When it comes to bathroom exhaust fans is more CFM better and worth the money?
I have a small bathroom, 5′ x 7′, so it’s <50 sq. ft. Located in the middle of the house with no windows and 3 women who think long, hot, showers are a constitutional entitlement. I am about to spec out a re-model of the bath and was questioning the size of fan to install. Should I go with the 50 CFM or bump it up to >100CFM? Any suggestions would be appreciated.
Also, any good design sites with ideas on a small bath remodel?
Replies
50 CFM is minimum code, I believe. Even a small bump up, to 75 or 100 CFM, will make a major difference in how well the steam is cleared from showers. You can, of course, install a mega fan if you want, but too much air movement can be as unpleasant as too little.
Also, beware of just venting the fan into the attic. Probably not as bad in S Cal as in other places, but still not a good idea.
I would install one with a humidstat or add one on so that it runs long enough to clear the air.
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Here's the sizer sheet from panasonic. http://www.panasonic.com/consumer_electronics/ventilation_central/howtosize.asp
Also, check out their info, questions page, etc.
In combination with the fan, I like the leviton timer switches. Just push the button and forget about it.
http://www.energyfederation.org/consumer/default.php/cPath/39_766_128
Edited 10/22/2007 7:39 pm ET by DDay
What Dan and Bill said.
And keep in mind that the Panasonics are very quiet. I went with the quietest Broan fans and have always regretted it. Also, I've heard that good installation practice is to isolate the nailing flanges from the joists with a bit of drywall or closed cell foam to stop acoustic bridging of motor noise, not that you'd have much of this with the Panasonics. Fantec is another name that seems to be respected around here.
Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I'm with you on the noise. My experience is that the quieter the fan, the longer you are likely to run it. I can't wait to turn off my bottom of the line Broan - whether the moisture is gone or not.
Thanks for the info and the links. I like the switches, pricey, but nice. I am going with the Panasonic Whisper Green fans, just need to decide on a size. According to the sizing chart I need the 50 cfm, but I think I will bump it up to at least 110cfm to move the air faster. I only have an 8' run to my roof vent and it's a straight vertical shot.
But with the local wildfires burning all around me, maybe this won't matter in the morning!
Thanks again
Experienced, but still dangerous!
My bathroom is exactly the same size an set up as yours: totally interior, 5x7 (including the tub).
I put in a 70cfm Broan with about 12 feet of duct run and wish I had gone to at least 100cfm. I still have some pretty serious steam issues.
Good Luck
I put in a 70cfm Broan with about 12 feet of duct run and wish I had gone to at least 100cfm. I still have some pretty serious steam issues.
Did you use good rigid ducting, metal or pvc? That flexy stuff so many people install is high-resistance bad news.
I have seen so many bad installations where the fan isn't doing the job because the white plastic or hardware-store variety metal flex is looped and sagging all over the place, sometimes even crushed. Even when it's run straight it offers a lot of resistance to air-flow.
Ducting is almost as important a part of the system as the fan itself.
Ed
Edited 10/23/2007 6:56 am ET by edlee
yes the flex stuff, but other than a 90 at the fan it completely straight. Now that it is cool again I suppose I could get up there and re-do it in non-flex metal.thanks for the insight.
Definitely. Better flow, less noise, fewer problems with condensation.
If your view never changes you're following the wrong leader
PIA, right?
Anyway, I like to use 3" or 4" Schedule 20 white PVC. It's cheap, easy to work with and smooth inside. Sometimes I use a bit of flex coming out of the fan to get up out of the joist bay.
Ed
Everyone forgets makeup air in centrally located baths. If you have central heat, the furnace duct will give you make up air. If not, cut the door bottom high to allow air in. Air can't go out unless some air goes in. Otherwise you are pulling on a vacuum. Cold make up air is not great as you now condense out more moisture in the duct or room.http://www.etherhuffer.typepad.com
Panasonic units are definitely the best .. humidistats only tend to last 2 or so years, be prepared to change them, or install a timer switch. I installed the biggest Panasonic avail thinking more is better, and regret it, the duct is huge, 6", not much room to insulate around, the fan's damper is clipped along the edge so there is always air flow, the vent cap damper also has a similar design. Both companies say the other co's damper should be 100%. You want to avoid condensation build up in between fan and vent but there is too much flow for my comfort, I will probably modify the fan's damper so that it is 100%.
ps .. if your fan has a night light wire it and the fan together, they are really quiet so this is a good reminder when the sucker is running ..
Edited 10/23/2007 11:30 am ET by wane
I bought 3 Panasonic units and as good as they are I hate them. I built one that is much quieter and look forward to the day that I really get sick of it and build another. I'll rip the blower assy out of it and keep the rest.
With respect to noise, I've noticed that a lot depends on the depth of the unit. Shallow units will be noisier, and an extra 2-3 inches makes a lot of difference.
If your view never changes you're following the wrong leader
These are all good sized units. I recall them being all of 10" tall at a minimum. They are all metal piped with the least amount bends as possible and the joints taped. Piping is pitched to avoid drain back or leaks mid span. It does run thru non conditioned, very cold attic space. (Northern Maine)It's clearly a case of being spoiled by the roof top unit in our primary home. It's a flat roof so there may be all of 24" of metal pipe running into the blower assy. I bought it at Grainger and my roofer installed it in about 2 hours when he was doing a PM on the rubber.Panasonic is clearly better than the competition. It's not however the final word. The costs were close enough to be equal.
"I bought 3 Panasonic units and as good as they are I hate them. I built one that is much quieter and look forward to the day that I really get sick of it and build another. I'll rip the blower assy out of it and keep the rest."Now there's a statement that makes me want to hear more. Care to elaborate?
BruceT
I'm off to a meeting now and will be on the road most of Wed. If you don't hear back please tickle this thread and I will explain in detail what I did.
Check out these back-draft dampers. I put them in when I use an inline duct fan, like the Fantechs. They have springs and a gasket, they're pretty nice.
http://www.energyfederation.org/consumer/default.php/cPath/86_744_113