Tom wrote:
It somehow sounds like your sales guy should stick to sales. It
sounds like he is worried about the fact that the exhaust is going
up as opposed to over. I have heard that one before, but given the
the exhaust is warm, it naturally rises and you could need less, not
more effort to exhaust out the roof straight up than the same total
distance in any other direction, especially if other directions
required bends.

True, the warm air will rise, but it won't have enough force to take
the lint with it. Only about 70% of the dryer air goes through the
lint filter. The rest is allowed to bypass the filter...I assume to
prevent problems if the filter is full. This air carries lint with
it and will quickly clog the vent line if the line is too long or too
high in the air.

I agree that too long is bad, lint or no lint. I really don't see how
longer is worse for lint, other that it means more to keep clean. I really
don't see how high has anything in this. Assuming the total length is not
too long and there are not too many bends, up or over is the same concerning
lint. In fact up might be even easier to clean if it were to fall back down
so you could clean it out at the first bend; but of course it does not, you
still need to clean them.

The suggestion of a booster fan in the line would
probably help.

I have one on mine since the total distance and minimum number of bends
is beyond that specified by the manufacturer.

I might also add here that the specs for duct length is based on solid
metal pipe, not that corrugated junk or worse yet the flexible plastic
stuff.

I sold dryers in AZ where it is common to run
straight up through the roof and I postponed the replacement of many
dryers by telling the customer to simple clean out his vent line. It
would usually be plugged right where it made it's first turn up into
the wall. The worse was of course when the builder put another 90
degree bend in the ceiling to go horizontally out a side wall. Really hard
to clean that out.

I agree. I have to disassemble part of my line in the basement for
cleaning. And you are right, I would expect most of the lint to be at the
bends. It is a shame that most people don't know they need to service these
things. Maybe even worst that they don't know enough at the time of
installation to consider the problems of maintaining them at that time.

Tom.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math