Controlling bathroom humidity & wet towels
jeffwatson
| Posted in General Questions on
How do you control bathroom humidity after you’ve left home or have gone to sleep, A/C is put on setback so it doesn’t come on, and you leave your towels to dry by hanging them on the back of the door?
I can’t tell during the daytime how bad the humidity gets (since the A/C pops on as we start getting home), but overnight, bathroom humidity shoots up & is consistently in the 60-70% range.
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Replies
Jeff. How do you ventilate the bathroom? Where do you live? Are you concerned about the bathroom humidity because of mold or mildew issues?
Could you put your bathroom vent on a timer switch? Or maybe replace it with a model that has a timer built in or runs constantly at low speed? Some even have humidity sensors to turn on automatically.
Drew,
A common solution is to install a so-called "delayed off" fan control switch. Here is a link to one of many such switches:
https://www.amazon.com/Air-King-AKDT60-Delay-Switch/dp/B000EVWFPS
Stick a dehumidifier in there. That being said, mold shouldn't grow if you can get things dry once a day.
Towel bar intead of hook?
If you're just using a hook on the back of a door, it's possible that you could get your towels to dry a lot faster by installing a towel bar that allows the towel to be spread out smoothly, increasing exposed surface area. And wider towel bars work better than skinny ones because air can more easily get between the two "halves" of the towel.
Getting delayed-off fan switches as others have suggested is a good idea regardless. If install one in one bathroom, you'll quickly install them in any others that you may have, whether they are full or half baths.
Steve:
- Ventilation: 70cfm fan, exhausts through the roof. Generally keep it running 10-15 mins after a shower
- Location: Chicago area, so air can be humid
- Mold/mildew concern: Yes. Our towels dry out for the most part from day 1 to day 2, but will still be a little damp. The floor towel/rug is consistently damp. I know these are scenarios mold will grow.
Drew/Martin:
- Yes we could use a fan that stays on longer, but what about the overnight case or "gone during the daytime" case where there's no bathroom usage and our not-fully-dry towels hang & windows are closed & A/C put on setback?
Jon:
- We have a "damp-rid" thing in there which I honestly don't know if it's reducing the humidity. I really don't want another power-hit with a compressor-based dehumidifier, as our basement dehumidifier is the next biggest energy consumer after our A/C.
Andrew:
- Yep, towels on a hook, wet floor rug just stays on the floor. Space is limited for a towel bar; we tried one early on but it took up too much space behind our door, and prevented the door from opening up fully (tub is right behind the door, so door can only open 90 degrees as it is).
An option to consider is a fan that can be set to a low rate continuously, with or without boosting it to 70 cfm for showers.
It doesn't make sense (energy-wise) to ventilate air to the outside if this causes air with a higher dew point to infiltrate. Inflow = outflow.
More air circulation between the bathroom and the rest of the house will lower the bathroom humidity. You're still paying to dry the towels, but it's hidden in the AC bill.
More air circulation within the bathroom will dry a towel quicker, reducing the opportunity for mold on the towel itself.
Jeff. The delayed-off switch Martin recommend sounds like a good idea. You also may want to buy an humidity monitor to keep an eye on your interior levels. The inexpensive greenhouse monitors at HD are actually pretty accurate (at least based on the couple I use). It may be you need to set the temperature a little lower on AC during high-humidity weather. A couple of tweaks may be all you need to do to solve this particular problems.
If you have access to the bath fan exhaust ductwork, check to make sure it is a fairly short and straight run to the outside.
Do you leave the bathroom door open or closed when not using the bathroom? If you have been leaving it closed, try leaving it open.
How is the humidity in the rest of the house?
Also, have you checked whether the fan is actually moving air as opposed to just making noise? One quick test is whether it creates enough suction to hold a piece of toilet paper
I have around 5 temp/humidity Accurite's around the house. The bathroom is consistently higher in dew point. Bathroom is usually 2 degrees cooler because the furnace/A/C is right under the bathroom. Once the A/C comes on, yes I can see the humidity readings drop before my eyes, but a 3 ton A/C unit is expensive for my tiny 5x7 bathroom. Forgot to mention, the main floor area the 900-1000 square feet range.
Generally the bathroom door stays almost closed right after a shower but then we open it it fully when we turn off the fan.
Yes the fan is moving 70cfm, this was measured with a duct hood during my last audit. It's rated at 80cfm. The duct is rigid metal, one 45 elbow going straight to the roof (total length about 6 feet, low pitch roof). When the door to the bathroom is closed, I can feel the air rushing through the cracks pretty good where the door meets the frame. Not to mention the amount of dust that I have to continually vacuum out of the grille & motor itself every month.
I have the problem when the A/C is on setback overnight & during the daytime business hours. Yes I could stop doing that but that's a ton of energy. The bathroom humidity is fine in the evening hours when the A/C runs.
Do you guys leave your towels hanging to dry in the bathroom? What about wash cloths & bathroom floor mats/rugs? I come from an apartment life where the radiator was how towels got dry? Now that I have a house & have read up on home performance, am I doing it all wrong?
Jeff,
Yes, most people hang up their towels and washcloths in the bathroom to dry.
Yes, towels and washcloths dry much more slowly during the summer (especially when the weather is hot and humid) than they do during the winter (when most heating systems keep indoor RH levels low).
In past years, before the invention of air conditioning, people took these facts for granted. Your salt shaker won't work in the summer. Your towels take forever to dry. That's life.
Nowadays, anyone who is irked by these physical facts can operate an air conditioner or a dehumidifier. That takes energy. If you don't want to operate your AC, that's fine. Mix up a glass of lemonade, sit in a rocking chair on your front porch, and say hi to the neighbors walking by. That's summer, the old-fashioned way. (Oh -- and get used to damp towels.)
Here is a radical idea (which my wife unfortunately does NOT subscribe to:) After showering, before stepping out to dry off with the towel, ring out the rinsed clean washcloth and rub body partially dry with the washcloth in the shower before stepping out and grabbing the towel. Just takes a few seconds, and then the drying load of the towel is significantly reduced, as it has much less water to surrender to the drying process, reducing the humidity contribution of the wet towel to the bathroom. Takes a few seconds longer, but it really works!