According to my Ohio code book 3/4" steel pipe at 100 feet will carry 104,000 btu/cuft. If you want to add anything
down the road you might consider 1" piping.
down the road you might consider 1" piping.
Gas line - Max BTU on 60' 3/4" pipe
- Thread starter auradeus
- Start date
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you said you had 2 1\2" tees after exiting cook top.
If you run 1/2 to Grill with 100 btu which would calculate to 95 CFH you would need 3/4" pipe just for the BBQ.
You max out at 66 CFH on a 1/2" pipe which is about 69k BTU grill. You sure you need that much for the grill.
3/4" line will handle only 138 CFH with a total developed length of 60 ft.
Add a cook top and you're maxed out for the 3\4"
Check you grill btu.
You already have 36k btu + 26k btu on a 45' line which is about 62.8 CFH plus one more appliance you said you had two 1/2" tees???
To do a better calculation make a rough sketch.
only need ft between each branch.
Branch size and appliance input BTH/hr
Probably okay with what you already have but the BBQ is not going to work with a 1/2" line or a 3/4" if it is as big as you thought
If you run 1/2 to Grill with 100 btu which would calculate to 95 CFH you would need 3/4" pipe just for the BBQ.
You max out at 66 CFH on a 1/2" pipe which is about 69k BTU grill. You sure you need that much for the grill.
3/4" line will handle only 138 CFH with a total developed length of 60 ft.
Add a cook top and you're maxed out for the 3\4"
Check you grill btu.
You already have 36k btu + 26k btu on a 45' line which is about 62.8 CFH plus one more appliance you said you had two 1/2" tees???
To do a better calculation make a rough sketch.
only need ft between each branch.
Branch size and appliance input BTH/hr
Probably okay with what you already have but the BBQ is not going to work with a 1/2" line or a 3/4" if it is as big as you thought
Artie_T
Member
Hi Auradeus,
When I wanted to replace my 100,000 BTU on demand hot water heater, I was also having a hard time trying to understand the gas pipe size issue. Three companies tried to sell me a 199,000 BTU water heater and said I would need to replace all my gas piping. Using the link below I was able to get a better understanding of my gas pipe issue and then get companies in to price out the cost to install a 150,000 BTU water heater without having to change any of the gas piping. Saved a lot of money and still enough hot water to have both showers going at the same time.
https://www.kingcounty.gov/depts/he...th/piping/plumbing/installing-gas-piping.aspx
I know this is not for your area of Massachusetts, but it may help you get a better understanding of what the honest pros here recommend and are explaining.
Also each appliance should have a plate attached that identifies the Max BTU's for the unit. Knowing this number will make a big difference in what you can or can not do and what you MUST do to have your situation work safely.
When I wanted to replace my 100,000 BTU on demand hot water heater, I was also having a hard time trying to understand the gas pipe size issue. Three companies tried to sell me a 199,000 BTU water heater and said I would need to replace all my gas piping. Using the link below I was able to get a better understanding of my gas pipe issue and then get companies in to price out the cost to install a 150,000 BTU water heater without having to change any of the gas piping. Saved a lot of money and still enough hot water to have both showers going at the same time.
https://www.kingcounty.gov/depts/he...th/piping/plumbing/installing-gas-piping.aspx
I know this is not for your area of Massachusetts, but it may help you get a better understanding of what the honest pros here recommend and are explaining.
Also each appliance should have a plate attached that identifies the Max BTU's for the unit. Knowing this number will make a big difference in what you can or can not do and what you MUST do to have your situation work safely.
Hello Auradeus.
Total developed length from your meter/ regulator to the farthest fixture should be established first.
Second part to the puzzle would be total btu's used combining every fixture on system.
NG (natural gas) in most cases is .5 lbs pressure and propane (LP/liquid petroleum) is 2.0 lbs's.
For each fixture you wish to add you must add the length to your total developed length and the btu' to your total btu's.
Once this is established you can use the gas chart to determine if your piping is sized to accommodate added fixtures.
The problem with under sized piping is that you could easily starve out your system when using multiple fixtures and once which is quite possible.
I hope this helps and does not confuse the issue.
