Bathroom Exhaust Fan

[buell]

I have an older home with a bathroom that has poor ventilation which causes shower steam to coat the walls with moisture. In effect this yields unwanted mould on the bathroom ceiling and other places like tile grout and shower curtains. The differences between my bathroom and a large petrie dish are begining to blur. I have accepted the fact that I have to install an exhaust fan come spring time so I am begining to do a bit of research on the easiest method to install an exhaust fan in an older home. I came accross this PDF

which is a good start. After reading this I realized that the most effective way to install an exhaust fan is on an exterior wall, exhausting directly to the outdoors. Does any one see any potential issues besides a proper way to insulate? Looking forward to your replies.

Rainer

[Rileyesi]

Here are a couple of thoughts (I didn't read your link, so sorry if this is repeated!)

Assuming your bathroom has access to an attic (i.e. if the bathroom ceiling is the floor of the attic)...

If you have roof ridge vents and if you have access to the bathroom ceiling, you can vent the fan near the ridge vents. Just take the tube from the fan and mount the other end as near the ridge vent as you can. The theory is that hot air rises and so most of the moisture will go out the ridge vent. This will allow you to place the fan on an interior wall or the ceiling rather than an exterior wall.

Maybe I am using the wrong term. By ridge vent I mean that your roof has one long vent running along the peak of the roof.

Another tip, I tied the electric power to the fan to a light in the bathroom. That way, any time the light is on, the fan is on. With the logistics I had, it would have been a royal pain to make a switch for the fan itself.

One last thing, if you do vent out an exterior wall, look to see if you have soffit vents. A soffit vent is located on the bottom of the eaves of your roof. These soffit vents are the air intake for your attic. You do not want to vent the steam of the bathroom near those soffit vents or you will be pumping moisture into your attic.

Hope this helps.

[twfsa]

I have the same problem with steam and moisture build up, and I do have a exhaust fan that is vented to the soffit eves.

I turned down the temp on the water heater, and that has helped but I need a more powerful exhaust fan, and have not found one as of yet. I have tried to keep the bathroom door shut when not in use, to keep it and the walls and tile as warm as possible, so there not that much sweating when the shower is used.

The fan I have is for a 50sq ft room, but the larger fans don't seem to pull that much more air.

Tom

[RBM]

[trader4]

"Another tip, I tied the electric power to the fan to a light in the bathroom. That way, any time the light is on, the fan is on. With the logistics I had, it would have been a royal pain to make a switch for the fan itself."

I would advise against doing that as it wastes energy in two ways. First, there will be lots of times when you want the light on, but don't need the fan. With the fan forced on with the light, it's drawing cooled/heated air and pumping it out of the house. Second, when you want to leave the fan on for 10/15 mins after taking a shower, the light will have to be on too.

[William W. Plummer]

Insulating the cold walls is where you should start.

If you install a fan, connecting it to the bathroom lights is fine. I assume you don't spend a lot of time in the bathroom. The fan doesn't have to run very long to get the relative humidity down to the point where condensation won't be an issue. Ex: My bathroom is 10' x 4' by 8' which is 320 cu ft. So, a 100 cfm fan will cut the humidity to 50% in

3 minutes.

[News]

Sizing the fan is very important. When I replaced my exhaust fan with a quieter fan I found a great "how to" on sizing.

If you install an undersized fan, the fan will run, but it will not exhaust much air.

Regards, John

William W. Plummer wrote:

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[nicksanspam]

Better yet, connect it to Herbach and Rademan's [phone]

nice brass $4.95 Navy surplus humidistat (or is that a DEhumidistat? :-), their item number TM89HVC5203, with a 20-80% range, a 3-6% differential, and a 7.5A 125V switch that can be wired to open or close on humidity rise.

There's a lot missing before your "So" :-)

Nick

[John Harlow]

Same here.

I just went to Lowes, bought a $15 fan and installed it directly above the bathtub. Wired it in to come on with the light as well. Right now it vents into the attic; when it warms up outside I will put a soffet vent in, although my last house (much smaller attic) had one vented into the attic with no ill effects.

It took about 45 minutes to do. No more steaming of the mirrors or windows, nor shit smell.

[Duane Bozarth]

...

Be careful to not wait long for warm weather...cold weather condensation can soak your insulation in a real hurry...as for no ill effects previously, I'd consider that a real miracle or your previous attic was extremely drafty.

[Dan]

Dumping humidity into the attic is a real bad idea. I know that some municipalities allow it but, doing home inspections, I've seen mold growing all over the sheathing near the outlets. I wouldn't do it!

Dan

[Terry]

We find it a good idea to run the fan after using the toilet also (To remove odour; to be delicate about it!). BTW even if electricity costs you ten cents per kilowatt hour, running say a

100 watt light bulb along with the fan for an additional quarter of an hour will cost. 1/4 x 100/1000 x $0.1 = 0.25 cents! (one quarter of a cent!) Even if you ran the 100 watt bulb for 'one hour' following a shower it would cost (at 10 cents per k.watt/hr.) = 1 cent. That's hardly significant; since one is also running the fan to avoid potentially costly mould!

[MUADIB®]

As With the other posts, I will give my "what I did"

I just bought the house in May. Within days, the fan in the "middle bath quit, as well as the heat lamp. It is an all-in-one type fixture. Since there's only two of us ( ideally ) living in the house, I just left it alone thinking "I'll fix it another time after a bit of other items to be taken care of are done." That was ok for about three months, then the other bathroom fan quit. just as the weather was turning cooler here in Dallas , and the Humidity started building heavily and I had no way of removing the humid air.So............

I went and looked at fans and Heaters and fan/heaters, and decided I wanted two seperate items because of the way these had died..........

In the master bath I wanted to be able to move air quickly so as to not have any need for leaving the fan on very long, mostly so I wouldn't forget and leave it on for hours , or all day while at work or something. I bought a "next to industrial strength) 180 cfm exhaust fan, and a heater that is like a coil in an old GE clothes dryer with a fan mounted in it to circulate the heat downward...........both were pricey, but they were exactly what I wanted.

In my case the wiring was already there and just needed to be split from one fixture into two, and a junction box to extend one so I could put the exhaust fan OVER THE TOILET. All accoplished fairly easily.

RESULTS: I now have a nice warm bathroom if I warm it for a few minutes in the morning before I shower. I now have an exhaust fan that sux all the humidity out of the bathroom in about 8 minutes after I turn on the fan..........Timer switch to come.

HOME DEPOT has all the stuff needed to do all of this install, even if there's no wiring in the wall or ceiling. Worse case scenario, surface mount your wiring in conduit.

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MUADIB®

one small step for man,..... One giant leap for attorneys.