Bathroom Exhaust Fan

[D45]

Trying to figure out what to do with humidity/moisture in my bathroom

I have a NuTone exhaust fan rated for 80 CFM

My bathroom is 11' x 8' with 8' ceilings

According to online calculators, I need atleast 93 CFM in this room

I guess the contactor installed what he had? Code issue? Anyways

So, will installing a 100 CFM bathroom exhaust fan help me out at all?

20% increase in CFM

 

[rlitman]

Is this a problem with condensation in the winter following a hot shower? Perhaps it's a heating or insulation issue, and the bathroom is just cold, leading to condensation.

 

[karoc]

Big box stores just don't carry quality EF's cause most people don't give it any thought. I would check at your local plumbing supply store which some do have show rms and some will have brochers on what they sell.

 

[LXCam]

When I redid our master a few years ago I bought a Panasonic unit with a built in automatic condensation sensor. That thing is awesome, dead quit and works like a rockstar. I don’t remember the cfm but did oversize it a tad. If 100cfm is enough, then 500cfm is better right?

 

[roc_on_the_rocks]

I'm with rlitman, can you better define this humidity/moisture problem?

As a reference, my bathroom is 72 ft2 (6' x 12', with 7.5' ceiling), no issues with a 70 CFM fan (Broan 655).

You could also check the exhaust piping. Another thing, is there a whole house humidifier?

 

[gagecalman]

I have a fan with a heater.
In the winter I run the heater and it takes care of the humidity.

 

[Kaizen]

Also would look first at the exhaust and exterior flapper door. You would be surprised how many of these things are not even vented. Use straight run of solid pipe if you can.
If you have a flex pipe in attic it’s probably full of water and acting as a plumbing trap


Sent from my iPhone using Garage Journal

 

[Shiftless]

Our smallest bathroom is 6.5 ft. x 6.5 ft. I installed a Panasonic 100cfm fan controlled by an automatic timer switch. Straight solid vent pipe to the outdoors. I set it for 1 hour at the start of a hot shower and that handles all the steam and condensation.

But hey, this is GJ right? Where overkill is often deemed barely enough.

I put one of these 36 inch fans in the hallway to exhaust hot stale air from the house and attic during our warm season. (No central A/C )

 

[roc_on_the_rocks]

Our smallest bathroom is 6.5 ft. x 6.5 ft. I installed a Panasonic 100cfm fan controlled by an automatic timer switch. Straight solid vent pipe to the outdoors. I set it for 1 hour at the start of a hot shower and that handles all the steam and condensation.

But hey, this is GJ right? Where overkill is often deemed barely enough.

I put one of these 36 inch fans in the hallway to exhaust hot stale air from the house and attic during our warm season. (No central A/C )

I'm probably minority here, I like the smallest fan that does the job. I don't like the idea of pulling cold makeup air into the house in the winter, or hot air in the summer.

 

[rlitman]

I'm probably minority here, I like the smallest fan that does the job. I don't like the idea of pulling cold makeup air into the house in the winter, or hot air in the summer.

If that's your concern, run the exhaust through an HRV.

 

[D45]

Is this a problem with condensation in the winter following a hot shower? Perhaps it's a heating or insulation issue, and the bathroom is just cold, leading to condensation.

Basically yes, I did not notice it during the summer/fall months

 

[D45]

I'm with rlitman, can you better define this humidity/moisture problem?

As a reference, my bathroom is 72 ft2 (6' x 12', with 7.5' ceiling), no issues with a 70 CFM fan (Broan 655).

You could also check the exhaust piping. Another thing, is there a whole house humidifier?

I will check the exhaust piping.............I dont think there is a whole house humidifier

This is actually my girl's house, just brain storming fixes to help her

 

[roc_on_the_rocks]

I will check the exhaust piping.............I dont think there is a whole house humidifier

This is actually my girl's house, just brain storming fixes to help her

Before taking more drastic measures, I'd suggest bringing a small heater to the bathroom and setting it to around 75-80F before/during showers, I think that might fix the problem. Then turn the heater off and open the door after shower. I actually like bringing some of that humidity into the bedroom in the winter, it's pretty dry here now (35%).

Good luck.