Total developed length from your meter/ regulator to the farthest fixture should be established first.
Second part to the puzzle would be total btu's used combining every fixture on system.
NG (natural gas) in most cases is .5 lbs pressure and propane (LP/liquid petroleum) is 2.0 lbs's.
For each fixture you wish to add you must add the length to your total developed length and the btu' to your total btu's.
Once this is established you can use the gas chart to determine if your piping is sized to accommodate added fixtures.
The problem with under sized piping is that you could easily starve out your system when using multiple fixtures and once which is quite possible.
I hope this helps and does not confuse the issue.
Diehard
In Remembrance
The Grille was revised to about 40k btu back in previous comments.
Also, FYI...The typical Natural gas pressure in a home is NOT 1/2 psi in Massachusetts. That's our Maximum allowed. It is typically much less than that. But none the less we are required to use 0.5" WC pressure drop.
Also, the typical method used to size gas piping is the Longest Length Method. This is a conservative method and need not include fittings or change in direction.
Diehard
In Remembrance
I believe you have it confused. it's not the "Total developed length" but rather the "Longest developed length" that is used. That's the column in the chart you use for sizing all the branch piping for that specific branch load.
The "total btu's used combining every fixture on system" only applies to sizing the main line that must carry that total load.
It can be confusing.
Total developed length + btu will always dictate what minimum size your service can be AND how far you can run a line without having to upsize due to load.
You have to calculate entire system in order to add fixture OR add length.
Your regulator at the service meter
You have to calculate entire system in order to add fixture OR add length.
Your regulator at the service meter
Around here you can run the inside main line 1" 40 ft to the first appliance. Over 40ft it has to be 1 1/4". This is at medium pressure. He could
branch tee's off the main for each appliance and not have to worry about a thing. But, if I am reading his thread correct he is running all
these appliances off of one branch line of 3/4" which is really cutting it close.
branch tee's off the main for each appliance and not have to worry about a thing. But, if I am reading his thread correct he is running all
these appliances off of one branch line of 3/4" which is really cutting it close.
When installing a gas system we like to first determine the total btu count then measure the distance (total developed length)between the meter and the farthest fixture.
This is the deciding factor in what size the service needs to be and also how far we need to extend that size pipe before reducing down.
If you have a 1" service feeding a w/h, furnace and a range and are maxed out in distance you can not branch off of anything without compromising the Integrity of the entire system.
Not so confusing.
This is the deciding factor in what size the service needs to be and also how far we need to extend that size pipe before reducing down.
If you have a 1" service feeding a w/h, furnace and a range and are maxed out in distance you can not branch off of anything without compromising the Integrity of the entire system.
Not so confusing.
Diehard
In Remembrance
It is calling it close relative to the chart for max. of 0.5" wc pressure drop.
On the other hand we don't know what his service pressure actually is. So he could be dropping 0.6" wc of pressure and still have what he needs as a minimum at the points of demands. Additionally, as I mentioned, it is a conservative method.
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I have plumbed a hand full of jobs with a 5 lbs NG system.
Would be much easier to add appliances with that system opposed to a half pound system.
Definitely, We have some high pressure lines out in the country but not in the city area.
chiraldude
Hardcore DYI-er
1/2 psi is for safety. If you had 20 psi you could run everything off a 1/4" pipe but a pinhole leak at 20 psi could blow your house up in a few minutes whereas at 1/2 psi you will have lots of time to notice the smell before it gets dangerous.
For each fixture you wish to add you must add the length to your total developed length.
That's not correct. Let's say you cut in a tee in the middle of an existing system to add something.
The length of that additional appliance is only a factor if it is the farthest appliance in the system.
If the original system's farthest appliance was say 60ft from meter and the new appliance is only 50 ft from the meter,
you don't add the length of the new line to the total developed length.
But you will calculate pipe size for the added line from the meter to the farthest appliance on that new branch line. After you calculate line A to farthest fixture.
There could be more than one appliance added to new branch line. So you have to size the line going to the farthest appliance 1st on any line.
Then you work your way back and add any branch lines and CFH for appliance .
If your new line is 70ft, then that now is the farthest appliance in the system and the sizing calculations start there.
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