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  1. #11
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    Jul 2010
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    Default Re: Air Circulation In Summer Without A/C?

    " I can't really afford air conditioning. "

    I just thought about an air cooler as a substitute to an a/c unit. A low cost, economical way to get relief from the heat.

    Search "air cooler" and learn about it and to see if you can benefit from one.

  2. #12
    Join Date
    Jan 2008
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    Default Re: Air Circulation In Summer Without A/C?

    I think DJ1 is referring to what we call a "swamp cooler" where air is drawn over water-dampened 'screens' to cool it. They work good but become less efficient as the ambient humidity rises- at about 85% they offer no benefit. Awnings, curtains, wide overhangs, balloon framing, plaster walls, and proper house siting were all used before A/C became common. "Whole House" fans are a good substitute but not being insulated they leak heat like crazy in the winter. What you want to do is to introduce cool air in and exhaust hot air out, and not have any dead spaces which can accumulate heated air. You don't need to move that air rapidly, only as completely as you can.

    I'm in an odd situation, living in an uninsulated cinderblock rental with metal casement windows set into the masonry. I cool things here with a box fan sitting in a window blowing inward from the shadiest (coolest) spot on one end, then let it exhaust through the window in the bath at the other end so the whole house sees airflow. It runs constantly. My calibrated and properly set up electronic thermometer says I'm 6F degrees cooler inside than out and the cost for electricity is about $6 a month. On the sweltering summer evenings a stand fan at the living room door assists the airflow. On the 100F degree days it's still a bit hot in here but I only miss my A/C a few days a year- I sure don't miss the power bills from back then! The thermal mass of the cinderblock delays the hottest day temp by a few hours so indoor temps are steady or still rising when the outside temp begins to fall but it's only a problem on the hottest days. A wood-frame house would react more quickly. Now if I could only get rid of the ambient humidity as easily and cheaply....

    Phil

  3. #13
    Join Date
    Nov 2009
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    Default Re: Air Circulation In Summer Without A/C?

    Thanks for the detailed reply. Unfortunately, there's something weird about this forum in that I -never- get an e-mail telling me when people reply... even though I have that activated in my Profile. Sorry for the slow reply.

    Quote Originally Posted by keith3267 View Post
    Do you have soffit vents? These are the little vents located under the eves of your house. Sometimes they are a perforated board like peg board.
    Yes. Soffit vents.

    Quote Originally Posted by keith3267 View Post
    Do you have ridge vents? This is along the ridgeline of the roof.

    Do you have gable vents and how big are they?

    You don't normally have both a ridge vent and gable vents, but you should have one of them along with the soffit vents. If you don't have enough ventilation for the attic, then this is the first place to start.
    I don't -think- we have either of these.

    Quote Originally Posted by keith3267 View Post
    Whole house fans have some advantages, but they do punch a big hole in your attic insulation and that needs to be addressed. The fan can be installed horizontally in the ceiling, but I do not like that idea very much because to get a decent sized fan up there, you cut through some joists and you have more difficulty with the insulation.

    You can mount a whole house fan in a gable vent and put a grill or louvers in the ceiling, but the fan will be drawing air from other sources as well as the house.

    The best way is to build a box in the ceiling and put the fan in that. Put the louvers below the box. In the winter, you can seal the louvers and put the insulation back in place.

    You can put the whole house fan or its louvers in the corner of the house that is furthest from the kitchen. Then open a window in the kitchen so that when the fan runs, air will be drawn from the kitchen, through the house and then exhausted.

    In the days before AC, people also put awnings over their east, west and south facing windows. Much of you heat gain is probably through the windows, even if they are low E or tinted. Awnings may not fit in your neighborhood, but they really do work. Solar screens can help also but they reduce the view.
    We have window shades on the west side.

    The 'attic' is really tiny. It's perhaps 2-1/2ft high. Now my neighbour has a split-level house and he has a big box fan he runs in an upstairs bedroom window to act as a 'whole-house fan' and he says it works well. I don't have an upstairs so that's not an option.

    From an installation POV, I think I could fairly easily cut a horizontal hole in the south side of the house in the attic if that's a reasonable way to do this. That wouldn't require busting up a ton of insulation or working in an easy-bake oven too small for a midget. Also, I know how to do the wiring so I can handle that.

    If the above is doable, my 'construction' concerns would be:
    a) how to do the 'flashing' or whatever you call it so that it's properly sealed against the elements and doesn't rot.

    b) I would want to know how to properly size the fan. IOW: I need to know how to determin the CFPM or whatever the unit of air flow is.

