Combustion air M1703.2.1

[mridgeelk]

Today I observed two 8x16 ducts supplying combustion air from outdoors for appliances totaling 402,000 BTUs. My question is that since these ducts run horizontally for about three feet before becoming vertical, should the 1/2000 for the horizontal or the 1/4000 for the vertical be used to calculate the proper sizing?

[Jim Katen]

Today I observed two 8x16 ducts supplying combustion air from outdoors for appliances totaling 402,000 BTUs. My question is that since these ducts run horizontally for about three feet before becoming vertical, should the 1/2000 for the horizontal or the 1/4000 for the vertical be used to calculate the proper sizing?

According to the language in that code section, it should be 1/2000. However, I really can't imagine why it would matter.

- Jim Katen, Oregon

[mridgeelk]

My concern was that it says horizontal or vertical, not in combination.

I may be reading to much into it, possibly caused by having two sons and a daughter-in-law that are lawyers. They even find meaning in the spaces beween the words.

Today I observed two 8x16 ducts supplying combustion air from outdoors for appliances totaling 402,000 BTUs. My question is that since these ducts run horizontally for about three feet before becoming vertical, should the 1/2000 for the horizontal or the 1/4000 for the vertical be used to calculate the proper sizing?

According to the language in that code section, it should be 1/2000. However, I really can't imagine why it would matter.

- Jim Katen, Oregon

[Jim Katen]

My concern was that it says horizontal or vertical, not in combination.

I may be reading to much into it, possibly caused by having two sons and a daughter-in-law that are lawyers. They even find meaning in the spaces beween the words. . .

But it doesn't say horizontal or vertical. It says, "Where horizontal ducts are used . . ."

Since the scenario you described uses horizontal ducts, that's the part you follow.

- Jim Katen, Oregon

[mridgeelk]

Thanks, Jim

My concern was that it says horizontal or vertical, not in combination.

I may be reading to much into it, possibly caused by having two sons and a daughter-in-law that are lawyers. They even find meaning in the spaces beween the words. . .

But it doesn't say horizontal or vertical. It says, "Where horizontal ducts are used . . ."

Since the scenario you described uses horizontal ducts, that's the part you follow.

- Jim Katen, Oregon