The intent of the attic vent fan is to vent the hot air which stacks up in the attic and transfers its heat to the rest of the house. In order for this to work, it must be able to draw enough fresh air from the outside to properly vent the hot air. It can do this with gable, soffit, and/or ridge vents. Otherwise it can actually depressurize the attic and pull up air from inside the house (which can make an air conditioner work overtime and draw fumes from things like gas water heaters).
There are two types of attic vent fans, those that are installed in the roof, and those which are installed in a gable end of the attic. Neither Dan nor I was too keen on cutting a hole in the roof, and since we have gable vents on all the gables we opted for a solar gable fan.
Installation was very easy.
|First step was to remove the old vent cover.|
|The fan was slightly wider than the vent opening, so a|
little cutting with the jig saw was all that was needed.
|Scraps filled the gaps and hardware cloth covers the fan so that things|
like bats, snakes, or squirrels can't move in. We still need a new vent cover.
|The solar panel went on top of the roof. Dan ran the cord through the|
opening that was already there for flood lights (which are disconnected).
This one came with a pre-installed thermostat so that the fan kicks on when the attic temperature reaches 85°F (29°C). It is easy to remove or replace with a programmable thermostat. The fan runs whenever the daylight is bright enough to power the fan (it doesn't necessarily need the sun). It picks up speed and vents fastest when the sun is overhead.
How well does it work? Last Tuesday was our hottest day so far this year.
|The top number is the outside temperature, bottom|
is inside (kitchen, warmest room in the house).
The high was 99°F (37°C) outside, while inside it was a "tolerable" 84°F (29°C). Some folks may argue the "tolerability" of 84° for an inside temperature, however, there is something to be said for acclimatization. We live in the southern United States, after all, and 99° is a typical summer temperature for us (and the price we pay for having such an early growing season). Dan and I spend a lot of time outdoors, so a 15 degree difference is most welcoming when we go inside. The other benefit is that going outside again isn't a wilting shock to one's system like it is with air conditioning ("hey, it doesn't feel so bad out here"). I'll also add that in the past I've found that to run the air conditioner when the temperatures are that high means it runs nonstop, and that the electric bill is then just as oppressive as the heat.
Of course we do all the common sense things to keep the house as cool as possible:
- vent hot air from the house at night with window fans (a whole house fan would do the best job and is on our someday list)
- close up in the morning when outside temperature matches inside temperature
- keep curtains drawn on sunny side of house
- use ceiling fans
- use a summer kitchen to keep cooking and canning heat and humidity out of the house (also the solar oven and grill)
I have to add that replacing the old windows with energy efficient ones and adding more wall insulation has helped. And I'm looking forward to being able to shade those west-facing windows someday.
The other thing we do is simply accept that summer is hot and winter is cold. That's just the way things are.