    Your thoughts

  4. #14
    Join Date
    Dec 2007
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    Tennessee
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    Default Re: Air Circulation In Summer Without A/C?

    The fan at the south end, is that to vent the attic or the house. It won't vent the house very well because it will draw air up through the soffit vents instead of the house. But it would vent the attic quite well.

    For venting the attic, you could have turbine vents installed in the roof. These are wind powered and as the spin, they draw hot air out of the attic. They allow some convection venting when the wind isn't blowing, but not as much.

    Solar powered vents are available. Again they mount to the roof so you don't have to get in the attic to install them, and they don't need any wiring. I suspect that they aren't very powerful though, solar panels don't generate very much power.

    What kind of shape is your roof in? If you will be needing a new roof shortly, look into options like a metal roof. Light colors can reduce your attic temperatures.

  5. #15
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    Aug 2007
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    Maryland
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    Default Re: Air Circulation In Summer Without A/C?

    Quote Originally Posted by suntower View Post
    Thanks. Those are good ideas.

    We have shades on most of the windows. I guess I neglected to mention that the fancy slider windows we have cannot easily accommodate box fans (or any other kind for that matter).
    Don't forget there are many fans that come with pedestals that allow the fan to be at window height. Even some big box fans come with frames that get it off the ground.

  6. #16
    Join Date
    Nov 2009
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    Default Re: Air Circulation In Summer Without A/C?

    ARGGGGGGH!!!!!!!!!!

    This STUPID forum software won't let me upload an illustration to show the air flow. DRIVES ME NUTS! NUTS! NUTS!

    (Sorry... cleansing breath. I used to write this sort of software and a piccie would make this about 1,000% simpler.)

    So... I've been doing some 'research' and apparently the 'web consensus' is that an attic fan is more for people in HOT climates (I'm in Seattle, not so hot. ). So a whole house fan is a better choice. Correct?

    I read some guides on CFPM. But they also stress that you need to have enough vents. I only have soffits that run the length of the east and west side of the house. (They are like a complete 'trough' under the eaves.) There are no vents on the north or south. I wonder if this is enough air flow.

    It sounds like a whole house fan may be a job for a professional?

  7. #17
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    Tennessee
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    Default Re: Air Circulation In Summer Without A/C?

    You can post pictures to a service like photobucket and then post the link here.

    If you have gable vents, they would be louvers under the eve at the top of the gable.



    A ridge vent would look like a raised section of shingles along the ridge of the roof. They usually go to within about two feet of each end of the roof. I don't have a picture but this web site should help.

    http://www.gaf.com/Roofing/Residential/Products.

    If you want to try a fan, start with a window fan available at hardware, home and department stores, even WalMart carries them. Put it in a window located at the farthest end of the house from the coolest room. Open a window just a little in the coolest room so that air is drawn in there, pulled through the house and out the window at the opposite end.

    This is not a true whole house fan but it might be enough. Because of your limited attic height that I assume is due to a low pitched roof, your options are really limited. A whole house fan would have to be installed in a ceiling near the center of your house and several windows would have to be open all day. Couple that with the loss of heat in the winter, you may not like this option in the long run.

    If you have a very low pitch roof as I suspect, a ridge vent sill not work well for you because it is harder to keep rain out on a low pitch roof. That also limits other types of rood mounted fans for the same reason. My suggestion is to first install a gable vent at each end of your house and see how that helps. If it isn't enough, then install a powered fan in one gable vent. You can even find a solar powered gable fan but again, I'm not sure that they are powerful enough.

    You do not have to be in a hot climate to benefit from attic ventilation, in fact you may benefit more in your climate. You get a lot of solar gain in your attic but in your climate, the air drawn in will be a lot cooler. Hot climates end up drawing in hot air, sometimes not much cooler than the attic air. But every little bit helps. BTW, an additional benefit of the gable vents will be to keep your attic insulation dryer so it will work more efficiently. Wet insulation does not insulate as well, same as wet clothing, and in your area, I suspect you are familiar with wet clothing from time to time.

  8. #18
    Join Date
    Nov 2009
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    73

    Default Re: Air Circulation In Summer Without A/C?

    Thanks for the generous reply,

    Quote Originally Posted by keith3267 View Post
    If you have gable vents, they would be louvers under the eve at the top of the gable.

    No gable vents or ridge vents. Just soffits.

