Gas line advice

[John Glee]

Hi Folks,
Looking for advice regarding rerouting a gas pipe. I've got a 1" natural gas line that runs about 30' with a T to the gas water heater and up to the T with the gas furnace. At the T with the furnace it is downsized to 1/2 inch and runs about 20' to the gas fireplace (now capped).

Exactly on the other side of the fireplace is my kitchen. I would like (or have done professionally) to re-route the line through the wall for a gas cook top.

I was told the line would have to be changed to 3/4" at the furnace or I would have insufficient pressure and notice drops when the furnace kicked on. Of course this adds significantly to the job and price.

Is there a way for me to calculate this, or know if this is actually needed or not?

Could I measure the the W.C. pressure? The instructions say I need 7" supply W.C. pressure.

Thanks in advance for any and all advice.

 

[Dana]

The numbers in the grid are in 1000s of BTU/hr.

To calculate the plumbing lengths, the "equivalent length" of every tee & ell have to be added to the straight lengths:

Or, you could just measure the pressure deltas with a manometer.

 

[Sponsor]

 

[Jadnashua]

You need to find out the inlet BTU rating of the devices you want to use, add them up on that line, and then use the tables to determine if you can adequately supply that much gas. On say the furnace, if it is an older, 80% efficient, and had 100K BTU in, but 80KBTU out, you'd need to use the 100K figure. Same with the stove.

 

[hj]

The line to the fireplace will have to upsized to 3/4". The 1" to the furnace is fine.