Gas piping csst questions

[Lefebvres090428]

I want to run a section of csst for natural gas to my stove area before I have a plumber test and hook up. The main line comes in from the regulator via black iron and then pretty much Immediately goes to 3/8 copper and runs along the wall for about 15 ft where it turns and runs into the gas fireplace on the other side of the wall. Can I tap into the copper to run the csst up the wall to the attic where I will then run it down the wall to the stove? Or is the 3/8 copper line not sized big enough for the two appliances and I need to run the csst back to where the black iron comes in and tee off of that? Do I need to run the csst inside conduit when ran in a garage on the exterior of a wall inside the garage?

 

[John Gayewski]

You should run the csst all the way to the black iron pipe. Get rid of the copper pipe. Usually csst is only ran overhead and converts back to black pipe at the appliances.

 

[Sponsor]

 

[Lefebvres090428]

You should run the csst all the way to the black iron pipe. Get rid of the copper pipe. Usually csst is only ran overhead and converts back to black pipe at the appliances.

Thank you! Since the copper pipe is run in the same direction and you advise to just replace it, am I able to replace it by running csst in its place and tee off to the gas fireplace and then continue to the stove? Or should I run two separate lines of the csst, one to each appliance? I understand that black pipe is usually used in certain places but I will run csst since the run of black pipe would be minimal and I would rather save the unions and keep it one solid piece of pipe. Most of the run will be overhead. I’m guessing I would just need to size correctly.

 

[wwhitney]

Thank you! Since the copper pipe is run in the same direction and you advise to just replace it, am I able to replace it by running csst in its place and tee off to the gas fireplace and then continue to the stove? Or should I run two separate lines of the csst, one to each appliance?

That's entirely a sizing issue.

E.g. the sizing checks may tell you that a single run of 3/4" is enough for the section common to both appliances, or you can do separate 1/2" runs to each appliance. As a practical matter, if you need 1/2" for the branches going to each appliance, it may be cheaper to just buy one size of pipe and use parallel 1/2" runs.

[The above is just an example. Depending on your run lengths and appliance demands, you may need larger sizes. Or, less likely, you might find that a single 1/2" run is enough for both appliances.]

Of course, sizing is its own issue. You can choose between a fairly complicated exact method, or various simplified methods that will overestimate the require pipe size to some extent.

Cheers, Wayne

 

[Lefebvres090428]

That's entirely a sizing issue.

E.g. the sizing checks may tell you that a single run of 3/4" is enough for the section common to both appliances, or you can do separate 1/2" runs to each appliance. As a practical matter, if you need 1/2" for the branches going to each appliance, it may be cheaper to just buy one size of pipe and use parallel 1/2" runs.

[The above is just an example. Depending on your run lengths and appliance demands, you may need larger sizes. Or, less likely, you might find that a single 1/2" run is enough for both appliances.]

Of course, sizing is its own issue. You can choose between a fairly complicated exact method, or various simplified methods that will overestimate the require pipe size to some extent.

Cheers, Wayne

Sizing is dependent on btu of appliances, length of run, and wc of appliance as well as the wc of my supply? Is there a way to know my wc of the natural gas supply or is this standardized? I’m thinking I need to size the pipe so that the wc arriving at the appliance is within tolerances of that appliance.

 

[wwhitney]

Sizing is dependent on btu of appliances, length of run, and wc of appliance as well as the wc of my supply?

Yes, it is dependent on BTU/hr demand for each appliance, the graph of pipe types, sizes, and lengths, and the allowable pressure loss. Not sure what code is adopted in Maine, but for an example to an approach to sizing, see Section 402 of the International Fuel Gas Code.

Is there a way to know my wc of the natural gas supply or is this standardized?

I believe it's at least locally standardized by natural gas supplier and service type. The standard I'm familiar with is 0.5" wc allowable drop on a system that provides at least 7" w.c. at the meter. But there may be others.

You can measure natural gas pressure with a manometer, if you are qualified to do that work. Note that the no or low flow pressure you measure may be higher than the nominal system pressure, as the latter is I believe the pressure at the meter outlet when flowing the rated capacity of the meter. IIRC I've seen 9" w.c. at the meter under no flow conditions.

Cheers, Wayne

 

[Fitter30]

Btu input ratings of both appliances, total length of csst and size. Size of black pipe and length. Since your running the pipe and wanting to have plumber tie in appliances leak check and sign off good luck finding that plumber. Csst probably will have to electrical bonded.