Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

Aaron Fude wrote:
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

Why not just run the duct above the joists out to the wall? Or straight
up through the roof? Or is this installation not on the uppermost
floor? If the latter, how about a wall mounted exhaust fan?

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On Nov 28, 7:26 pm, Aaron Fude wrote:
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

I'm going from memory here......holes in joists.

Never in the center 1/3 of the span, no notches

Must allow 2" min (1/3 of the joist depth?) between edge of hole & top
or bottom of joist

If these "rules" are correct that means about a 2.5" hole max in a
2x8... ~3" hole in a 2x10

Of course you could make aluminum (or steel) doubler plates to
reinforce the holes in the joists

but in any case a 6" hole is pretty big you could go rectangular
duct to minimize hole depth (like a 3 x10) might work. out ok but I'd
still consider the doubler plates.

cheers
Bob

"Aaron Fude" wrote in message
...
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?


Run the exhaust between the joists to the closest compatable wall. Use a fan
compatable with a 3 or 4" duct otherwise, and reinforce the joists.

On Nov 29, 12:26 am, Aaron Fude wrote:
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

Look for another contactor

"Aaron Fude" wrote in message
...
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?


You should be able to find larger CFM fans that only use 4" duct. I don't
think gouging out a good portion of your joists is a good idea. Another
possibility is to build a small soffit to accommodate the duct.

NO!

If the contractor is a licensed "professional", he MUST be right and the homeowner MUST be wrong and is an idiot.

Just ask anyone on alt.hvac.

;^)

Eric Law

PS To the original poster, I actually agree with Robson - what your contractor is suggesting is a really *bad* idea. Only
way I can see 6" holes in joists making sense is if they're very large engineered lumber and documentation is in hand stating
a hole that large is okay.

wrote in message ...
On Nov 29, 12:26 am, Aaron Fude wrote:
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

Look for another contactor

At the risk of sounding silly, is there *no* way to run the duct between the joists rather than
across them?

Even if it's a considerably longer run, it would be better than having the floor collapse ;^)

Eric Law


"Aaron Fude" wrote in message
...
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

According to John Grabowski :

"Aaron Fude" wrote in message
...

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

You should be able to find larger CFM fans that only use 4" duct. I don't
think gouging out a good portion of your joists is a good idea. Another
possibility is to build a small soffit to accommodate the duct.

Or install more than one exhaust unit so you can use smaller venting.

6" seems rather extreme. IIRC, our main bathroom (9x18) could be
vented properly with one high CFM (220CFM I think) fan with 4" duct
or two fans with 3".

Another possibility is to use multiple inlets with a blower mounted
elsewhere. You could use smaller inlets (within reason) without paying
the noise penalty if the blower is installed elsewhere.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

"Aaron Fude" wrote in message
...
Hi,

How does one install an exhast fan when the joists run parallel to the
outside wall. My prospective contractor recommends drilling holes in
the joists. This is a larger bathroom so I need a larger fan so I am
going to have 6" holes in my joints. Isn't that effectively cutting
them in half? What could be an alternative solution?

Thanks!

Aaron

Depending on the duct run, you can get good service from a smaller duct and
use a good quality fan that can reduce to a 3 or 4 inch duct. I did the
same thing in a weekend place, and have a 90 CFM Panasonic unit there that
works great. It reduces to a 4" duct.

I cut an "oval" type notch in the joists impacted (accessed by lifting a
section of upstairs floor) and used a flexible duct to allow it to gently
change from round to oval where it crossed the joists. That way I only
needed to cut 3" vertical in the duct, which did not greatly impair the
load-bearing ability. The metal reinforcement is a good idea that I would
have used if I was any closer to the center of the joist span.

Anyways, it worked great for me. It's about a 5 foot run, and very strong
exhaust at the outside wall.

p.s. No way I'd drill 6" holes in any joists...

Well, here's the fan that I like:

http://www.westsidewholesale.com/ind...&CATEGORY=6343

Not that I need 150 CFM as my bathroom is only 7'x8' but I'm attracted
to its very low sones. Or are sones largely bs?

On Nov 29, 4:17 pm, Aaron Fude wrote:
Well, here's the fan that I like:

http://www.westsidewholesale.com/ind...=@@@@117373680...

Not that I need 150 CFM as my bathroom is only 7'x8' but I'm attracted
to its very low sones. Or are sones largely bs?

