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Old 11-14-2012, 12:11 PM
 
Location: Sunrise
10,865 posts, read 16,935,191 times
Reputation: 9084

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The only way it would be better is if it was a longer path from the attic access panel to the attic exhaust fan. Moving the panel to the billiards room would result in a little more efficiency. But there's almost no room up there in that area.

And I'm not going to punch a hole in the drywall, just to get what would likely be a few extra degrees of cooling.


It's not a perfect system -- the house was designed for an efficient HVAC system. Going with swamp coolers takes some extra fan power that wouldn't be needed in a house in Phoenix. But I'll take my $90 summer power bills and 80f house. That's about as good as I can do without knocking out walls.
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Old 11-14-2012, 01:00 PM
 
Location: Sunrise
10,865 posts, read 16,935,191 times
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Quote:
Originally Posted by lvoc View Post
I wonder if it is practical to swamp cool the attic of a conventional house in the high heat? Be reasonably easy to do and you could keep the wet hardware to the exterior of the house.
I don't think it's practical, considering how well simple powered ventilation works. If you can keep the attic at around the same temperature as the outside air, that's really all you need.

When we moved in, the attic just had soffits. That's it. Nothing else. I can't understand why that is allowable under building code. Maybe it isn't.

And it was basically a clay oven up there. You could put your hand on the upstairs ceilings and FEEL the heat coming down from above. Before our next summer, we installed the attic ventilation and it made a measurable difference. More electricity savings than the insulation that we added the following year.

The main thing about a thermostat-controlled fan in the attic is that when the sun goes down, the temperature drops significantly in a big hurry, even in the summer when it doesn't get much below 90f. The fan immediately evacuates all that leftover hot air in the attic. That way, you begin and end each day with a cool attic. Without the fan, the attic was just cooling down, just as the sun was rising to start the process again.

Put a fan in your north or east gable. Preferably north. Attach it to a thermostat and set it for 95f. That'll knock 15-20% off your summer cooling bills. Insulation will knock off an additional 5-10%. LED lightbulbs from Costco will reduce your year round power bills 5-20%. It's just a question of priorities.

With what we save, we can afford to take an extra week off work and go someplace nice. I'd rather do that than write big checks to NVenergy.
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Old 11-14-2012, 01:26 PM
 
12,973 posts, read 15,733,711 times
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Quote:
Originally Posted by ScoopLV View Post
I don't think it's practical, considering how well simple powered ventilation works. If you can keep the attic at around the same temperature as the outside air, that's really all you need.

When we moved in, the attic just had soffits. That's it. Nothing else. I can't understand why that is allowable under building code. Maybe it isn't.

And it was basically a clay oven up there. You could put your hand on the upstairs ceilings and FEEL the heat coming down from above. Before our next summer, we installed the attic ventilation and it made a measurable difference. More electricity savings than the insulation that we added the following year.

The main thing about a thermostat-controlled fan in the attic is that when the sun goes down, the temperature drops significantly in a big hurry, even in the summer when it doesn't get much below 90f. The fan immediately evacuates all that leftover hot air in the attic. That way, you begin and end each day with a cool attic. Without the fan, the attic was just cooling down, just as the sun was rising to start the process again.

Put a fan in your north or east gable. Preferably north. Attach it to a thermostat and set it for 95f. That'll knock 15-20% off your summer cooling bills. Insulation will knock off an additional 5-10%. LED lightbulbs from Costco will reduce your year round power bills 5-20%. It's just a question of priorities.

With what we save, we can afford to take an extra week off work and go someplace nice. I'd rather do that than write big checks to NVenergy.
We have large thermal controlled fans in north and west gables. East is not accessible.

Presently evaluating another dump of insulation into the attic. Already about a foot deep. Will consider blowing the walls next time we externally paint. Some thermal images indicate that we may have settled enough that half the wall is uninsulated.
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Old 11-14-2012, 01:46 PM
 
Location: Sunrise
10,865 posts, read 16,935,191 times
Reputation: 9084
Since the prevailing winds are from the South, Southwest and West, I don't see what the west-facing fan is doing for you.

I would temporarily cut the power to the west facing fan and see if that makes any difference in your bills. Soffits and a single fan in the north side of the house is the best overall solution. Our summer winds are almost never from the north. And during the winter when they often are, the fan isn't running anyway. Our single fan is on the north gable, and it is all we need.

I think you might actually save a little in power by shutting down the west fan. No way to tell without trying, though.
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Old 11-14-2012, 05:11 PM
 
12,973 posts, read 15,733,711 times
Reputation: 5478
Quote:
Originally Posted by ScoopLV View Post
Since the prevailing winds are from the South, Southwest and West, I don't see what the west-facing fan is doing for you.

I would temporarily cut the power to the west facing fan and see if that makes any difference in your bills. Soffits and a single fan in the north side of the house is the best overall solution. Our summer winds are almost never from the north. And during the winter when they often are, the fan isn't running anyway. Our single fan is on the north gable, and it is all we need.

I think you might actually save a little in power by shutting down the west fan. No way to tell without trying, though.
Remember I am up against the western Mountains...so it is virtually impossible for me to have a west wind.

I will see if I can work a way to do it. Maybe put an X10 module or something up there. Remember I am now no longer able to safely walk on rafters so I will have to get someone to do it.
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Old 11-14-2012, 06:19 PM
 
Location: Pahrump, NV
2,825 posts, read 4,470,757 times
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we built a "cat walk" in our attic, so we wouldn't have to walk on the rafters.
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Old 11-14-2012, 06:24 PM
 
12,973 posts, read 15,733,711 times
Reputation: 5478
Quote:
Originally Posted by cre8lite View Post
we built a "cat walk" in our attic, so we wouldn't have to walk on the rafters.
My balance and lower legs are defective. It is impractical to finish the attic without vast new initiatives on insulation and such. You don't want to compress the insulation by laying flooring over it. I suppose you could insulate the roof or add a reflecting layer...but that is going to a lot of trouble to minimize old fart disease.

Plus the unpleasant three minute climb up the fold down stairs with the Admiral screaming at me that only a really dumb old dude would even consider going up there.
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Old 11-15-2012, 01:28 AM
 
Location: Sunrise
10,865 posts, read 16,935,191 times
Reputation: 9084
Quote:
Originally Posted by lvoc View Post
Remember I am up against the western Mountains...so it is virtually impossible for me to have a west wind.

I will see if I can work a way to do it. Maybe put an X10 module or something up there. Remember I am now no longer able to safely walk on rafters so I will have to get someone to do it.
Well, I know that you're a computer guy, so I'll put it this way:

Imagine you have a computer case with two fans, both blowing air out from the case. That isn't very efficient. The fans are effectively fighting each other.

A better solution would be to have one fan blowing in, and one blowing out. Drastically higher airflow that way. Since you're on the extreme west end of town, you've got shade during the time of day that we're still cursing the sun here on the east side.

If it was my house, I'd reverse the west fan so it blows IN to the house, and leave the north one blowing out. That would more than double your airflow, and you'd get the coolest air possible circulating. If the north fan is stronger than the west fan, then the soffits around the perimeter pick up the slack for good airflow throughout the attic system.

You'd have to replace the louvered vent that is likely in the west gable (it's designed for airflow going the opposite direction). But I'm sure you can see the benefit.

Or just shut the west fan off and let the north fan handle the load. I'll bet that would be just as effective and save you a few amps in ventilation.

I'm sure you know some spry whippersnapper who can give it a try in the spring. (No need to do anything in November, after all.)
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