Alternative to bath vent fan? an idea or two.
 

I've been thinking about how I need to replace the bath exhaust fan in my bath room, partly because it's undersized and doesn't do a good job but also because we get a tax credit if it's energy star rated.
Now this got me thinking about how the bath fan really is just pulling conditioned moist air and dumping it outside, just to get rid of the moisture in the air, this seems like a bad idea, why not have a dehumidifier in the bath room on a humidistat or a timer so that instead of fogging up the windows it's pulling the moisture out of the air and drying it out, after all the air you dump outside has to be made up by non conditioned air some how, so in the winter that warm moist air is being replaced by cold dry air... in the summer it's being replaced by hot moist air.
Of course the bath vent fan also helps to keep the bath room from smelling bad, but there are room ionizers and UV light filters that can do the same thing, all while keeping your house sealed up and cozy.
So does anyone have a dehumidifier that they would like to try in their bath room while they shower? I would but I have a gym membership and haven't showered at home in months! it's almost worth it just in the water bill.

The easiest and best (in my mind) solution to excessive bathroom moisture is simply shower with the door open. I did install a nice quiet, energy star fan, on a timer, but never use it. The moisture dispersed throughout the house is hardly noticeable and actually a benefit in the dry winter months.

I do the same thing as hamsterpower. However, my house is not exactly leak proof, so its no big deal. I think if you had a tight house it wouldn't be a good idea, but if you have a tight house you should also have an HRV which should take care of it. Perhaps you could use a fan to cycle air into and out of the bathroom into the hall instead of outside?

I do have a dehumidifier for my basement though. I'll bring it up and run it while I shower to see how it does. I'll also plug it into the kill a watt and see what kind of power usage is there.

Empty Nest Shower.. :p
I do the same thing. Saves me money on running the humidifier in the living room.. :thumbup:

But, I do need to run the Sanyo setpoint up to 22c for a while before.
Just need the bathroom to be warm. Otherwise, condensation will form on the walls, glass etc..

You didn't say much about your bathroom layout...

But the moisture problem is from the shower.

If you contained the shower moisture to the shower, it would be a smaller problem.

My entire bathroom is integrated into my shower (width=31", length=51") all tiled, and I designed in a small double-hung window (the top of which is right up next to the ceiling) in the shower, so that I can open the top window and get naturally-convected, non-blower venting.

No electricity involved, works good.

-AC_Hacker

Well that is discussion for another time. :)

With the door open there is no noticeable condensation. When someone showers with the door closed and no fan, there is lots of condensation.

In the winter, my house gets so dry, I think the extra moisture helps. In fact I also run the (electric) dryer with the vent inside. (winter only)

I'll chime in on this since this is what I did this winter. In the winter I used the shower to humidify the house, I would run the furnace blower so the air would be distributed throughout the house. The master bedroom is connected to the master bathroom so I close the door to the hallway, open the one to the bedroom and keep the bedroom door shut. There is a furnace return in the master bedroom not too far from the bathroom door, although its near the floor it seems to help. In the winter, I start the furnace and hop in the shower, after 5-15 mins(usually 10, but before work its 5, on a leisurely day or sore muscles 15 mins). I have the furnace run for 30 mins minimum, so there is 15 mins of house circulation going on. If the house could use the heat and I'll be leaving the house, I'll let it run for an hour before setting the thermostat back to its normal temperature.

This works great when its below freezing out and the furnace will run for over 2 hours in a day but if it doesn't there isn't enough infiltration in the house(I have no ventilator), there is too much humidity. I've already got an issue where with the bathroom fan being on and the days being within 20 degrees of the furnace setpoint(furnace not running) where I can't keep the dew point above the point where any infiltration could cause insulation condensation. ...so I don't do it unless I need the humidity in the house.

I also recover all of the heat from the shower water by not draining the shower until the water is room temperature, also adds humidity to the house in the process.

In the summer you really don't want to exhaust the humidity into the house unless your air conditioner runs long enough to get rid of that humidity along with the extra humidity from any infiltration. The better insulated you have it the less your air conditioner will run and you might be battling a comfort psychrometrics issue. I try to keep my humidity below 30% as much as I can but once I get more insulation and correct any remaining infiltration issues in my house, I think I'll find it difficult to keep the humidity low because the air conditioner won't run enough.

Every house is a little different but outside of the coldest winter months or on the highest cooling demand days you might be adding too much humidity to the house.

A dehumidifier takes too much time and uses too much energy to get rid of the huge bulk load of humidity that taking a shower quickly adds to the air. I'd rather let the humidity escape and recondition the infiltration, I actually think it would be cheaper.

The two ideas I like best are AC_Hackers solution of having a bathroom window above the shower, assuming its waterproof and double-pane for efficiency. The other idea is the one where you enclose the shower area, that way a very small cubic foot area has condensed water vapor and in that small area, only so much humidity can be created. In that case one you open the shower door/curtain, the amount escaping will be minimal, probably to the point where you won't need to ventilate the bathroom.

I can't say anything about the smell issue, I usually don't use a fan and if my roommate doesn't like it, he just uses the other bathroom. ...as do I, but he usually uses the fan but it doesn't seem to help much and I doubt an ionizer or UV light would much either, but I suppose its worth a shot.

I do tend to shower with the door open when no one else is home, having room mates and friends who stop by randomly has made me cut back on doing that at times tho.
I also have the issue now of, we sealed and insulated our house, enough so that in the winter we do have moisture problems in the house that we did not have before so if I do take a shower in the winter and don't run the fan long enough some of the windows start to frost up, new quality double pane windows, so I run the vent fan till the bath room feels dry.
Part of what got me thinking about this was my brother is looking to buy a house and the houses we look at all tend to have moisture damage in the bath room, in my time remodeling houses I've come to realize that bath rooms are a bad idea mostly because of moisture.

I think the reason that you are finding moisture damage in the bathroom is that many people probably don't know that they are supposed to run the fan to draw that moisture out of the bathroom. I grew up in a house where we never used the fan when taking showers until a few tiny mildew spots started showing up on the ceiling above the shower. We figured out that we needed to use the fans right away and a quick shot of bleach shower cleaner got rid of it and it never came back. Many houses probably have a fan with too low of CFM to adequately ventilate the moisture but it depends on the size and design of the bathroom too. I've also noticed some frost on the windows on extremely cold days when I took a long shower and the steam would pour out of the shower area when I opened the curtain and got out, it would roll out of the door and fog the little 'porthole windows' and frost the bottom half. Those little things are a good indicator of when there is too much moisture, they would be the first and only windows to frost up if there was too much moisture, whether or not it was from the shower.

The house I grew up in had enough cooking with boiling water, showers, cooking with the oven, etc. to where there was always a thick layer of frost and ice at the bottom of the double pane windows. I never thought about it much, the house I'm living in now doesn't have that problem except for the two little windows high mounted porthole windows. I think keeping the house at a lower temperature in the window helps too because of the dew point swing.

I think keeping the house at a lower temperature in the window helps too because of the dew point swing.

I've found that a cold bathroom fogs up real fast (condensation all over the place),
when I start using hot water in the shower. Lukewarm is not as bad.
But, if I turn up the heat before taking a shower, there is a lot less condensation
on the walls, mirrors etc..

We were discussing this topic a while back, and the best idea I saw was the shower stall/tub top cover.
The steam-damp air stays inside as you shower. And, it's not all foggy,
because the air inside is warmed up too.


http://www.acquinox.com/prod_images/SBKS-ZQ-020_1.jpg