Is there a fan that fits in the vent of an a/c (or forced-air heating)
duct? My home has forced air & central A/C. We have a basement plus two
stories and attic (attached townhouse). The a/c does not come out strongly
enough on the top floor...sometimes not that great on the first floor.

We DO have enough BTUs, apparently--we paid for extra--(I could check
the footage etc but it may not be relevant to this general
question)--and an expert just said the contractor probably didn't
supply any extra ducts, so the extra BTUs are not doing enough.

One possible solution -- I think? -- is to put fans in the ducts. I
assume this would be done in the basement, where access would be
easier, and I assume the air can be "pushed" up two floors(?).
stories. However, it also occurred to me that if there was a product
involving a vent with a fan built in, I could just replace my current
vents with these, with no installation expense.

Does such a vent/fan product exist? I've searched on the internet of
course, haven't found it. In any case, would that do the trick? It
would be "pulling" air throught the duct, which might not work as well
as pushing it...

...which leads back to the other question: Would installing fans in
the ducts down down in the basement work, and how costly might that
be?

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Request for Question Clarification by pafalafa-ga on 06 Jul 2003 14:11 PDT

Hello bbb-ga,

A while back, I remember seeing just such a device, known as a duct
fan, in our local harware outlet, and considering it for the house. 
The clerk at the store said they are very effective in selectively
increasing air flow and adjusting temperature on an as-needed basis.

Here are some links to sites that sell duct fans (sometimes called
booster fans as well) and have other info as well:

http://www.smarthome.com/3011.html

http://www.espenergy.com/in_line_duct_fan.htm


http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?CNTTYPE=PROD_META&CNTKEY=misc%2fsearchResults.jsp&BV_SessionID=@@@@1486115796.1057525650@@@@&BV_EngineID=ccehadcikhlefjicgelceffdfgidgnj.0&MID=9876&frmSearchStr=duct%20fan


Beyond those links, you seem to be looking for other information, but
I'm not 100% clear what you're after.  Do you want studies of the
effectiveness of the duct fans?  User testimonials?

Let me know what info I can add here to be able to provide you a
complete answer to your question.

Thanks....and stay cool.

pafalafa-ga

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Clarification of Question by bbb-ga on 06 Jul 2003 15:16 PDT

to pafalafa-ga:
Thanks for responding. I did know about the existence of those duct
fans, but my questions are still these (they were actually part of my
original question):

1. I assume it's cheaper and faster to install duct fans in a
basement, where the ducts are complely accessible. But would they be
effective there? Or is it necessary -- or much more effective -- to
install them "higher up" and closer to the vent? Cutting into the
ducts higher up means cutting the wall, replacing the drywall, and
then of course repainting, I guess.

2. Are there fans that are not duct fans but VENT fans? That is, are
there fans that can be installed at the vent -- or are part of a vent,
in effect -- so they can be put in simply by replacing a vent? This
would seem much cheaper and easier. Does it work, and do they exist?

Studies of the effectiveness, etc., would be good, but first I'd just
like to know

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Clarification of Question by bbb-ga on 06 Jul 2003 15:18 PDT

...if vent fans exist.

(I somehow cut off or omitted the last 4 words of that clarification.)

This is a common complaint in many new houses.
If your wallet is lucky, the fan speed was set (wired) on medium, not
high by the installer.  Changing it to high could solve your problem.
( You might want the installer to provide a switch between medium &
high for winter/summer.
The second but more expensive alternative is to have a good A/C tech
check return air flow CFM.  Often times a duct improvement on the
return air side will solve the problem you describe.

robertw-ga is right, this is a common complaint that is often solved
by looking not at the distribution system, but how much return air can
get to the A/C unit.  You can try removing the grate to see if that
improves airflow.

But to your original question, there are "register fans" that fit into
the register, as well as fans that fit into the duct work.  See
http://www.fieldcontrols.com/reg.booster.shtml for an example of a
"register fan" that is around $50.  I suspect that having a cord run
down a wall, if the register is mounted high on the wall, will be
unsightly.

When you get to that site, notice the links below the graphic that
runs along the top of the page.  Allow your mouse to hover over "Air
Booster" and you'll get a menu to several articles Field Controls has
on the products it sells.  Their FAQ on "Air Boosters" is at
http://www.fieldcontrols.com/faq.html#anchor1247813

To robertw and fshagan:

Many thanks! You've both provided very useful help, with fshagan
responding directly to the question -- and robertw raising a point I
hadn't thought of, but which also might provide a solution. Or both
solutions together might be best...(I realize I neglected to respond
to robertw until now; I think I deleted the e-mail from Google about
that comment, before reading it.)

Actually, either comment can qualify as an answer, especially the one
about the register fan... Wish Google had allowed a split-fee
arrangement; I'm not sure how to deal with this.