A handy friend of mine said that I could convert the round pipe to a rectangle (3 x 10) that could run through the drywall. However, the heating contractors I've spoken with on the phone are saying I can't do this and I need a new furnace and hot water heater to direct-vent the air out.
My concern is that these heating contractors are mostly trying to sell a product rather than really telling me what I could do more economically. I'm also concerned that if I follow my friend's advice, I might not be up to code (and could potentially endanger my family...).
I'm not very handy and would appreciate any advice.