Direct Vent Boiler Into A Standard Flue?

I have an oppurtunity to pick up a new Peerless Direct Vent oil fired boiler for a song. I would like to use it to replace my 20 year old Peerless boiler which has given me good service but is showing its age. My question is can I duct the exhaust into the standard 8 inch flue that my old boiler now uses ? Any replies will be appreciated, thanks.

Probably not. These units are designed to operate at a very specific draft.

You need to get the specific installation instructions for that unit, but unlikely that they would allow a direct vent into a vertical flue.