We have a new deck that attaches to the house and extends 18' outward.
To eliminate the moist exhaust from discharging under the deck we used
4" galvanized stove pipe coming from the inside of the ledge board on
the house all the way through the outside of the deck structure. We
fit a flapping louver on the outside flush with the deck fascia board.
While this seems to work just fine, it seems our drying time has
increased somewhat. Most likely this is due to the extended distance
the air must be "pushed" to exhaust to the outside. Prior to
installing this I checked the dryer manufacturer's site to calculate
the maximum length of the exhaust and our total was well within the
So, my question is this: Has anyone every installed an auxilliary
exhaust fan on the outer end of a dryer vent before? Does anyone know
of a cylindrical fan that might fit into a 4" pipe? What would be
ideal is a section of exhaust pipe containg a fan that could be retro
fit on the end of this setup.
Anyone have any suggestions? Thanks for any ideas.
Thanks guys. You have given me hope that my idea is NOT crazy. One
of the suggestions shows a booster fan that can be mounted in the
cellar BEFORE the vent exits to the outside long run. Also, the boat
bilge blower is a good suggestion as well.
Thanks again for the great input.
It is possible that the vent pipe is clogged with excessive lint. I suggest
a cleaning. Also, the vent pipe is long enough and extends outside that the
warm moist air from the dryer will likely condense inside of the pipe. That
moisture will cause lint to get caught easily in the duct accelerating the
clogging process. I suggest that you insulate the entire length of duct
with duct wrap to stop the condensation.
There are several 'booster' fans available for dryer vents,
but they're pretty pricey and add one more potential problem
to the system. I've never tried one, but if your vent duct is
all smoothwall, an annual checkup and cleaning would probably
be a lot less hassle and long term expense than a booster,
IMHO. As long as you're still within the max recommended
length, I wouldn't be too concerned if you clean it regularly,
even though drying times will naturally increase a bit.
And you can do a pretty good job of cleaning with a 30'
central vac hose and shopvac, working from the outside with
the dryer running on 'no heat/fluff'. They also make 4" brushes
for the job, though I've never had a need to use one (and
have heard horror stories from fellow servicers about the
brushes coming loose from their long flexible poles *inside*
a long vent run! Yikes!)
These boosters can be purchased with a pressure switch that
automatically starts them when the dryer runs. They cost around
You can see a couple of these in the current Armstrong parts
catalog (wholesale only) here:
From this page, click 'online parts catalog', then enter 32 in
the 'page jump' search box. The one at the bottom of the page
is an isolated motor design, which means lint won't get to the
motor (still can clog the fan blades, though).
Hope that's of help to you.
Dave's Repair Service
New Albany, PA
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If you're a little savvy with the electrons you may want to give some
thought to using a bilge blower. They make them to fit a 4" tube,
already have mounting brackets attached, and are designed not to light
off fuel vapors, so I'd think they'd be fine around the lint as far as
combustion goes. Plus they're only ~$25 (West Marine). Unfortunately,
most boats run on a 12V or 24V DC electrical system, but a xformer could
Just my $.02
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