gas meter pipe size

keyote

I think i know the answer but am hoping i dont. just tied in two new risers which was a bear having to cut in and use left right nipples 4 inches apart. dont worry i kept gauges on all four sections simultaneously while i worked to make sure if they ever lost pressure id know where the problem was everything held 3 lbs the whole week i was working on it.I bought this 100 year old house which i think was previously used as the museum of worst construction practices and how to kill people. The meter was actually hanging from a vent line with a old rope when i closed. It was so scary i could hardly bare to look at it but did manage to hang the vent with clevises instead of friction the clevis to upside down clevis down to the pipes on either side of meter. it was still to scary to look at but had to shut down the gas and swing it out of way for the first test gauge to get my work done. which is when i realized the line coming in was 1 1/2 then reduced to 1 1/4 for no apparent reason ok no bigggie, because the 20" run from the meter to boiler room which i had to cut into was a new run of 1 1/4 put in while i was in contract because stupid owner stupidly shut off heat to save money on empty building despite my protests and when pipes burst and wanting the gas turned back on the 100 year old painted pipes failed utility test and he had to pay to re run that line so i could get a loan, i found a licensed contractor for a good price since a permit and inspection were then required. what i never noticed was the 1 1/4 pipes on both sides of meter are bushed down to 3/4 where a special S shaped fitting that has a gasketed compression on one end for meter attach. my question is isnt that reduction to 3/4 on both sides of meter effectively giving me 3/4 service or is there some special law of venturi for gas meters and i dont need to make the utility repipe the damn meter head and recap and test the whole house all over again it would be nice to get it done properly but of course that work was done by the utility to begin with which is scary.

Koan

@Hatterasguy

I have a similar situation but my run is for one foot. Gas main feed is 1-1/2", reduced down to 1" pipe in to the meter, comes out and goes from 1" down to 3/4 " for a foot, then back to 1-1/4".

I think @keyote is wondering the same thing I am - is there any good reason for this? like - somehow is it important to keep the velocity in the out-pipe from the meter high or something silly like that.

Is there any reason to remove and replace the 1' of pipe with something larger, or is the pressure drop overt that one foot of 3/4" pipe not meaningful?

Thank you!

SWEI

It's possible the meter was upsized at some point. Very common to see a small meter outlet coupled to a larger main trunk line (1" or 1-1/4" meter outlet feeding 4" main is not unusual on commercial jobs.)

keyote

I have since found any plumbing supply has all the meter parts in matching sizes from 3/4" up to at least 2" on display

delta T

Really we need to know the connected load, the length of the pipe supplying said load, and the operating pressure. If we have that, we can tell you for sure there will be nothing wrong.

Gas meters do have limits to how much gas they can allow through at a reasonable pressure drop. The meter should have a number on it like 250 or 450 which would be the maximum rated load in cu ft per hr. (general rule of thumb is 1000 btu/cu ft on gas, actual number will vary depending on local utility and altitude but 1000 will get you pretty close)

As has been said before, the 3/4 reduction will not materially affect the gas supply pressure unless there is a large load connected.

Koan

@delta T @Hatterasguy
Thank you gentlemen. I will look tonight and add pictures. The piping seems a bit messy.

I do know we have a gas cook top, gas dryer, gas hot water heater, but mostly an oversized gas boiler (300,000 BTU) See attached

delta T

Take a picture of your meter too if you can....

Koan

@delta T
LOL - sorry i had this pic of the boiler ID handy. It is clearly not the Gas meter about which I wrote. I'll try to p[osdt a pic of that tomorrow

delta T

No worries, thanks for the boiler info, just want to see what the meter capacity is. You would be surprised how many times I run into an issue caused by the fact that someone added an addition or something, changed the boiler, added a firepit, a barbecue, a snowmelt system and a pool heater, and even with all the people involved, no one (including the city inspectors) noticed that the meter was only rated for 250,000 btuh and now they have 750,000 btuh connected. of course any problems usually only show up randomly when enough things are all running at once.

