Heat N Glo DVP Adapter?

Hello all. This is my first time post, and I am hoping to get some help from this site with my current situation:

8 years ago we built our house with an unfinished basement. On the main level, we installed a Heat N Glo Northstar for our primary heat. I knew that someday we would like a gas fireplace in the basement, so we had our builder stub a b-vent into the basement along side the woodburner chimney for future.

The time to finish my basement is now, and I ordered an Empire 42" Premium B-vent fireplace, 30K BTUH for the basement. After the fireplace arrived, I hopped up on a ladder to start measurements for the B-vent connection and noticed that the B-vent is not what I typically see at the DIY stores. I am learning that what I have is likely the HnG DVP pipe, which is proprietary.

The Empire fireplace has a 6" connection, and the existing HnG DVP stubbed down into my basement is around 5-3/4" for the inside pipe. Is there an adapter available that I can use for making the connection from the Empire to the DVP, or am i looking at replacing my entire B-vent from the basement to the chimney termination?

Please help if you know something about this. I hope I didn't make an expensive mistake assuming that B-vent was universal.

Thanks in advance for all responses.

Jeff

+1
so you want to connect the 6" empire to the 5.75" inner linning of the DVP pipe?

might be physically possible, but certainly not to code, and could pose performance and safety issues.