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# 411 BTUs through 1" CSST pipe?

#1
09-17-13, 10:14 AM
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Join Date: Sep 2007
Location: New York
Posts: 22
411 BTUs through 1" CSST pipe?

My HVAC guy is installing a new CSST gas line for me. Based on my calculations, the total of all the gas appliances is 411.5 BTUs.

I've calculated the total length of the longest leg to be 70 feet (to the most distant appliance)

He's planning on running a short length of 1" CSST pipe from the meter to the gas manifold (~5 feet), then individual CSST lines to each appliance.

I expressed my concern to the HVAC guy, but he told me that a 1" pipe can handle that amount of gas when the length is short. But, I thought you based the capacity of the pipe on the total length of the longest leg.

Is CSST somehow different? Does the manifold change things (all should be open)?

Am I right to be concerned that a 1" pipe can't handle that amount of gas?

As a test, I plan to turn all the appliances on at the same time and see if anything chokes/stalls/flames out (gonna get warm for a while).

#2
09-17-13, 10:29 AM
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Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,799
Based on my calculations, the total of all the gas appliances is 411.5 BTUs.
I've calculated the total length of the longest leg to be 70 feet (to the most distant appliance)

He's planning on running a short length of 1" CSST pipe from the meter to the gas manifold (~5 feet), then individual CSST lines to each appliance.
No, not as far as I know.... The rule is from the code books is once in the ft column you must stay in that column. Based on your 70 ft you must use that column from the chart. 1" will only support 240K BTU...

According to the chart you must use 1 1/4" . That supports 490k btu

Am I right to be concerned that a 1" pipe can't handle that amount of gas?
I would be.. Have him show you in the code where it says use of manifolds changes anything.

As a test, I plan to turn all the appliances on at the same time and see if anything chokes/stalls/flames out (gonna get warm for a while).
Is it piped? Why would you let him pipe it if its wrong???

My HVAC guy is installing a new CSST gas line for me.
There may be your issue. He most likely is not a licenced plumber and working under someones license... Get a signed document from the plumber he is working under that this is OK. I doubt they will produce it.

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