Currently, I have an older gas furnace and gas hot water heater that
common flue vent. The vent is a 6" diameter pipe and runs from
roof. I am considering installing a 95% efficient furnace.
I've been told that
if I switch to direct vent on the furnace and
'orphan' the hot water heater vent
that the current flue will be too
big and I'll have condensation problems in the
It sounds like I can either install a stainless steel liner which won't
effected by condensation, or install a smaller flue pipe which will
velocity/pressure of the gas and it will be OK.
Can I do either of these myself? What about the flexible aluminum
vents, can I
just pull one of these through the existing pipe?
By the way, I'm having the furnace installed by pros. They said I
don't need one, though another company/quote said I did. Just
wondering if I
have trouble down the road how easy it will be to fix.