the manufacturer of the brand we use says in their
instructions don't put ANY screws into their nice shiny metal B-vent.
Obviously, this makes supporting the flues a bit trickier.
An old-timer in our outfit says the mfg is just covering
their butts...that if one uses short enough screws to
NEVER pierce the liner a few screws are ok. He claims, beyond
the obvious problem of a hole being a potential flue gas leak, that
when a too-long screw is in contact with both the liner and the
outer shell it sets up galvanic corrosion and the liner
can erode pretty quickly into powder.
Thoughts, anyone? How do you'uns support flues when they can't go straight up?