Panasonic are good fans. The noise thing is very much a personal
issue. Some people don't mind a louder fan as it provides masking
sounds and it _sounds_ like it's working! Totally your call.

Someone touched on the remote blower - if you have another bathroom
you could get a larger blower and run both ducts to it, then a duct to
outside. That may let you run the ducting in a better way. Only
thing with those multi-zone exhaust fans is that both rooms will have
air exhausted when either bathroom switch is turned on. There are
damper registers that are automatic. It's not a cheap way to go in
any sense of the word.

R

"Aaron Fude" wrote in message
...
Well, here's the fan that I like:


http://www.westsidewholesale.com/ind...&CATEGORY=6343

Not that I need 150 CFM as my bathroom is only 7'x8' but I'm attracted
to its very low sones. Or are sones largely bs?



According to this calculator you don't require that many
CFM's:http://lib.store.yahoo.net/lib/rewil...alculator.html

The Panasonic fans are great. My customers love how quiet they are. Use an
80 CFM unit and you will hardly know that it's on. For good ventilation an
exhaust fan requires makeup air. If you have forced air heating, connect a
small duct to the return line and run it outside. Of course you can always
open a window somewhere.

You may find better prices he http://www.rewci.com/

"Aaron Fude" wrote in message
...
Well, here's the fan that I like:

http://www.westsidewholesale.com/ind...&CATEGORY=6343

Not that I need 150 CFM as my bathroom is only 7'x8' but I'm attracted
to its very low sones. Or are sones largely bs?

Not BS at all. We have a fairly nice townhouse that was built well in most
respects. It is recent construction, done well, and the finishings were
several grades above the standard tract level. The master bath is large
with slate floors and granite counters. Along with this nice facade was a
crappy contractor grade Nutone ceiling fan. It didn't work well, sounded
like a Lear Jet winding up, and was a pain from the start. It always
annoys me to see the hidden junk that [some] contractors will use to save a
few bucks in an application like this.

Finally last year I replaced it with a 50CFM Panasonic unit (baby brother of
the one the OP linked to). When I first turned it on, I thought I had wired
it wrong, since I couldn't hear it at first.

We went with the 90CFM (or was it 80?) unit at our tiny cabin for two
reasons. First the celing is low so it needs to be cleared of steam faster
when showering, and secondly because the bathroom is right off the kitchen,
and some privacy is a nice touch. Still the sound generated is very low
compared to low grade offereings.

Go to a good supply place and see if they have demo units set up. Turn them
on and hear/feel the difference. It really is quite an eye-opener.

On Nov 29, 5:49 pm, "John Grabowski" wrote:
"Aaron Fude" wrote in message

Not that I need 150 CFM as my bathroom is only 7'x8' but I'm attracted
to its very low sones. Or are sones largely bs?

According to this calculator you don't require that many
CFM's:http://lib.store.yahoo.net/lib/rewil...alculator.html

There's more to figuring out the required air flow than the size of
the bathroom. A whirlpool tub can require a much larger size fan than
that calculator indicates. From that same web site:
"Click Here For R.E. Williams Bathroom Fan Calculator (The result
represents the minimum recommended cfm rating for your bathroom fan).
You can view this link for a simplfied explanation of the
recommendations of the Home Ventilating Institute for bathroom
ventilation - Bathroom Ventilation Recommendations.
Click Here For A More Technical method using a chart to properly size
a bathroom fan. Remember, if you have a steam room, sauna, or hot tub,
you will need to increase the size of the fan to compensate for
additional moisture. "

The Panasonic fans are great. My customers love how quiet they are. Use an
80 CFM unit and you will hardly know that it's on. For good ventilation an
exhaust fan requires makeup air. If you have forced air heating, connect a
small duct to the return line and run it outside. Of course you can always
open a window somewhere.

Why add makeup air at all? Most houses aren't nearly that tight, and
ones that are that tight probably already have an air-to-air heat
exchanger (aka HRV). I can't see how opening a window helps at all.
It'd be a net energy loss amongst other things. And that's pretty
much what that Williams web site indicates:
http://lib.store.yahoo.net/lib/rewil...ntilation.html

I agree that the 150 CFM is overkill for the OP, and that 80 or 100
CFM would do the job nicely and that the Panasonic fans are good
products.

R