This is the fourth article in the series. Unlike the
three previous articles it was written specifically for the Forum and will be modified later for inclusion in the family instruction book or FAQ.
As always all comments and suggestions are welcome.
HOW THE ATTIC FAN WORKS AND WHY
July 3, 2007
Oldtimer
A Supplement To The Household FAQ Book
- Section "VIII"-Oil Burner & Thermostats
- Section "IX"-Electrical System & X-10 Controls
- Section "XIII"-Seasonal Maintenance
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While we don't actually live on the beach we live right on the Connecticut shore which provides us with some beneficial weather patterns. On the average it is 10 degrees cooler in the summer and 10 degrees warmer in the winter then it is inland. Also, because of the differential in the temperature between Long Island Sound and the inland land masses we get prevailing on or off shore breezes most of the time. The direction depends on the time of day.
To take extra advantage of this, in 1991, the first full summer we spent in our present home, I installed a large fan in the ceiling of the upstairs hallway to exhaust air into the attic and out the two vents at each end. This fan included the usual louvers that opened with the force of the air flow from the fan. Several years later one of our grown daughters pointed out to us that in the summer we should keep the louvers open all the time even if the fan wasn't running to allow natural ventilation to occur. It worked very well and we've done it ever since. In the winter the louvers are shut and fiberglass insulating bats in plastic bags are put over the fan in the attic to eliminate drafts and insulate that part of the ceiling.
Although we had already started to convert the house lights to X10 before the fan was installed there was no computer control for them at the time so I chose to use traditional fan controls. These included a summer/winter switch, an electro- mechanical timer and an industrial low limit thermostat installed in the attic along with a fan speed control and manual/timer switch in the upstairs hall near the fan. These worked OK but we ended up almost always operating the fan manually. The timer couldn't be left on if we were away with the windows closed and the residual heat from the roof overrode the air temperature so the thermostat never turned off the fan when it got too cool downstairs in the house.
The beginning of summer, 2007. I ripped out the old traditional attic fan control system and replaced it with X10 modules, X10 switches, a thermostat in the upstairs hall and AHP macros and timers. Below is a block diagram of the new system.
Click below to see more complete information. They're all PDF files so be sure to enlarge them in your browser or print them off in normal mode to get the best view.
(Landscape)
(Portrait)
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Here are some photos of the installation: