[Buzz123]

What should it cost? Is it the best way to go? Any good companies that won't rip you off? Can they do it without making big holes?

This house has the Manabloc manifold plumbing using PEX tubing. It goes through the ceiling craw space, and I'm sure they put it on top of instead of under the insulation. So in winter it takes forever to get hot water, and in summer you can't get cold water.

[ScoopLV]

Originally Posted by Buzz123

What should it cost? Is it the best way to go? Any good companies that won't rip you off? Can they do it without making big holes?

This house has the Manabloc manifold plumbing using PEX tubing. It goes through the ceiling craw space, and I'm sure they put it on top of instead of under the insulation. So in winter it takes forever to get hot water, and in summer you can't get cold water.

You can buy the insulation at one of the big box home stores, and they will throw in the rental of the blower. Or you can go with one of the insulation companies. Price depends on the square footage of the house. In our case, I believe it was $800. (I went with the insulation company that guaranteed we'd get the energy tax credits. So our bottom line cost was close to zero. But I don't know if those tax credits are still available.)

Attic insulation did a great deal for our monthly bills. But powered attic ventilation did far more -- at least in the summer when it really matters. But both of them are financial "no brainers." They pay for themselves in less than one year.

My one concern would be burying your plumbing under insulation. If you ever have any problems with the plumbing in your attic, it will make it that much harder to fix. You can install a pump that circulates the hot water through your house, so you always get hot water in the winter. Attic ventilation will go a long way towards getting colder water in the summer.

Solar screens was the number one "bang for the buck" energy saver for us. Attic ventilation was number two. Attic insulation was number three.

Attic ventilation is also the reason our evaporative coolers are so effective. The final exit point for the moist air that enters the house is through the attic (we leave the access panel open all summer -- we only just shut it this week). What remains of the moist air exhausts through the attic, where the moisture evaporates and cools the attic to below ambient temperature. When it's 115f outside, our attic is only 100f. That pays major dividends -- the house is much slower to warm up, and much quicker to cool down. (On the rare days that we run air conditioning, we close the attic. But even then, the fan is helping immensely. Far more overall savings than what the little fan draws in electricity.)

Install a fan this spring, if you don't have one already. The solar fans are too anemic. Hard wire it for maximum cubic feet per minute (CFM). Buy the highest CFM fan you can lay your hands on. And place it in the north side of your attic if possible, or east as a secondary option. Our prevailing winds are from the south -- so a fan cannot win the battle against mother nature.

[BBMW]

I'm missing something here.

First, if the air going into your attic is moist, the water has already evaporated into it. You're not getting any evaporative cooling up there, unless you are adding liquid water somewhere.

Second, if your attic temperature is less than outside ambient, you're actively cooling your attic. This means whatever you using to cool your living space (since you say it isn't AC, maybe swap coolers?), is also cooling your attic. Since you don't live in your attic, you're wasting effort somewhere. You'd be better off sealing the attic from the living space and using that cooling there. The attic blower is a good idea, to flush out the air that gets heated by solar gain through the roof. However, the best case scenario is that you get the attic down to outside ambient temperature. Anything below that is a signal of a problem.

Do the ceramic roof tiles used in vegas need to be vented behind them, like fiberglass/asphalt shingles? If not, I'd consider putting a layer of foil backing (facing up/out) against the roof sheathing, and spray foaming over that (if the foam will deal with the heat Vegas.) That would keep a lot of the solar gain out of the attic in the first place, then the fan can get rid of most of the rest, and the ceiling insulation can keep the cool air from the living space in.

Originally Posted by ScoopLV

<snip>

Attic ventilation is also the reason our evaporative coolers are so effective. The final exit point for the moist air that enters the house is through the attic (we leave the access panel open all summer -- we only just shut it this week). What remains of the moist air exhausts through the attic, where the moisture evaporates and cools the attic to below ambient temperature. When it's 115f outside, our attic is only 100f. That pays major dividends -- the house is much slower to warm up, and much quicker to cool down. (On the rare days that we run air conditioning, we close the attic. But even then, the fan is helping immensely. Far more overall savings than what the little fan draws in electricity.)

