If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

On 03/08/2014 03:05 PM, DerbyDad03 wrote:
If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Noisier? More drafty? It will get rid of the stink faster, but if you
are leaving it on for 20 minutes, for instance after a shower, while
there is still water on surfaces, it will pull more air through the
house, so you will use more A/C in the summer and more heat in the winter.

Practically, though, I don't think the specs on bathroom fans are all
that tightly regulated, and they are both in the same ballpark, anyway.

Jon

On 3/8/2014 5:05 PM, DerbyDad03 wrote:
If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?


For a bathroom one has to consider that while the unit is on the door
will most likely be closed. What air flow will the door allow
a 110 vs 80 CFM and will that number be sufficient to eliminate
moisture (primary purpose) at the rate you desire.

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.

On Sat, 08 Mar 2014 19:50:44 -0500, Ed Pawlowski wrote:

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.
I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Sure a bathroom fan can be too big. See those tornado pictures where
the house is flying away, or the Wizard of Oz. All of that because
the bathroom fans are too big.

Rural people who have never had a bathroom fan before get carried away
and buy a model much too big.

On Sat, 08 Mar 2014 20:35:19 -0500, wrote:

On Sat, 08 Mar 2014 19:50:44 -0500, Ed Pawlowski wrote:

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.

I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)

I thought bathroom fans were only required, and maybe only installed,
when there was no window. This the first place I've ever lived without
a window in the bathroom, and I don't like it.

Not at all.

In fact, when I was replacing bathroom ceiling fans in my building, I went with the NuTone 8832 fan because it was the largest CFM fan I could get from NuTone without having to pay extra for their quieting technology or go to a 4 inch diameter duct.

All of my existing ceiling fans were 3 inch ducts, and so I figured I'd go with the largest CFM 3" duct fan that I didn't have to pay extra for features I really didn't need.

I tell my tenants that after a shower or bath, to operate their bathroom fans with the bathroom door CLOSED. The reason for that is that it forces the majority of the make-up air to come in under the door, and that promotes gravity segregation of the colder and hence denser make-up air at the bottom of the room and the warmer lighter moisture laden air on top, and that promotes better sweep efficiency of the bathroom. If you leave the bathroom door open, dry air is just going to get sucked in at the point closest to the fan, and that'll be at the top of the open door, so most of the volume of warm moist air in the bathroom won't be displaced. Just make sure you have a good 1/2 inch of space under your bathroom door.

On 3/8/2014 8:35 PM, wrote:

I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)


The problem is getting all members of the household to do it. Leave the
door cracked open an inch too.

Ed Pawlowski wrote:
On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.

The best for noise is having the fan out of the room. I have one in the
attic.

Greg

On Sat, 08 Mar 2014 22:06:45 -0500, Ed Pawlowski wrote:

On 3/8/2014 8:35 PM, wrote:

I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)


The problem is getting all members of the household to do it. Leave the
door cracked open an inch too.
With no humidifier in the house, just cracking the door also works
and helps get the humidity in the house up over 15%

wrote:
On Sat, 08 Mar 2014 19:50:44 -0500, Ed Pawlowski wrote:

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.
I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)

Panasonic was the plan.

I want to replace the current fan with a fan heater combo. I will be
running a dedicated 20A circuit.

micky wrote:
On Sat, 08 Mar 2014 20:35:19 -0500, wrote:

On Sat, 08 Mar 2014 19:50:44 -0500, Ed Pawlowski wrote:

On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03
wrote:

If the calculations for a bathroom exhaust fan (cubic feet + equivalent
duct length) indicate an 80 CFM fan, is there any issue with using a 110
CFM fan?

Only problem is it will suck out more heat from your house, but it
will also get rid of the stink or excess moisture from the shower
faster. I have an 80 CFM and it works for us.

Be sure to get a quiet one. Panasonic has some of the best for noise.

I just crack the window an inch before jumping in the shower and
there is NO humidity problem (particularly when it's -23c outside)

I thought bathroom fans were only required, and maybe only installed,
when there was no window. This the first place I've ever lived without
a window in the bathroom, and I don't like it.

They may be required if there is no window, but they are certainly
_installed_ in many bathrooms that have windows.

I have a fan now but SWMBO wants a heater also, so I'm replacing it. Yes, I
will be running a dedicated 20A circuit.

On Sunday, March 9, 2014 9:58:06 AM UTC-4, DerbyDad03 wrote:
micky wrote:

On Sat, 08 Mar 2014 20:35:19 -0500, wrote:



On Sat, 08 Mar 2014 19:50:44 -0500, Ed Pawlowski wrote:



On Sat, 8 Mar 2014 23:05:34 +0000 (UTC), DerbyDad03

wrote:



If the calculations for a bathroom exhaust fan (cubic feet + equivalent

duct length) indicate an 80 CFM fan, is there any issue with using a 110

CFM fan?



