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Xringer · 07-14-12, 12:18 PM

I have one of those cheapo remote temperature sensors hanging up near the peak of my attic.
I've seen it hit 120F recently up there, when the outdoor temp was in the high 80s, low 90s.

I've checked out my old attic fan and it still works. Not sure how much power it uses,
but I'm sure that it's not real efficient. It's on the east wall.

When we aren't using the house AC, we keep the attic stair (pull-down)
open a few inches to allow the house air to be pulled up into the attic.
Acts a little like one of those 'Whole House' fans.
But, when we are using AC cooling (like today), most of the air input into
the attic comes from the peak vent on the west wall.

It starts up just a little above 100F and tends to stay on until late in the afternoon.
I don't like the hysteresis of it's sensor, since it stays on for so long.
I think the attic temp drops down to around 90F before the fan shuts off..

I'm trying a Timer experiment now. AC power goes off for 30 minutes and
comes back on for 30 minutes, all day long.
So, during the heat of the day, it's going to running on a 50% duty cycle.
Should save us 50% on fan power use..

07-14-12, 12:18 PM	#8
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I have one of those cheapo remote temperature sensors hanging up near the peak of my attic. I've seen it hit 120F recently up there, when the outdoor temp was in the high 80s, low 90s. I've checked out my old attic fan and it still works. Not sure how much power it uses, but I'm sure that it's not real efficient. It's on the east wall. When we aren't using the house AC, we keep the attic stair (pull-down) open a few inches to allow the house air to be pulled up into the attic. Acts a little like one of those 'Whole House' fans. But, when we are using AC cooling (like today), most of the air input into the attic comes from the peak vent on the west wall. It starts up just a little above 100F and tends to stay on until late in the afternoon. I don't like the hysteresis of it's sensor, since it stays on for so long. I think the attic temp drops down to around 90F before the fan shuts off.. I'm trying a Timer experiment now. AC power goes off for 30 minutes and comes back on for 30 minutes, all day long. So, during the heat of the day, it's going to running on a 50% duty cycle. Should save us 50% on fan power use.. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..