An economizer will often cool a place with a heat load when the outside temp is cool. For extrremely high heat loads during very cold outdoor conditions a unit must also be set up to run in cold weather, head press controls, etc. Otherwise and econo will not only save money on cooling but cool a place with a standard unit not equipped for winter run applications. Aw, hell, something like that.
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Hey cockroach, don't bug me!

VT;

The filters that come on an economizer intake are the aluminum type filter media. Since outdoor air is usually less dusty/dirty than indoor air, and especially on rooftops (since heavier particles have already precipitated out) the filters do not get very dirty very fast. Also, the slanted design of the economizer intake, which keeps rain out, means the filter's dirty side is pointing down, allowing a certain amount of off-cycle self cleaning. (The heavier dirt falls back out)

I've seen 15 year old economizer filters that had never been cleaned!

The more thought I give it, the less inclined I am to believe an economizer will ever pay for itself in a residential application.

P.S. Dice is talking about a large computer room, where the heat generated is too great to be removed by a fixed volume of outdoor air, and mechanical cooling will be necessary. These units have specially designed features that allow them to run in low ambient conditions.
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There are no stupid questions. . .just a lot of inquisitive idiots.

This is what I am talking about when I say I can use the outdoor air for about 6 months:



Graph starts at about 11AM yesterday, March 12th.

28C is 82.4F
8C is 46.4F

As you can see, the outdoor air gets significantly colder than indoor at about 5PM, provided the A/C didn't run during the day, but that's OK with me since this is just about when I get home. So if I want to cool the indoors to 24C (75F), I can start doing so immediately by opening the outdoors intake, and have good chances getting there by about 7:30-8PM, provided I can supply enough airflow.

But it's not gonna happen if I wait until the outside temperature gets to 55F That's 12.7C, and it's already midnight, and the indoor aid is cool enough already.
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--vt

VT; it looks like you have about 4 hours of usable freecooling available but thats just for this time of year. What would be more valuable is a graph for July and August.If you can wait to do the install and with the type of info you're collecting,you'll be able to do an acurate cost comparison of free cooling versus mechanical cooling.If you can't wait, maybe design so economiser could be an add on?BTW,are you sure you ain't a Canuck? all that info in degrees C sure looks familiar.
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I love my job, but paydays Thursday

rich pickering:

I've started measurements back in early September, and there was a sizable period when I could use something like this (if you're interested, there's a link to the archive on the first page). July and August - impossible; if the night temperature in September was barely dropping to 75F, I can imagine what it was like in the summer. I'm yet to see how usable this setup is in the spring - so far, looks good.

As for me being a Canuck, first of all, I've had to look up the word in the dictionary, and no, I am not, and second, damn, you've just complimented my English, 'cause it is not even my second language, it is third My native is Russian. Not that I'm Russian, though
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--vt

Vt

How bout opening a window.

Man you Engineers are tight. You spend all this time,energy and money on trying to save money. Like my friend in Texas said. People will go to the ball park and spend a $100 on tickets, food and beer and watch a bozo that is paid $3,000,000 scratch his balls and then talk about what a great time they had.

how bout working on a really important project.Like free cable TV. I never understood why we had to pay to watch advertisements? How stupid!
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Today we did what we had to do. They counted on America to be passive. They counted wrong -- Ronald Reagan

Man James, I would have thought you would get it. Engineers will spend $1000 to cheat the power company out of a dime, then spend another $1000 telling everybody else in the world how to do it.

VT is my buddy, even if he does have this cock-a-mamie notion about the economiser, just because he is out to do the job right, and save money on his power bill.

So, watch the guy scratch his balls if you want, but do it somewhere else.
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There are no stupid questions. . .just a lot of inquisitive idiots.

I'm just standing by, enjoying all the good info on what economizers do and how they work (I had always thought myself that there must be some situations where cooler outside air can be used to save on air conditioning, now I know it's done and the name it has...). Bama's explanations are always technically interesting and fun, and my prime reason for hanging around this forum. Keep 'em coming.
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If you don't know what you're doing, do it neatly