<snip>

[ScoopLV]

Originally Posted by BBMW

I'm missing something here.

Swamp coolers don't work like HVAC. They require open windows and airflow. The moist air is blown in at one end of the house, windows are opened at the other end, moist and dry air mingles to evaporate moisture, and that removes heat from the house.

Since it isn't 100% efficient, a second stage exhaust system takes what's left of the moist air, and moves it into the attic, where most of the rest of the moisture evaporates, removing heat from the attic.

[SportyandMisty]

Red rock insulation . com

They are very competent.

[MediocreButArrogant]

Originally Posted by ScoopLV

Swamp coolers don't work like HVAC. They require open windows and airflow. The moist air is blown in at one end of the house, windows are opened at the other end, moist and dry air mingles to evaporate moisture, and that removes heat from the house.

Since it isn't 100% efficient, a second stage exhaust system takes what's left of the moist air, and moves it into the attic, where most of the rest of the moisture evaporates, removing heat from the attic.

That's not how they work. They cool when the water in the pad absorbs the latent heat from the outside air and evaporates.

BBMW was right.

[ScoopLV]

But the moist air needs to go somewhere. You can't just shut the house down tight as a drum and expect the system to work. Eventually, all that moisture just piles up.

I have tested many configurations using a thermometer and hygrometer. (I have a little weather station from Oregon Scientific that I bought for this.) The best configuration for the swamp coolers is attic panel open, attic fan circulating, and at least one open window, preferably in the north side of the house.

In addition, if you stand anywhere near the open window, you can feel the secondary evaporation happening. It is often 10 degrees cooler around the open window. I have measured this. The difference between attic panel open and closed is roughly 15 degrees. Again, a measurable difference.

This is where Arizona houses have it right -- they were designed for this kind of cooling system. The cooler is on the roof, blows the air down to the living areas, which then vent out open windows. Air flow is the key. Intelligent air flow, designed into the house from the get-go. We don't have that kind of design, and have cobbled together the best system that we can.

So we also keep an eye on the weather station in the summer and watch the dew point.

http://www.azcentral.com/business/ar...omes-1001.html

[BBMW]

Scoop is using an open circuit system, so the moist air does need to be vented out. I'm still skeptical of this "secondary evaporation" effect he talks about. Unless there's liquid water, there won't be any evaporation. There are closed circuit systems that don't actually bring the moist air into the cooled space. That would be different.

What would be interesting would be to use an open circuit system that exhausted the output airstream through a heat recovery ventilator, and fed the cooler dry air coming out of that as the input of the swamp cooler.

[ScoopLV]

Originally Posted by BBMW

Scoop is using an open circuit system, so the moist air does need to be vented out. I'm still skeptical of this "secondary evaporation" effect he talks about. Unless there's liquid water, there won't be any evaporation. There are closed circuit systems that don't actually bring the moist air into the cooled space. That would be different.

What would be interesting would be to use an open circuit system that exhausted the output airstream through a heat recovery ventilator, and fed the cooler dry air coming out of that as the input of the swamp cooler.

If you'd like, you are welcome to visit next summer and see for yourself. You can literally feel the difference. And the humidity drops and the temperature drops measurably. This is something I've been measuring and tweaking for the past five years.

There doesn't need to be liquid water for evaporation to happen -- just a difference in the moisture content. The two systems will work toward equilibrium, wicking heat as necessary.

[lvoc]

The physics are one thing the practical another. Scoops system basically uses the attic as one of several paths for air flow in the house and in the process keeps the attic cool helping the overall effort.

It is actually a pretty good idea I would think. Somewhat the reverse of the standard AZ system but it does help particularly with high flow fans in the attic.

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.