Thursday, August 20, 2009
Six summers in San Antonio with a whole house fan
Yes, I survived six summers in San Antonio with a whole house fan as my primary cooling.
A whole house fan is not an attic fan, though it exhausts into the attic. A whole house fan is usually mounted in the ceiling of a hallway. It is very powerful and draws outside air in through open windows and pushes it out through the attic. In doing so it makes the inside as cool as the outside and does the same for your attic.
In my leaky 1920's, clapboard with interior shiplap covered with thin drywall, the fan drew air not just through open windows but also through almost invisible and not so invisible gaps in the wood floors and through the holes around electrical outlets.
The house doesn't have a hallway so I mounted in toward the center of the house.
The fan worked great. San Antonio does actually get a little cooler at night and I slept much better with the gentle cooler breezes seeping and flowing through and heading up into my attic.
My house was very comfortable from bedtime until 10 am well into a typical June and even in August, it was comfortable until at least 9 am. It was much more comfortable than it would have been without the fan.
But, it was extremely noisy. Just the amount of air flowing through is loud but the fan itself makes quite a clamor. A belt drive whole house fan costs more than a direct drive model but the belt drive ones are supposed to be quieter. I had a direct drive one. To talk on the phone I often had to turn it off.
I also had to be sure to turn the fan off before the outside temperature started to rise. If I left it on all day, then the fan would bring all the hot outside air in. But if I turned it off at the correct time I would have a load of slightly cooler air inside to enjoy.
In my case part of the air was coming from beneath my house which was cooler than the outside air. Until about mid-June or July the air passing over the ground in my crawl space was slightly cooled by it. But eventually the air flowing over it warmed that ground too.
The renters of my old house with the whole house fan don't use it. Instead they run a window unit 24 hours a day. It much quieter and they probably have much less dusting to do but it costs them a lot more.
Today so many people try to get by with barely using their central air systems, but if I was trying to do that I would definitely install a whole house fan. I'd use a belt drive model to try to minimize the noise and I'd mount it in a hallway, not a room I intended to use. At bed time or a little earlier, I'd open up the windows and turn it on. In the morning I'd turn it off and shut the windows.
That would give my central air a fighting chance during the rest of the day or if I kept the AC off my inside would be at least as comfortable as the outside would be with a gentle breeze.
I lived for six years with a whole house fan and I'd do it again if we didn't have geothermal or if I found myself single and living in that 1920's house again.