From a VERY brief online search, a 1/2" pipe 40 feet long can pass about 81kBTU/hr worth of gas with a 1/2" water column pressure drop. You might be able to allow more drop, and get more flow, but twice the flow will result in more like 4 times the pressure drop.

Here is a link that might be useful: Example of gas sizing calculations

Here is a past GW thread on gas pipe size which might help. It also mentions the calculations attofarad generously posted.

I need to understand this topic too, so will follow along.

You might consider a cross post (XP) on the plumbing forum. I understand it's best to mention it as a XP.

Here is a link that might be useful: Past GW Thread: Gas Pipe Size - NXR or other Pro-Style Range

I will have to go back and check old posts, but it seems to me that the Blue Star required a 3/4 inch connection, so one would suspect the same for the CC.

If I can find those posts, I will put the links here, but perhaps somebody else recalls, and most likely Trevor knows?

Gary

The size of the gas line up to the range is generally recommended to be 1/4" larger than the NPT fitting. If the range has a 1/2" fitting then supply it with a 3/4" line. There's not much point buying a high output range just to starve it.

For what it's worth CSST gas line (the flexible corrugated stuff) is pretty cheap and much easier to install. Of course, it depends on how open your walls/floors are and the labor rate.

-Stooxie

Thanks everyone. The plumber def knew what he was talking about. We're going to stick to his original plan.

1" is overkill but will work so you might as well. 3/4 is a safe bet. Usually it is a question of trying to fit the larger pipe and shutoff valve in a limited space. As an example of sizing, my boiler has a 1.5" line going to it where it then reduces to 1/2 where it enters the boiler. The boiler is 175k btus.

there is a gas good practices book, with how to calculate to be sure, but the plumber was close.