    Quote Originally Posted by keith3267 View Post
    If you want to try a fan, start with a window fan available at hardware, home and department stores, even WalMart carries them. Put it in a window located at the farthest end of the house from the coolest room. Open a window just a little in the coolest room so that air is drawn in there, pulled through the house and out the window at the opposite end.
    The problem is that we have these odd 3-layer sliding windows. Any standard box fan (or for that matter window air conditioner) won't fit. Some people get desperate an make these horrible 'ghetto' looking cardboard adapters to use one of those one-room porta-air-conditioners.

    Quote Originally Posted by keith3267 View Post
    This is not a true whole house fan but it might be enough. Because of your limited attic height that I assume is due to a low pitched roof, your options are really limited. A whole house fan would have to be installed in a ceiling near the center of your house and several windows would have to be open all day. Couple that with the loss of heat in the winter, you may not like this option in the long run.

    If you have a very low pitch roof as I suspect, a ridge vent sill not work well for you because it is harder to keep rain out on a low pitch roof. That also limits other types of rood mounted fans for the same reason. My suggestion is to first install a gable vent at each end of your house and see how that helps. If it isn't enough, then install a powered fan in one gable vent. You can even find a solar powered gable fan but again, I'm not sure that they are powerful enough.

    You do not have to be in a hot climate to benefit from attic ventilation, in fact you may benefit more in your climate. You get a lot of solar gain in your attic but in your climate, the air drawn in will be a lot cooler. Hot climates end up drawing in hot air, sometimes not much cooler than the attic air. But every little bit helps. BTW, an additional benefit of the gable vents will be to keep your attic insulation dryer so it will work more efficiently. Wet insulation does not insulate as well, same as wet clothing, and in your area, I suspect you are familiar with wet clothing from time to time.
    This is very interesting advice. I definitely have a low pitch roof. None of the roofs like mine in the neighbourhood seem to have gable or ridge vents. Other than just being cheap 70's construction, there must've been a rationale I would think.

    Maybe the house cooling was OK when it was built, but when they added the super-insulation (when they built the airport) they neglected to add better venting.

    Now that you've given me some information on how this all works, I'm going to start asking the locals.

    Thanks A Million.

  9. #19
    Join Date
    Jan 2008
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    Default Re: Air Circulation In Summer Without A/C?

    I'll disagree with Keith as to the placement and airflow of the window fan, and here's why. Done as he suggests, you create a 'vacuum' towards the fan, and every leak in the envelope reduces that vacuum and the efficiency of the airflow. It also allows dust to be drawn inside from those leaks. By reversing the concept and pushing the cool air in, you still have the same envelope leaks but they have less effect on the efficiency of that airflow (positive pressure still exists) and you're pushing any dust out through the leaks. In any open-ended air-moving system pressure will be more effective than a vacuum.

    I keep a box fan on the truck for work, and there's a small rope tied to the top handle so I can figure out some way of hanging it in almost any window on the inside. If I want more effective ventilation from it I mask around it with cardboard and tape. "Window Fans" made with sheet-metal enclosures used to be made and don't look too bad for a 'permanent' installation; spray paint gives you whatever color you like to blend in with the decor. Alternately you can make something similar (even out of wood) which works with your box fan, again painting to match. With the fan inside the screen it will hardly be noticed outside of that room. The better the fan is sealed into the opening the better it will work. With your attic as small as it is I kind of doubt that it's building much heat but if you can ventilate and insulate it better do so- every little bit will help.

    Phil

  10. #20
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    Dec 2007
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    Tennessee
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    Default Re: Air Circulation In Summer Without A/C?

    Mastercarpentry makes a good point about the dust, but it is only valid if the window fan has an air filter on the outside of it. His point also applies to a whole house fan.

    There are low cost window fans, not box fans but window fans that fit into an opening only 10 inches or less in height. In fact I have one that uses a squirrel cage type fan that is only 5" tall, has a filter and can push or pull air. This one was a little pricier (about $30) than the typical twin 8" fans commonly sold for windows. It also has a built in thermostat so that also ran the price up a little.

    If one fan helps in either configuration but you need a little more, you could get two, one blowing in at the kitchen with a filter and one exhausting at the other end of the house. This would make a wind tunnel and with less vacuum, it would not draw in the dust as much.

    Honestly though, I would start with good gable vents at each end and see how that works. One recommendation though, get some good 1/4" hardware cloth to reinforce the screen. Birds will sometimes push in the screen or make a hole in it and then nest in your attic. The simplest solution is often the best.

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