"Goedjn" wrote in message
...
I'm contemplating tearing down my chimney and putting in a
zero-clearance stainless stovepipe for my oil-furnace instead;

All the stove/chimney/other flue systems I've ever seen have
the pipe from the appliance go up, turn horizontal, and plug
sideways into the chimney stack. Is there any reason
why I shouldn't go straight up from the oil-furnace, through
the roof? It's pretty much open all around.

--Goedjn


Depends.
The International Mechanical Code, what most areas in the US are using will
still require a particular height above pitch for your furnace exhaust. You
may find that that bright stainless pipe sticking so far up on the roof will
be far worse looking than a chimney.

If you do it, check the local codes first. Read Mechanical Code section
804.3.5
BTW, drip legs are not to code, as section 5, of 804.3.5 clearly states. and
this will also add an additional 15 to20 feet total effective length (TEL)
to your exhaust, and as each make of furnace has a total length, you may
find that you have exceeded this with a so called drip leg.

Since you have what is called a forced draft system (oil) you will also have
to insure that each joint is sealed properly. Code section 804.3.1

And I hate to look like I am busting on everyone that has replied so far,
but Mark is wrong about the draft. Oil units are forced draft, therefore
draw isnt an issue since the exhaust will be a positive pressure style.

If you dont mind, why are you considering this? I mean....most people do not
want a mobile home style roof jack on their home.