Only problem is it will suck out more heat from your house, but it

will also get rid of the stink or excess moisture from the shower

faster. I have an 80 CFM and it works for us.



Be sure to get a quiet one. Panasonic has some of the best for noise.



I just crack the window an inch before jumping in the shower and

there is NO humidity problem (particularly when it's -23c outside)



I thought bathroom fans were only required, and maybe only installed,

when there was no window. This the first place I've ever lived without

a window in the bathroom, and I don't like it.



They may be required if there is no window, but they are certainly

_installed_ in many bathrooms that have windows.



I have a fan now but SWMBO wants a heater also, so I'm replacing it. Yes, I

will be running a dedicated 20A circuit.

Certainly all the bathrooms around these parts (NJ) that I've seen
that have been built in the last 30+ years have fans in the
bathrooms whether they have windows or not.

I don't see any problem with going with the larger fan.
It's not like you are making it 5X or something. And as I'm
sure you already know, you definitely want to spend a little
more for a quiet one. They have displays at HD or Lowes as
I recall where you can hear the difference. It's sad too what
builders get away with. Here they are building $1mil homes with
the cheapest, noisest crap fans. They probably cost about $35.
For $50 you can get one that makes half the noise and
for $70 one that is super quiet. So, they cut cost on that whole
house, 4 fans, by $60 to $140 and the owner winds up with crap.

For things that are more personal preference and easy to
change, eg light fixtures, I don't have such a beef with.
But a noisy bathroom fan isn't easy to fix. In most cases,
you have to rip the ceiling open to replace it. I have recently
seen an upgrade kit in one of the stores that fits some models,
where you can retrofit it, but I suspect that only fits a
small segment of the problem ones. And I don't even understand
why the builder thinks this makes sense for them. I'd put in
the better fan and then feature that as a selling point, show
them that as an example of why you're house is better, etc.
There are a bunch of similar things like that a builder could
do that I think buyers would appreciate and it would help them
sell the house and at a better price.

I have often wondered why bathrooms with fans dont have a air vent, perhaps in the door to allow air flow when the fan is on?

On 03/09/2014 06:22 PM, bob haller wrote:
I have often wondered why bathrooms with fans dont have a air vent, perhaps in the door to allow air flow when the fan is on?



Unless the door is the kind used to seal compartments on a ship,
plenty of air will get in under the bottom.

philo wrote:
On 03/09/2014 06:22 PM, bob haller wrote:
I have often wondered why bathrooms with fans dont have a air vent,
perhaps in the door to allow air flow when the fan is on?



Unless the door is the kind used to seal compartments on a ship,
plenty of air will get in under the bottom.

My thoughts exactly. Replacement air is not my concern.

I have often wondered why bathrooms with fans dont have a air vent,
perhaps in the door to allow air flow when the fan is on?

Usually, replacement air comes in under a door. For example, a 1" gap
beneath a 36" door is equivalent to a 6"x6" hole. Not to mention, most
buildings have a lot of air leakage around windows, pipes, wires, and other
penetrations. Intake air is usually not a problem.

However, modern structures are usually built tighter than they used to be,
so an intake air supply is often required. It's usually part of the heating
system, such as an air to air heat exchanger.

Here in Washington state, if we don't have a central heating system, we
have to provide fresh air intakes to each living space (bedrooms, and
living rooms). Then there must be an exhaust fan to pull fresh air into the
building and exhaust the stale air out.

When we built our house in 2004, we ordered our windows with special
screened vents at the top of each window. Then the exhaust fan in our
laundry room is setup on a timer so it runs at least 12 hours each day to
circulate fresh air. We don't see the vents inside the house because they
are located behind the blinds.

It seems kind of counter productive that we took so many steps to insulate
and seal up the structure of our home, only to have open vents in every
room. But the vents do ensure that we always have fresh clean air in our
house, with no mold or moisture problems. It was hassle to comply with when
we were building, but I've been happy with the system in real life. It's a
huge improvement over the stale, musty air in our older homes.

I do have to be careful when lighting our woodstove. If we turn on the
range vent before the fire is going enough to create a good draft up the
chimney, the smoke gets pulled into the room instead. Thankfully, I usually
start a fire before we start cooking, so that's rarely an issue.

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com

bob haller wrote:
I have often wondered why bathrooms with fans dont have a air vent,
perhaps in the door to allow air flow when the fan is on?

My bathroom has heat and return vents. Even if the door is shut, air will
come in, plus the little underdoor slot.

Greg

On 03/09/2014 07:22 PM, bob haller wrote:
I have often wondered why bathrooms with fans dont have a air vent, perhaps in the door to allow air flow when the fan is on?


Great minds think alike. I installed a full louvered door on our master bath years ago. Works great!