bathroom skylight venting for cooling purposes
I am reposting this to the HVAC forum. Thanks for your help on this. Here goes:
(Originally posted by FMS13 on the Remodeling Forum):
Would top floor bathroom roof ventilation fan help or hurt AC efforts? I have a top floor bathroom with "sunroof" passive louvers type vent. Two glass window flaps are at the ceiling of the bathroom and then it goes out to the roof and has vent slats on the sides to allow ventilation. Problem is whenever I open the windows, dirt and leaves collect there and fall into the bathroom.
If I take out the vent slates and use a fan instead so that I don't get dirt and leaves in when I open the window - would this be good or bad for my central AC? One person says it will suck the cool air out of your house, and that the passive louver system is best. Another says closing the louvers and putting in a solar fan with a temp gauge to turn on and off to let out hot air will keep the house cool during the day when you turn down the AC.
So, which is the best to do? This is completely separate from the attic, which is just crawl space and insulated.
reply by worthy:
The purpose of the bathroom vent fan is to remove excessive humidity from the air to avoid rot and mould problems. Passive ventilation doesn't do the job. To avoid removing an excessive amount of conditioned air, you can put a timer on the fan; some controls allow for a choice of pre-programmed exhaust times, automatic operation when the room is occupied and even humidity sensing controls.
reply by homebound:
I know the OP, so let me clarify their situation.
The house is circa 1920 and the bathroom has a tall, louvered skylight (original) which extends upward roughly 4' above ceiling plane). The skylight is opened and closed by way of a pair of hinged glass panes that fold open (vertical) or closed (horizontal) near the ceiling. (The louvers are permanently open).
The OP's intention is to permanently close and seal the louvers (to prevent dust and leaves), replace/install a vent fan in the skylight, and use the vent fan for longer periods to vent and cool the house (instead of using the central AC all the time).
This house is a typical two-story townhome (row houses) in Washington DC which has a hot, humid summer season most of the time.
I will reserve my opinion at this time, but suggested that they post here to get other opinions. They have been told that installing a vent fan into the skylight on a thermostat is a good idea (much like an attic vent fan).