At a guess using what you have given us @Koan you have somewhere around 440,000 btuh connected, so 1 1/4 sch 40 steel pipe should adequately supply that with minimal pressure drop (less than 1/2" WC) in anything under 80' of piping, and the same is true for 1" sch 40 pipe anything less than about 20'.

Unless the meter itself is undersized, the 3/4 pipes will not materially affect this in either case for @Koan and @keyote, but it never hurts to check.

BTW the numbers I used assume a standard 40 or 50 gallon water heater at 40,000 btuh input. Unless you have a huge commercial water heater it should be close.

Koan

@delta T Here are the pics.
The HWH is 40 gal, though a bit undersized, standard cooktop, gas dryer.
When the burner on the boiler starts the meter clicks away like a bad hard drive!
You can see the piping is a bit funky, but since it is parallel to different devices I assume this is lowering any back-pressure.
The first pic has the piping labelled. Thank you!

Brewbeer

The 3/4 inch pipe off the meter, into a 90 elbow, and then through a T for the other loads, before upsizing, seems like it would be too much restriction for the boiler, especially if the WH (~40,000 BTUs), dryer (~35,000 BTUs), and/or cook top (~30,000 BTUs?) are running at the same time as the boiler (300,000). You might only have 2 feet or so of 3/4 inch pipe before increasing to 1 1/4, but the fittings add significantly to the pressure drop.

There are a few ways to size natural gas pipe, but a quick way to do an initial check is the Engineering Toolbox: http://www.engineeringtoolbox.com/natural-gas-pipe-sizing-d_826.html

keyote

wow thats some scary looking gas piping you have unions all over the place they're illegal on gas pipe except right at the boiler and hot water heater as disconnects, galvanized pipes illegal most places as well and i dont like that valve at the meter. Im not a plumber so take it with a grain of salt and honestly theres lots of scary looking piping and electric out there maybe half of it.

Koan

@keyote
Yup it is a mess. this is how I found it. The wires nearby are low voltage dormant alarm wires. I would love to unravel the gas lines from intertwining through the water plumbing. Looks like a gate valve to me. I want to clean all this up, but first want to make sure I don't need a new meter. The existing one is from 1968

@Brewbeer
I think my only benefit is that the lines are parallel out of that "manifold". I seem to remember this helping to lower resistance. But you bring a good point into play, everything goes through 1' of 3/4 pipe, a 90 el, and a tee.

I looked at the engineering toolbox and it looks like the the 1' of 3/4" sch 40 pipe is not an issue, now I will find the equivalent pipe length for a 90 el and add it in. 1' of 3/4 pipe @1/2" WC pressure drop is 860 CFH, so I figure even half of that is less than my max load. Another 20' of 1-1/4 pipe is 849CFH at a 1/2"WC drop, so that part is negligible.

Does anyone know where I can get info on drop across fittings?

ChrisJ

Unions illegal in most places except at the appliance?
I'd have to argue that. In fact, I've never heard that before.

I also believe many, if not most places allow galvanized pipe.

keyote

well chris you can argue it and you might be a plumber and Im a tinknocker thats simply done a lot of plumbing and building, but i dont think you would win that argument,left right nipples only in new york

ChrisJ

keyote said:

well chris you can argue it and you might be a plumber and Im a tinknocker thats simply done a lot of plumbing and building, but i dont think you would win that argument,left right nipples only in new york

I'm willing to bet I most certainly will win it.
You said they're illegal in most places. That is saying in the 50 states on the US they're illegal, except near the appliance.

I'm going to bet most places in the US, except perhaps Massachusetts, California and a few big cities don't care where you put them.

@Charlie from wmass Can you comment on Ma code?

ChrisJ

@keyote for the record, I'm not a plumber or a tinknocker, I don't even play one on tv.

Wish I was though.......

Koan

I thought I read a dielectric was required? I see one in my system (see pics). You can't both require and not require a union at the same time. I also understand codes vary, and practices certainly do , in different jurisdictions.