 

[Hpozzuoli]

Is the exhaust going thru the roof, out the side of the house, into a soffit vent, or dangling in the attic? If the fan is too weak to push the air thru the hose and out the exit, the air will back up and not circulate. Biggest issue I see besides not venting correctly is undersized fans. People buy the cheapest fan and wonder why they have black mold everywhere.

You also need to run it while showering and once your done for 10mins.

 

[firebirdparts]

You need to let some air in and out. It may just be sealed up pretty good. Do you have forced air going in there? Any dampers? Are they closed?

 

[alfazer]

Make sure you have a good air intake, like a space under the door or an open window. All that CFM has to come from somewhere or your fan won't be able to breathe.
EDIT, I just saw firebirdparts post, as I posted.

 

[engineer2]

I have some experience installing different types.

If there is a shower, you need at least 100-120 cfm even if it is a small bathroom.

The humidity sensor types are nice especially with forgetful kids.

Ideally the fan should be over the shower, or as close as practical. Ones with a light will brighten up the shower.

If you have a 100 cfm going out, 100 cfm needs to get in. Sometimes the crack under the door isn't enough. It will pull enough out of the air register or air return if you have one. If you don't have enough make-up air, you need to find a way to let air into the room. Cut a bit off the bottom of the door, add an air return in the plumbing wall or chase. Lack of make-up air a common cause for steamy mirrors despite a big fan.

Flex ducts have terrible loss of flow over distances. Another common cause for steamy mirrors despite a big fan. Try to run a straight metal pipe with minimal elbows. Use 4" if possible and definitely with runs over 12 ft.

Where is the air exiting the building? Some builders carelessly dump it in the attic or eave vent. It needs a proper vent. Metal ones hold up better. Around here the cheap plastic ones hold up about 5 years before they rot away.

If your bathroom adjoins an area where people congregate, a noisy fan is desirable because it will mask the sound of people tinkling and/or farting.

Fans require maintenance, you need to open them up and blow the lint and dust out now and then.

Can't beat Panasonic for quietness.

 

[rcktpwrd]

I installed a couple of bath fans in the spring, got Air King brand from Lowes, they work great! Their customer service was excellent as well had an issue with one after instillation and they took care of it with no problems!

Installed two of these in 130cfm, in two different bathrooms: https://www.airkinglimited.com/product/energy-star-eco-exhaust-fan/

 

[CTyankee]

You need to let some air in and out. It may just be sealed up pretty good. Do you have forced air going in there? Any dampers? Are they closed?

Make sure you have a good air intake, like a space under the door or an open window. All that CFM has to come from somewhere or your fan won't be able to breathe.
EDIT, I just saw firebirdparts post, as I posted.

Had a HOer who was having a similar problem with a fan with CFM that should have easily been able to handle the moisture. Trimming the bottom of the door was the solution. FWIW, where a male showering might never tax the exhaust fan...a female using it(potential longer showering time) could.

 

[dogdog]

you better get the 300CFM one just to be sure...

 

[lml999]

If your bathroom adjoins an area where people congregate, a noisy fan is desirable because it will mask the sound of people tinkling and/or farting.

We have a powder room near the kitchen, with a noisy fan. I asked an electrician if he would change it for a nice quiet Panasonic fan, and he mentioned the same issue.

Personally, I don't care, but...I'd probably be the one in the powder room, not the crowd in the kitchen losing their appetites.

Oh, and we have a full bath in our finished basement. Occasionally I've found the exhaust fan running long after guests had left. So the electrician installed a pushbutton timer switch...push the bottom button and you get five minutes, press the top and you get 20 or thirty. No matter which button you push, the fan will eventually go off...

 

[yeldogt]

I always use Fantech -- they make an inline ..my favorite is the exterior mount. No noise ...

A nice way to vent a bath is to have one inlet in the shower and another by the toilet ... "Y" to the fan.

Fantech makes 4" round inlets

 

[Juiced06GTO]

Agree with running a Panasonic, super quiet and seem to hold up well.

 

[rsparks64]

When I redid our master a few years ago I bought a Panasonic unit with a built in automatic condensation sensor. That thing is awesome, dead quit and works like a rockstar. I don’t remember the cfm but did oversize it a tad. If 100cfm is enough, then 500cfm is better right?

\

We did the same thing as LX in our last house. You could adjust the unit for a certain humidity level and it would run until that level is achieved. It also had a motion detector that would turn the fan on when someone walked into the bathroom. I don’t recall if it was Panasonic though.

