Biasi boiler vent/supply air question

Help me folks… this is one of the first Biasi boilers (Italy) I have seen during an inspection… not sure if I am seeing things right here…

the supply air to the burner appears to be drawn in from the exhaust vent? Is this correct? I could not imagine so but… hey been wrong before… sorry but I did not seem to get a good photo of the supply air feed at the burner.

Please correct me if my thoughts this is an incorrect set up are wrong!!!



Is that a direct vent type pipe? Does it exhaust out the center of the pipe and draw combustion air from around the perimeter of the pipe?

Hi Jeff,

I believe that it is a double wall exhaust vent, where the cold intake air is in the outside air space and the hot air exhaust is vented outside on the interior center of the pipe. Rinnai space heaters are vented this way also.

hope this helps


Looks like it combination intake-exhaust vent.

See this product sheet pdf.

directventfinal.pdf (199 KB)

More info in manual is available here:

thanks guys… I had read about the double wall vent… but never seen them so was taken back by the set up… I told the buyer it may be such a set up but would look into it more… thanks for the education…

Thanks michael… I was on that page as you posted sifting throught the manual… you guys are on top of it tonight!

If you have a picture of the flue from the outside please post it.:slight_smile: