Jags said:
You will have to stay with the same brand if you need additional parts/length. No - its not required to have insulation. It becomes less of an issue if the chimney is internal to the building v.s. an external. There are other "pour in" types of insulation available as well. Insulating the liner is highly recommended (by me anyhow) when lining an external chimney, and if possible, even an internal one.
Jags, I have to disagree with the assertion that insulation becomes less of an issue for an internal chimney. Your statement is true from a performance perspective, but from a safety or code perspective, insulation is very likely more of an issue when relining an internal masonary chimney, except in rare cases.
I wrote a post called
"Why you probably DO need an insulated liner" a few weeks back. The basic point is that, if code is an issue for the owner, it is rare that an internal chimney will meet code when relined without insulating. It likely didn't meet code when it was built in the first place. Outside of the code discussion, from a safety point, an insulated liner is just safer, especially in a chimney fire.
So for the OP, I say you probably DO need to insulate your liner. Give my post a read for the details.