I used table A.2 for Schedule 40 gas piping and Table A.9 for copper tubing in the example below. (7-14" wc @ 1" wc pressure drop). For 2 psig use Tables A.3 and A.10.

In this given example let's use,

E = Furnace (60,000 Btu)

F = Fireplace (25,000 Btu)

G = Pool Heater (150,000 Btu)

H = Water Heater (40, 000 Btu)

First determine the farthest distance in your gas piping system. In this example it's section A to E = 50'. Then determine the total Btu's of the system = 275,000 Btu.

**When using the gas piping tables, the trick is to ONLY use the farthest distance when sizing regardless of the length. In this example it's the 50' line.** Section A to B is the first section of gas piping before any appliance branch line is installed. Section A to B needs to have enough capacity to supply our entire system. Using the 50' line in Table A.2, we need to use 1" gas piping, which has a capacity of 374,000 Btu. This is sufficient to supply our appliance total of 275,000 Btu.

Section B to C would need to supply our total Btu less the 40,000 Btu water heater = 235,000 Btu. Using the 50' line, we would need to use 1" gas piping.

Section C to D would need to supply our remaining total Btu less the 150,000 Btu pool heater = 85,000 Btu. Using the 50' line, we would need to use 1/2" gas piping, which has a capacity of 95,000 Btu.

Section B to H would need to supply the 40,000 Btu water heater. Using the 50' line, we would need to use 1/2" gas piping. If we installed copper tubing, using Table A.9 @ 50' we would need to use 5/8" tubing.

Section C to G would need to supply the 150,000 Btu pool heater. Using the 50' line, we would need to use 3/4" gas piping, which has a capacity of 199,000 Btu.

Section D to F would need to supply the 25,000 Btu fireplace. Using the 50' line, we would need to use 1/2" gas piping. If we installed copper tubing, using Table A.9 @ 50' we would need to use 1/2" tubing.

Section D to E would need to supply the 60,000 Btu furnace. Using the 50' line, we would need to use 1/2" gas piping. If we installed copper tubing, using Table A.9 @ 50' we would need to use 5/8" tubing.