sense. I have the loads listed earlier in the thread as well, the boiler is 300MBTU/H, dryer 22, water heater 40, cook top assuming 35. Longest run is cook top at 50'.the other loads are all no more than 25 ', and the 1-1/4 goes only to the furnace. I calculated the pressure drop and they are a good deal smaller just by running the 1-1/4 right to the meter, then using reducing tees off the 1-1/4 for the smaller loads. I'll try to draw it up. Been using the table you suggested as a guideline.. 0.3 " drop, 2psig or less sch 40 . Got from the IFGC, but I checked with NFPA and it is the same. Thanks for the help!

delta T · November 2016

ChrisJ said:

delta T said:
Where I'm at it varies between 40 and 60 psi to the reg, then down to 6" into the house. Kind of scary when a regulator goes, I have definitely seen it a few times...at least the utility does usually pay for new gas valves on appliances when the regs do fail.
What happens? Do the CGVs have an overload that shuts the valve off?

@ChrisJ Usually when the reg fails, I see about 1-2 Psi coming into the house, which is still scary, but not 60. I don't know if the regs are just designed that way, but I have never seen it go over that in the house. It does fry gas valves though, they are not lying about the 1/2 psi max....

Tim McElwain · November 2016

Most redundant gas valves (required since 1979) have as the first valve a direct acting solenoid valve which will not open if gas pressure exceeds 1/2 pound (14" W.C.) on older single seat valves excessive pressure will however damage the valve.

A lot of new setups from utilities have excess flow valves which will shut down if excessive flow due to over pressure or a break in the piping system.

Koan · November 2016

in looking for a 1-1/4 quarter turn valve to mount coming out of the meter, the only ones I can find specifically for gas have a pilot tap I do not need, and they are very expensive. Can I use a normal threaded quarter turn valve?? I have linked to both:

supplyhouse.com/Apollo-Valves-50GB6A1-1-1-4-Gas-Shut-Off-Ball-Valve-1-4-Tap

supplyhouse.com/Watts-0555105-LFFBV-3C-1-1-4-Full-Port-Threaded-Ball-Valve-Lead-Free

so can I use the second one as a shut off on the outlet of the meter? There is no valve there now at all, just one on the inlet side.

Tim McElwain · November 2016

That is not required as long as there is a shut off before the meter. There should then be shut off within 6 feet of the heating and hot water. All other appliances should have shut offs as close to the appliance as possible.

Koan · November 2016

@Tim McElwain Thank you sir!!! One less thing to worry about!! Just to be safe I would like to take you up on the offer to review the proposed pipe diagram please. I think it is ok, but I want to make sure I am not screwing up something. I want to make allowances for potential future changes as well. I'll try to diagram the current mess along with proposed changes. Thanks Tim

Tim McElwain · November 2016

Send it to my e-mail address gastc@cox.net.

Koan · November 2016

thanks Tim!

Formerly · November 2016

Tim McElwain said:
Send it to my e-mail address gastc@cox.net.

just a PSA: spam bots spider through web sites and will add your email if you give it out. next time, spell portions of it (gastc AT cox DOT net) Not a big deal if you use gmail, but with cox, not sure how good their spam filtering is.

gas meter pipe size

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