 

[Joemctag]

Maybe this is one of the few things I’m a fanatic about. Bathroom isn’t air-conditioned or heated. Before a shower, I turn on the exhaust fan (a good one, through the roof), open the window and put a box fan on the floor set on high to move the air around so no condensation or damp spots in corners. Leave all that running til at least 10 minutes after my shower. What somebody said about water condensing in the cold flex duct in the attic is right. So run it so it’ll drain back to the fan or down out of your wall or soffit vent

 

[nadogail]

An open window in the bathroom will aid in moisture control.

 

[rallenc]

I always use Fantech -- they make an inline ..my favorite is the exterior mount. No noise ...

A nice way to vent a bath is to have one inlet in the shower and another by the toilet ... "Y" to the fan.

Fantech makes $" round inlets

I've used Fantech and put them on Occupancy sensors; stays on about 10 mins with no movement. Also have variable speed controllers (not dimmer switches) on the fans, just in case.

 

[CraigStu]

Our previous house had all the 2nd floor exhaust fans run into straight metal pipe right up to the roof ridge vent. I thought that was a great idea. The current house has them run nice and straight but w/ two 90deg bends out to the perforated soffit. Wish I had thought to request the ridge vent method. I also have them on timers. I did that after I retired and realized my wife left the fan on 50% of the time when she went to work. But at least that was better than turning them off too soon.

 

[yeldogt]

I've used Fantech and put them on Occupancy sensors; stays on about 10 mins with no movement. Also have variable speed controllers (not dimmer switches) on the fans, just in case.

I use the Decora sized timers .... Leviton makes a nice one. 5/10/15/30 min works great and you can do it as a three way in a bigger bath where you may need to turn it on at both the shower and toilet. The exterior mount 4" XL has lots of power and splitting it into twin 4" inlets eliminates the noise and get you great coverage -- the small inlets are not noticeable and you can place one right in the shower.

For the tradition type -- I agree on the Panasonic. It's what I use in my rentals or if I'm replacing one and not remodeling ... new I always go remote or exterior.

 

[Nick Danger]

I use the Decora sized timers .... Leviton makes a nice one. 5/10/15/30 min works great and you can do it as a three way in a bigger bath where you may need to turn it on at both the shower and toilet. The exterior mount 4" XL has lots of power and splitting it into twin 4" inlets eliminates the noise and get you great coverage -- the small inlets are not noticeable and you can place one right in the shower.

For the tradition type -- I agree on the Panasonic. It's what I use in my rentals or if I'm replacing one and not remodeling ... new I always go remote or exterior.

I went with a Panasonic fan and Leviton 5/10/15/30 timer combination. I have been very happy.

The only downside is that we have to put a little sign on the switch during parties so people know that it's the fan switch.

 

[LS6 Tommy]

Another vote for Fantech. Quieter than a Panasonic, (can barely hear a little air noise from either of mine) more CFM, less expensive, much longer lasting. No brainer.

Tommy

 

[jonshonda]

Without spending money, things to check are that the fan seems to be operating correctly, check the vent outside, and see if you can find out how it is routed and if that is straight.

Then close the door and turn the fan on, feel around the door for air rushing by your hand. The fan needs an intake source to work properly. I have found in our small bathroom, that leaving the pocket door open slightly help the fan work.

If those things check out, look at installing a more powerful fan. Our first house I went with a 130cfm w/ 6" ducting (small bathroom) and that took care of it. Also know that you should run a timer, and that the fun should run for a minimum of 30 minutes after your shower is done.

 

[PhantomEB]

The one in the bathroom yet to be built is still NIB so I probably will just buy a matching one then put one over the ******* and other at the other end where the soaker tub is to go. Sliding window in that room so I really don’t want humidity issues with the window down the road.

It’s next to my rec room so any fan noise will be drained out with turn the stereo up!

 

[yeldogt]

The one in the bathroom yet to be built is still NIB so I probably will just buy a matching one then put one over the ******* and other at the other end where the soaker tub is to go. Sliding window in that room so I really don’t want humidity issues with the window down the road.

It’s next to my rec room so any fan noise will be drained out with turn the stereo up!

Look up the fantech -- you can have two inlets on one fan. As i said above they make an exterior unit that I like to use if possible -- I hard pipe or use 4" PVC