I currently have an electric range but want to convert to gas. The main going into my house is a 1" line. There are 1/2" branches for the water heater, dryer and furnace. There is a T that has a 1/2" port plugged off the 1" line. It is about a 12' run from the T to where the stove connection would be. The stove is approximately 60k btu. Based on the charts and what I read I should be fine with 1/2" pipe but want to get others thoughts. I know a lot of people recommend 3/4" for a range but want to get others thoughts. I'd rather not to have to disassemble everything that is already there.

 

So the most obvious, have you confirmed with the manufacture?

 

The manufacturers don't specify gas piping size.
Ranges have 1/2" connections but that doesn't necessarily mean that a 1/2" line is sufficient.

How long is the 1" pipe ?
The furnace, the dryer and the tee are all directly off the 1" line ?

I think the 1" line is large enough to carry all the consumption.
You have 12' , probably a fitting or two, a valve and a flex line.
20' of 1/2" line yields 75kbtu's. You should be ok with 1/2".

 

To tack onto Pete's response, what's the BTU capacity of your furnace? 1" is usually the minimum run to most furnaces due to volume requirements and might be tight.

 

Some more information. The house is a side x side duplex and the line travels through my neighbors basement (can't be 100% sure what size pipe passes through his unit to mine but it would be about 30' long. When it enters my unit it splits into 2 - 1" pipe. One section branches off to the hot water heater and then upstairs to the dryer. The other 1" pipe runs about 16' to the furnace and T's off with a 1/2" line going to the furnace and the other side capped. The furnace is a Heil HE 100,000BTU furnace.