Humidity Control?

[kari]

"Outlets" include clothes drier, furnace, fireplace, washroom and stove exhuast vents.

[Doug]

Originally Posted by TheReefGeek

I was just going to run the bathroom fan 24/7. This winter is crazy warm, so I am not too concerned about the cold air coming in. Next winter might be different.

How effective are de-humidifiers?

That will remove humid air alright. Just remember the negative balance thing. Good thing its warm there.

One could take an HRV unit with them but depending on how its installed, a lot of structure will be left. It should enhance the value of a house, enough to cover the cost.

De-humidifiers work fine. Just not the most energy efficient things. I depend on one during the summer however, along with AC. Units like HRV,s are not the best in the summer when the outside air is very moist also. However most people with decent central air units seem to have no problems, esp. the ones that have their hoods andso on vented outside. I know several that also vent their large beckett skimmer outside also.

[hawk]

Venting with a bathroom fan will work as long as the humidity level outside is lower than the humidity in your house. Being in Edmonton this is probably your case, but for those of us in more humid locals this simple fix can actually make matters worse. For example, here humidity outside right now is 86%. If I ran a bathroom fan 24/7, I would be exchanging humid indoor air with outdoor air that is even more humid, not a good trade.

[BMW Rider]

The HRV will work the same as a exhaust fan to lower the relative humidity, the HRV just recovers most of the energy used to heat the air in the house before it is exhausted while using no more energy to run. Even here in Calgary the outside humidity is 60% but that is at a temperature of less than 5 degrees. That same air at 20 degrees would be less than 10% relative humidity. Warm air has a greater capacity to hold moisture, Thus, it would contain 10% of the total capacity of water that it could hold before the water condensed out once warmed to room temperature. So even at 86% RH outside, you would gain significant drying of the inside air.

Here is an interesting chart to see just how much change in relative humidity warming the air makes.

http://www.skuttle.com/humid.html

[TheReefGeek]

There is nothing close to where I would be punching the hole, so I think I am safe there.

[hawk]

Originally Posted by BMW Rider

So even at 86% RH outside, you would gain significant drying of the inside air.

[/url]

With a HRV , but not with a bathroom fan when the exchange, is, already heated drier air going out for cold, more humid air coming in. I agree a simple bf will help in many situations but not for all.

[mark]

I'm with Ed on this (my weatherguy training), point to remember it's relative humidity.

Exhausting indoor moist air helps, all basically a HRV does is warm in the incoming air with the out going so you're not dumping (wasting) the heat outside. A bathroom just isn't a efficient way to do it.

[BMW Rider]

Originally Posted by hawk

With a HRV , but not with a bathroom fan when the exchange, is, already heated drier air going out for cold, more humid air coming in. I agree a simple bf will help in many situations but not for all.

The point I was making is that even though the outside air has a higher relative humidity, it actually has less moisture in it. The term relative humidity refers to the amount of moisture relative to the temperature of the air. Cold air can't hold as much moisture as warm air so even though it would seem to be more humid it actually is less so. Calgary can actually reach near to 100% relative humidy in very cold temperatures, but trust me, it is still really freaking dry.

It is irrelavant how you are making the air exchange, the colder outside air still has less moisture. The bathroom fan will work, its just that you'll be pumping all your expensive heat out with it.

[TheReefGeek]

Ok I went to the hardware store and got a bathroom fan, the tubing, and a 4" outside vent with a flap so that I dont lose heat when there is no air blowing.

Now, I found a humidistat, but that is to turn a humidifier on, I want the reverse. The only way I know to fix this is by installing a relay switch so that when the humidistat is on, the bathroom fan is off. Is there an easier way though?

I remember someone posted they have a bathroom fan with a humidistat, maybe they can chime in with how they did it?

[Delphinus]

You technically want a "dehumidistat" not a "humidistat" (they exist, the HRV's come with them).