Charlie from wmass

Unions legal anywhere except in the appliance jacket. If they are concealed they must be punched on the union nut to lock it in place.

keyote

its true NYC has the most stringent codes but we have them for good reasons and have the most experience.I admit I think some are even overkill at the residential level, But i dont think not having ground unions hanging from vibrating floor joists is one of those instances.
So youre not even in construction dont pipefit for a living or deal with inspectors regularly but have strong liberal opinion on this gas safety issue? love the internet.
never heard of a need for dielectric on gas even on water with different metals their use is dubious. the meter itself has union fittings with rubber seals so new york may have solved it at the meters if it was an issue., maybe its because of the galvanized pipe which stopped being used because it flaked off into burners and stuff.

Charlie from wmass

Dielectric unions required outside where pipe leaves ground to go to meter. Unions are legal , if there is a chance of them vibrating loose they need punched. All this said I use unions only when absolutely necessary.

Charlie from wmass

Galvanized pipe is only legal on long Island outdoors. Every where else it is illegal. Pipe sizes near the meter can be quite small. It os all about pressure drop and gas flow. That is why 3/4" pipe at a meter with 250mbtu flow is normal.

keyote

In NYC theyre starting to require all gas pipe in same room as boiler be welded, and have a fresh air and negative pressure from rest of cellar. That seems like a bit much now, but welcome to NYC.

Charlie from wmass

Great welded , because that has never leaked. Eye roll.

ChrisJ

It's impressive that NYC has stricter and apparently even sillier codes than Massachusetts.

Charlie from wmass

New York City had code first. Massachusetts tried to emulate New York City with our plumbing code.

Paul48

Neither ever considered they would be getting ground joint unions from China.

ChrisJ

keyote said:

its true NYC has the most stringent codes but we have them for good reasons and have the most experience.I admit I think some are even overkill at the residential level, But i dont think not having ground unions hanging from vibrating floor joists is one of those instances.
So youre not even in construction dont pipefit for a living or deal with inspectors regularly but have strong liberal opinion on this gas safety issue? love the internet.
never heard of a need for dielectric on gas even on water with different metals their use is dubious. the meter itself has union fittings with rubber seals so new york may have solved it at the meters if it was an issue., maybe its because of the galvanized pipe which stopped being used because it flaked off into burners and stuff.

Strange that being the case the information I provided was more accurate than what you gave. Really, it's up to the guy doing the work to make sure he is code complaint in that specific area, not those on a forum. We try to help to the best of our ability (for free) and never intentionally give wrong information.

No, it's not my "liberal opinion on gas safety" it's what's required by code in most of the country. That's a fact, not an opinion. For some reason you're attacking me over not being a plumber and yet you're a tinknocker giving advise on gas piping? We all do our best to help each other, no matter what our profession.



I used to be in construction but had to get out due to medical reasons.

I hope you enjoy the rest of your evening.
Be safe.

Charlie from wmass

The funny thing that this whole post was actually answered by @Hatterasguy as the first answer on the thread. Guess what he is not a plumber either.

keyote

and as a tin knocker i install gas furnaces, kitchen equipment, gas air curtains, .and attend constant job meetings on major projects for 35 years so I know a thing or two, but was honest enough to add my disclaimer.
I am aware some areas allow all sorts of unsafe practices still this particular practice i am fairly well versed in and can anecdotally attest "most" is a fairly accurate statement for places that do not allow except at appliance. I could add that of those that do, none allow them to be concealed, which tells you something about the reliability of ground unions,
then you can talk to guys who use them and they will give you the hundreds of methods they use to make them safe, the secret sealants, the moving the wrenches around to avoid ovalling while tightening, the heating the outside before tightening, the tapping on the union while tightening the marking the union to detect movement the punching, the thread killing, the vibration hanging methodologies,and on and on.
yeah i gave my opinion with a caveat

Charlie from wmass

Okay I guess I will need to pull out NFPA and quote chapter and verse. By the way the original question had nothing to do with unions it was about pipe sizing near the meter. My statement about using a punch on a union it's not opinion it is written into the code. The use of any sealant on a ground joint Union is prohibited. The only thing that ever to go onto a ground joint Union maybe a drop of oil to lubricate the threads.

