Can I Use 6" Flue on EFM 520?

I'm thinking of buying a df 520, which recommends an 8" flue. I have 6" round steel flue pipe. Can it be done?

Yes it can be done. I used 6" for several years until I got the chimney built. It doesn't work good if you are going to use it on higher settings. I used mine on 4 and 5 teeth feed with the same air and didn't have issues until I jacked it up to 6 and above air. You can also get a little help with a draft inducer like several other members are successfully running.

I know it's done. But if you run into a fire code inspector, he will only allow 7" (or larger). It pertains to the BTUH output of your unit, not how well it works in your personal setup.

Thanks for your input - much appreciated!