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Thread: Evaporative Cooler Question

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    Default Evaporative Cooler Question

    I was thinking evaporative Cooler works like a Car Radiator System , but in reverse.

    In a car, the surrounding air is pushed through the radiator grill.
    As the air passes through , it absorbs heat from the radiator and the radiator therefore cools down.
    And I figure that the absolute minimum possible lowest temperature yhe radiator can drop to is that of the ambient air temperature.

    In a Home Cooler, air is passed through a radiator what is hooked up to the plumbing supply.
    The ambient air is passed through this radiator and is cooled down and supplied to the room where it is needed.

    I figure that the lowest possible temperature the cooled air can reach is the temperature of the water that is in the radiator.

    I don't wish to know the workings of evaporative coolers, but just wish to know if that last bit of figuring I done is correct.



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    No it doesn't work like a reversed radiator. Evaporative air-conditioners work on the principle of the heat necessary to cause evaporation of the water is drawn out of the air-stream that is then blown through out the house.

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    I found this in 'wikipedia'
    At 32 C (90 F) and 15% relative humidity, air may be cooled to nearly 16 C (61 F).
    The At 32 C (90 F) and 50% relative humidity, air may be cooled to about 24 C (75 F).
    At 40 C (104 F) and 15% relative humidity, air may be cooled to nearly 21 C (70 F).

    I have had evap coolers installed to 2 of my previous houses and these figures seem accurate, the drier the air the better the cooling effect, on realy humid days the water was turned off and the fact that moving (replacing) the inside air seemed to keep the house/s comfortable
    Brian
    Last edited by bop; 18-11-10 at 08:48 AM.

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    Hi mooee

    yes a car radiator would remove the heat from air as per your workings, but this is the principle of an air conditioner - cool fluid inside a heat exchanger...... hot air passing over the heat exchanger cooling the air removing humidity


    As ssrattus stated - the evaporative cooler uses the water flowing over surface area to remove the heat & increasing humidity, and as such evaporates water & needing water to be added.


    cheers


    f
    有段者

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    Ive had one in Melbourne it was excellent except on the few days it was humid.

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    My brother has evaporative and on hot days it just takes the edge off the heat and also increases humidity.

    I put a inverter cooler, never been happier, hot or cold.

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    Quote Originally Posted by Godzilla View Post
    My brother has evaporative and on hot days it just takes the edge off the heat and also increases humidity.

    I put a inverter cooler, never been happier, hot or cold.
    what brand godzilla & how long have you had it?
    woteva

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    As bop posted (ex wiki) the efficiency does reduce with humidity increases.
    We have had ours fitted for 8 years, and have found it great value for money.
    Here in the Southwest of W.A. there would be no more than a couple of days per summer where it did not make a great difference.

    Would I have one if I lived in a really humid climate? No way. Horses for courses.
    Make the decision based on local conditions, and keep in mind that if you live where the humidity is high for some of the summer, but 50% or below for a lot of summer, you could always use the evap most of the time and small (er) R/cycle for the bad days. You would still make considerable savings on power. Over time it would achieve pay-back and then savings.

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    I am familiar with Bonaire & Celair EAC's & have access to some manuals if required.

    "Southwest of W.A." where only the best people live!
    woteva

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    Quote Originally Posted by ptrott View Post
    Would I have one if I lived in a really humid climate? No way. Horses for courses.
    Make the decision based on local conditions, and keep in mind that if you live where the humidity is high for some of the summer, but 50% or below for a lot of summer, you could always use the evap most of the time and small (er) R/cycle for the bad days. You would still make considerable savings on power. Over time it would achieve pay-back and then savings.
    This is 100% spot on.

    The advantage of the EAC, in my case, is that it is ducted to all bedrooms, lounge, kitchen/dining room.

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    Quote Originally Posted by moeee View Post
    I figure that the lowest possible temperature the cooled air can reach is the temperature of the water that is in the radiator.

    I don't wish to know the workings of evaporative coolers, but just wish to know if that last bit of figuring I done is correct.
    As for the original question, that would be correct, eventually! A radiator used in this fashion would be inherently less efficient than a evaporative pad primarily as the water in a radiator is just that, 'in' the radiator. The water or whatever medium you are using needs to transfer heat twice to take effect, once to the radiator then once again to the air. With the evap pad the water is on the outside of the medium so tranfers directly to the air and creates the wind chill factor at the same time.

    And yes I agree the Sth West is the only place to be.......... but exactly where makes a big difference to what type of aircon you have.
    I am happy with evap where I am as I am off the coast where the humidity is less. As has been pointed out humidity plays a big part with the evap efficiency.

    As for make, well Bonaire are good if you can afford them but from an installers point of view and from 20 years looking at these things the Coolbreeze units are the best overall. Particularly on the coast where everything else corrodes.

    Cheers

    "Just my 2 cents worth (O thats right, we don't have 2 cents anymore)"

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    Have EAC in Melbourne. Works well most days, humidity the determining factor.
    Have been looking at putting in Security Vents which are a simple vent with flaps similar to the draft stoppers you can get for bathroom exhoust fans. Idea is the cool air exhausts to the roof cavity where it will then cools the roof cavity and exhausts out a whirly bird or tiles. You shut your windows and doors. (Shouldnt run fan at full speed)
    Have tried with my attic ladder door down and believe it helps.
    They are about $60-70 each, recommended 1 per 3 EAC vents

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    Quote Originally Posted by BShifty View Post
    Have EAC in Melbourne. Works well most days, humidity the determining factor.
    Have been looking at putting in Security Vents which are a simple vent with flaps similar to the draft stoppers you can get for bathroom exhoust fans. Idea is the cool air exhausts to the roof cavity where it will then cools the roof cavity and exhausts out a whirly bird or tiles. You shut your windows and doors. (Shouldnt run fan at full speed)
    Have tried with my attic ladder door down and believe it helps.
    They are about $60-70 each, recommended 1 per 3 EAC vents
    Bshifty

    I agree with what you said, and your thinking behind the vents, I normally put the fan on in the bathrooms if it gets very hot and the draftstoppers open venting into the roof, but would be interested seeing the Security Vents you mention, venting into the roof 1, cools the house down 2, cools the roof cavity, 3 cooler roof cavity means cooler house....double edged sword!....

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    rokkzz

    got you pm don't have a manual for a vf75, are you sure of the model number
    woteva

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    I was told evaporative coolers are not intended for coastal or humid areas as they actualy add moisture to the air where A/C removes the moisture.
    This why they are very popular in the Inland areas where the humidity is generaly much lower than the coastal strip.
    A neighbour had one installed here in the Central Tablelands and it worked well except his internal doors swelled and they wouldnt close.
    With A/C you need to keep the house closed or the running costs increase but with evaporative cooling, this isnt necassary.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Any info on those security vents, sounds like a good idea.

    My bother leaves his door to the garage open and the air vents through this.

    Cooling the roof space is brilliant, and with the gaps in the roofing the air would easily vent.
    Last edited by myf360f1; 12-02-11 at 05:13 PM.

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    Quote Originally Posted by omega99 View Post
    what brand godzilla & how long have you had it?
    Just saw your question, a few months late....

    Daiken inverter, second summer now, used it through last winter for heating too.

    It actually costs me less to heat the house in winter with this system than with my gas ducted heater.

    Summer its ice cold.

    Sorry for the late reply.

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    Evap Security Vents, check out
    Components Price Book Page 39


    And


    Hope this helps

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