ChrisJ

Charlie from wmass said:

Okay I guess I will need to pull out NFPA end quote chapter and verse. By the way the original question had nothing to do with unions it was about pipe sizing near the meter.

I'm over it.
Let's move on. We shouldn't be arguing anyway.

rick in Alaska

Unions are only allowed here if they are on the backside of a valve, and I am not sure about this because it hasn't come up yet, but I am pretty sure only outside. Personally hate them.
I have also only been using galvanized pipe on all my gas jobs because of our salt environment here, and the fast that the black pipe we get looks bad in about a week.
Rick

ChrisJ

I ran black iron for the air compressor at work and have no leaks not even at unions at 140 psi.

I've personally never had a problem with one. Don't buy Chinese garbage and that goes for all of the fittings not just the unions.


I'd rather unions than flex pipe or that corrugated stuff on gas piping. I realize in some areas code requires a flexible connection at an appliance, but I'd rather have a union and solid pipe my self of code allows.

Paul48

His statement about unions was true with the older codes, even in MA. A lot of the codes have changed, to allow them only when there is no other choice. You know how that works.......they'll never pass them. I'm not so sure I agree with relaxed codes. But that is just opinion and worthless. The bottom line..........you have to know the code for the area you're working in.

ChrisJ

Paul48 said:

His statement about unions was true with the older codes, even in MA. A lot of the codes have changed, to allow them only when there is no other choice. You know how that works.......they'll never pass them. I'm not so sure I agree with relaxed codes. But that is just opinion and worthless. The bottom line..........you have to know the code for the area you're working in.

Absolutely.
And by following local code an inspector won't have a leg to stand on if he gives you a hard time over something. It may suck to deal with, but as many have said on here repeatedly, inspectors enforce the rules, they don't get to make up their own.

Paul48

Just remember.....the other trades think those are ladder rungs. What's the saying?.....Ya can't fix.......

keyote

my experience is inspectors absolutely have broad latitude most codes explicitly give them that. and even when they dont its like arguing with a cop about a law. In new york we budget millions in a project for DOB contingencies and DOB is only one agency we have to satisfy, fire dept, landmarks, the utilities get veto over all boiler room work, DEP, this list is endless.whatever i know this no ones putting one in my house.

adambnyc

In NJ my local plumbing inspector said gas unions OK as long as you don't bury them. They must be accessible just like a junction box.

I installed a Rheem tankless last year. 199,000 BTU. Needing to upgrade meter, which required whole gas line both outside and inside to be completely redone. Was a big job.

SWEI

adambnyc said:

In NJ my local plumbing inspector said gas unions OK as long as you don't bury them. They must be accessible just like a junction box.

Almost the same interpretation here: Gas unions must be visible, so not OK to put them above a drop ceiling. Oh, and no street 90's on gas.

ChrisJ

SWEI said:

adambnyc said:

In NJ my local plumbing inspector said gas unions OK as long as you don't bury them. They must be accessible just like a junction box.

Almost the same interpretation here: Gas unions must be visible, so not OK to put them above a drop ceiling. Oh, and no street 90's on gas.

Depends on the area.
Street 90s are often even used by gas companies. I used one to pipe my gas meter into the house and it passed inspection fine. Guy from the gas company was out last fall to check the gas pressure and even touched up some of the paint for me, no issues.

I can't remember who, but I just had this discussion with someone. Maybe @Charlie from wmass .


Some places don't allow plugs or close nipples either, others do. The inspector I had wanted a short nipple and a cap, not a plug so that's what I did.


I believe the reason unions cannot be buried is because someone could accidentally loosen one while working on a pipe and not realize it even exists. Not because they're dangerous.