Nat Gas Fire Pit Help

[Michael Melvin]

Looking for some advise here. I had a 140,000btu stainless steel fire pit installed last fall the flame has never been very high at all (maybe 1-2" tall) and it puts off almost no heat. The manufacturer and the local fore place store I purchased it from said the flames (on high) should be about 10"-12" tall.

After doing a little research it looks like the wrong size line was installed from my meter to the fire pit. It is on a dedicated line and the plumber used 1/2" (yellow coated copper tubing). It is about a 60' run from the gas main where it is tapped to the fire pit.

It looks as though he should have used 1" or even 1 1/2" for that amount of BTU and run length.

My question is can we replace say the first 50' of the 60' run with larger diameter pipe (1"-1 1/2" or larger) and connect it to the 1/2" underground and expect a larger flame with more volume? If so how much more flame 20% 50% 80%???

The problem is the last 10' is 4' under a brand new brick patio and natural stone fire pit. Obviously the first plumber didnt know what he was doing so I'm trying to "fix" this problem. I will have another gas fitment plumber do the work but I just want to be educated on it somewhat so I do not have this problem again.

 

[Plumber69]

yeah you can

 

[Sponsor]

 

[Plumber69]

Did you pay the plumber? Did he have his gas ticket? What other gas appliances do you have? Its possible to put a 2psi meter and regulators on all other gas fixtures. Then you wouldn't have to change the line

 

[hj]

He would only need a single regulator where the existing system connects to the meter, and one at the fire pit.

 

[Michael Melvin]

Plumber69: yes I did pay him, unfortunately. Yes he was licensed (guessing that's what you mean by ticket)

I have a gas fired boiler and gas water heater. (Oven and dryer are electric)

Isnt my problem volume? I guess with more presure you get more volume but at some point you can only get so much volume through 1/2 line.

Is there a way to calculate how many btus I can supply with 50' of 1" pipe and 10' of 1/2 pipe?

 

[Plumber69]

Plumber69: yes I did pay him, unfortunately. Yes he was licensed (guessing that's what you mean by ticket)

I have a gas fired boiler and gas water heater. (Oven and dryer are electric)

Isnt my problem volume? I guess with more presure you get more volume but at some point you can only get so much volume through 1/2 line.

Is there a way to calculate how many btus I can supply with 50' of 1" pipe and 10' of 1/2 pipe?

is it 1/2 od or id

 

[Plumber69]

I think if its 1/2 outside diameter you will only get 110btu thru the pipe if you ran 50feet of 1", if its 5/8th outside you should get 210btu

 

[Michael Melvin]

Plumber69 just measured it with my calipers and it measures 1/2" OD. It's the yellow plastic coated copper tubing.

Two more questions. If my total run is 60' and I do 50' of 1" and say 8' of 1/2" (under the finished brick patio) and 2' of 1" just before it connects to the burner under the firepit insert. Would that help or will the last 2' of 1" not make a differnce? Can I assume I would get even more than 110,000 BTU if I ran 1 1/4" or 1 1/2" or is there a point where it doesnt make a differnce?

Also what equation did you use to come to the two differnt BTU figures you just quoted me? Or was that more of an off the cuff number?

Thank you so much. I really do appreciate your time.

 

[Michael Melvin]

To clarify I measure the just copper part when measuring OD. So it's a little larger OD if you include the yellow coating or cover

 

[Plumber69]

not going make a dif if you go bigger then 1 inch. Not going help going 1 foot of 1 inch in burner

 

[Plumber69]

The 1 inch will have to come right from meter withen a foot, with nothing else coming off of it after that

 

[Michael Melvin]

Is there a way you can explain to me how you came up with the BTU measurement?

 

[WorthFlorida]

The pipe sizing charts for cubic feet of delivery may help in your determination. The URL is below.

From these charts about the most you can get from a 60' 1/2 pipe is about 76 cu. ft. per hour. For a 10' length is from a meter, not a pipe 50' from the meter and the 10 feet is from the meter with a little less than 2 PSI. At the end of a 50 feet from the meter to down size to 1/2, you need to know the pressure at this point. But looking at the chart, a 50' 1" inch pipe to 1/2 pipe for 10 feet may do the trick. I have never looked at this before and I'm not a plumber.

https://www.edcgov.us/Government/building/documents/Gas Pipe Sizing (Natural).pdf

I google searched, btu's per cubic foot of natural gas.
In 2017, the U.S. annual average heat content of natural gas for the residential, commercial, industrial, and transportation sectors was about 1,037 Btu per cubic foot. Therefore, 100 cubic feet (Ccf) of natural gas equals 103,700 Btu or 1.037 therms.Oct 16, 2018
https://www.eia.gov/tools/faqs/faq.php?id=45&t=8

 

[Plumber69]

Theres a whole seperate chart for copper gas lines