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Old 12-07-11, 06:32 PM   #10
Xringer
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My attic peak heat sensor is in place. It's showing 48.8F, my IR pistol shot up there said 47.8F,
my hardwired outdoor sensor (2' off the ground) says 45.1F and the weather guy down the road says 44.3F.?.

It's 70F in the house and it's been raining lightly all day. Yeah, there is some heat leaking up into the attic..

But, I wonder if a lot of it is coming up the basement stairs,
and finding a way into the attic, via the pull-down attic stairs??

The basement & it's stairs are closed off (by a door) from the rest of the house.
So some of the slab heat (50 to 60F) could very well be finding it's way to the attic..


"How much of this heat is going to be lost when feeding outside the house, down from the attic and into the back of the ODU? "


That's going to depend on the insulation around the duct-work.
But, if the air that feeds down is 10, 15 or 40 degrees warmer
than the normal outdoor air, it's going to help efficiency.

During a sunny morning, between about 8AM & 11AM,
the outdoor temperature starts climbing at a good rate.

My guess is, the temperature climb inside the attic is going to lag
behind (outdoor temps) at first, but then the attic will become warmer.
That's the fan ON signal. Warm air forced down to the ODU should
reduce the amount of watts needed to keep the house warm.
(At the same time, sun coming in the windows will be doing the same thing).

I think this scheme would likely work best when the air temp at ground level
was down near the low limit of the ASHP.
If it was around 10 deg F, I'm pretty sure my Sanyo wouldn't mind a shot
of nice 25 deg air coming in..

The Sanyo monitoring system that I'm trying to get running would be very
useful in controlling this kind of attic heat scavenger.

http://ecorenovator.org/forum/applia...ontroller.html

If I can make the CAI board monitor the power (watts) being used by each Sanyo,
factoring in the temperature of the refrigerant, going into and coming out
of the ODU, along with the indoor and outdoor air temps..
It might be possible to come up with some kind of real-time COP data.

I want to use this COP number, to compare the performance of each unit.
Comparing one against the other. If one Sanyo starts working poorly, it should be quickly apparent.

Having a real-time COP displayed on my tablet, might be very useful
for performing little experiments..
Like going outside with a 1200 watt hair drier (4094 BTU) and shooting
some hot air in back of the ODUs..
The effect that hair drier had on the COP display, might tell me if a project
building an attic heat scavenger might be worth the effort...
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