Another question - I read duct must be vented to the atmosphere (roof/end wall) and never through attic, soffits, etc. However, it appears inline fans state the motor is remote (and often placed in attics) - is this okay??

There are two basic bathroom exhaust fans: Mount the fan in the bathroom ceiling, attach flex duct and route the duct to the outside.

A little more complex way is to mount a grill in the ceiling, a flex duct is attached to the grill and is attached to an 'inline' fan that is in the attic. The output of inline fan is ducted to the outside. This may be more quite since the fan is in the attic, not the bathroom. It is possible to connect several bathrooms to one inline fan.

The exhausted bathroom air must be ducted to the outside, otherwise moisture would buildup in the attic.

I would use a digital timer - they come with various time settings.

You can see some pictures / products here:

Regarding safety, efficacy, energy use - is there any difference with ceiling mounted vs inline/remote?

And to use an inline/remote fan, do you have to connect multiple bathrooms or can you vent just one bathroom? if venting more than one bathroom, what is the furthest distance the bathrooms can be from one another and this system still work and be effective? (i.e. in my situation, the master bath is on an exterior wall, next to the master bath is the master WIC and next to the WIC is the main bathroom for the upstairs - so the bathrooms aren't directly next to eachother) - can you have an inline/remote fan with this set up?

2. Are you going to have an HRV/ERV? If so one of your options might be just to have a boost function on that (exhaust from the bathroom), that is what we have. If you are not going to have an HRV/ERV then just ignore this.

You might also cross-point to the HVAC forum for more responses. Or try at greenbuildingadvisor.com.

Good luck.

I think that you are over thinking it. Get a fan from a reputable company that is advertised as being quiet and you probably won't be able to hear it unless you really listen for it.

I always put my bath fans on 1 hour spring timers and I think it works well. If it's just on a regular switch, it will run for hours until someone finally goes in the bathroom and notices that it's on. A humidistat could be wired in as well so that if either is on, the fan will run

We got a Delta Breeze Humidity-sensing fan to install in our bathroom (when we bought the house it had none). It is very quiet and works well, better than any other fan I have had so far. In our (small) bathroom the mirror is not fogged when I step out of the shower.

Many of these issues are location dependent so without that information you will get very general answers.

I don't recommend combining exhaust fans with lights.

I don't recommend combining multiple bathrooms on one fan.

I don't recommend plastic flex-duct for an exhaust duct. If a steel duct is not feasible use a metal flex-duct.

Thank you for everyone's comments. Location is northeast Ohio; Sanford W. - why do you not recommend combining exhaust fans with lights? I've seen people install fan + light directly in their shower - this doesn't seem ideal - any thoughts on this? (should place the fan outside the shower, but close by?)

iMO the fan-lights are ugly and provide poor lighting. They must also be marked by a testing agency as appropriate for use in a shower area and must be on a CFCI circuit.

I use an inconspicuous recessed line or low voltage wet-rated light with a lens in the shower and an inconspicuous Panosonic Whisper Fan outside of the shower.

Great. Thank you for all the comments/explanations.

Just curious - does installation cost differ between ceiling mounted and inline? if so, by how much approximately?

Hi,

We routinely install bath vent fan/light combination units over showers. If you're going to install a recessed light over a shower, why not combine it with the vent function? It locates the vent fan closer to the source of moisture that you're trying to vent and it's less obtrusive than a separate light and vent fan. Panasonic makes a couple of different ones. Do pay attention to the length of the duct from the vent fan to the exhaust point--shorter is better.

Best wishes.

When you speak of inline fans I assume you mean they will be remotely located which means providing access to them possibly in tight spaces. This may increase the cost.

As for fan-lights in the shower, it seems ineffective to try to remove water vapor laden air from the shower since most of it will condense on the walls before that can happen anyway. My goal is to remove humid air from the vanity area and allow fresh air drawn from the door undercut to reduce fogging of the mirror and window glass. The entire bathroom will eventually dry out if you use a fan with a built in timer and/or constant low speed feature like Panosonic's WhisperGreen series.

I have yet to find a fan-light combination that performs as well as separate units. Here are my criteria:

no CFL or LED lamps (LED inappropriate in a bathroom; CFL inappropriate in a house)

Max sound rating .8 sone

max grille size 13x13

flush with ceiling

variable speed fan with timer

Panasonic makes a recessed spotlight-fan combination (FV08VRL1) but it uses a CFL. I suppose a halogen PAR lamp could be substituted because the CFL is probably only needed to get an EnergyStar rating but I am not comfortable recommending it.

To reduce fan noise it is important to reduce back-pressure by using larger metal ducts.

Warm, moist air is less dense than dry air. Removing moisture-laden air close to the source is an effective strategy-- both in theory and in practice. While a vent fan in proximity to a shower can work fine in many cases, there are conditions where it simply won't. One such case is where the shower is a fully tiled floor-to-ceiling shower with a long entry so it doesn't need a door. You need air to circulate in the shower and without locating the vent fan in the shower to draw air in the shower is likely to become its own ecosystem.

A reputable local mechanical contractor can size the bath vent fan and associated duct work for you and make a recommendation about where to best locate it.

Best wishes.

Moisture in air in the same room will quickly become balanced and will dry at about the same speed regardless of the fan placement. But that will take a little longer if the shower space is separated from the rest of the room by walls to the ceiling and a vestibule with the fan in the main part of the bathroom. In that case both spaces should have fans or vents from one remote fan in order to reduce the time a single fan would have needed to run to dry the space.

But I would not combine the light with the fan in any circumstance or put them on the same protected circuit. If I wanted to exhaust a shower enclosure I would use a remote fan; IMO, GFI protected motors in a shower enclosure simply a bad idea.

Show me a fan-light that doesn't look like it belongs in a Motel 6, provides attractive light, has a built-in timer and is quiet. I may have missed it.

A bath vent fan isn't an architectural focal point unless, perhaps you live in a chateau or the Ritz Carlton. That said, I do have a preference for Panasonic's model FV\-08VRL1 combination recessed light/fan units because they are unobtrusive, function well, and are very quiet. We've installed dozens of them over showers and tub/showers without a single performance issue or complaint\-\-even from owners of $1.5 million homes.
I'm not an electrical engineer, but I trust the UL certification of the Panasonic unit for its intended installation above a shower or tub/shower means it's perfectly fine in that application. If you want to wire the fan and light on individual circuits you have that option available to you.
In my view, control devices should be separate from whatever they control\-\-not built in. With regard to a bath vent fan, you could choose a simple switch, timer or humidistat to control the operation of the fan depending on your preference, the application and your budget. If the control device fails, you can replace it without the need to replace the entire fan/light.

I can't really answer your questions, but did want to share that we have a unit in our attic that is a heat recovery thing...in addition to being more energy sensitive, the thing hangs off the rafters on chains and is so quiet, that the only way we knew it was working was to actually test it. I believe it is a fantech unit.

Thanks! phd12 - are you installing in the shower or right outside?