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  1. #14
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    Aug 2012
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    Iraq
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    Quote Originally Posted by skippedover View Post
    You're given some very high numbers with limited information. For example, saying 60C to 70C is meaningless until you define the location of those temps. Normally for such a discussion, we'd need to have some idea of the indoor dry and wet bulb temps as well as the OAT. For example, if the indoor dry bulb is 60C and the OAT is 50C, then I'd first recommend a large dose outdoor air be circulated to reduce the indoor temps. Other questions I'd have would be about line length. Are you doing long lines applications? Capacity can be lost when using long lines. Standard conditions are not with what you're dealing here so I'd suspect you may need to have an engineered system, rather than off the line residential of light commercial units.
    60C to 70C temp of ambient (outdoor)
    the long of pipe line is 5 m

  2. #15
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    Feb 2006
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    Phoenix,AZ
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    Quote Originally Posted by kefah View Post
    60C to 70C temp of ambient (outdoor)
    the long of pipe line is 5 m
    Get a portable SWAMP COOLER and place it's supply outlet next to the A/C. 158F is craZY HIGH.
    Serious, you need some type of pre-cooler!!

  3. #16
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    Feb 2009
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    Tallahassee, FL
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    Yes you need water source units.

  4. #17
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    Aug 2012
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    Quote Originally Posted by KB Cool View Post
    Get a portable SWAMP COOLER and place it's supply outlet next to the A/C. 158F is craZY HIGH.
    Serious, you need some type of pre-cooler!!
    can u explain more if u dont mind

  5. #18
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    Iraq
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    Quote Originally Posted by SBKold View Post
    Yes you need water source units.
    can u explain more if u dont mind

  6. #19
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    Feb 2006
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    Phoenix,AZ
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    Quote Originally Posted by kefah View Post
    can u explain more if u dont mind
    http://www.piec.com/precooler.htm

  7. #20
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    Feb 2006
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    Phoenix,AZ
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    And here's a quick low budget more harm than good in the long run fix.

    http://www.gogreenitems.com/Cool_N_S...m_p/cnss-1.htm

  8. #21
    Join Date
    Dec 2006
    Location
    Goodyear, AZ
    Posts
    197
    An R-22 has a critical point temperature of 205.6 degrees F and loses about 6% of capacity for every 10 degrees above 95 degrees OSA.

    An R-410A has a critical point temperature of 162.5 degrees F and loses about 7.5% of capacity for every 10 degrees above 95 degrees OSA.

    Both refrigerants lose about 2% of capacity on a condenser for every 1000 feet of rise in altitude.

    The performance of both R-22 and R-410A is influenced by condensing temperature – R410A is slightly more sensitive to condensing ambient temperature than is R-22 up to around 45C. Above this temperature (equivalent to a condensing temperature of around 60C) the refrigeration capacity of the R-410A system starts to fall off more rapidly. At this temperature the relative drop in capacity exhibited by R-410A systems is around 10% greater than that of an R-22 system.

    RDHolder
    shop.rdholder.com

  9. #22
    Join Date
    Jan 2005
    Location
    southeast
    Posts
    83
    kefah

    The reason your having problems with the new R-410A systems is due to the characteristics of the refrigerant and the outdoor temperatures your experiencing. R-410A is not designed for air cooled equipment at the temperatures you indicated.

    If we go back to the principles of refrigeration, the way we cool is to send a liquid refrigerant to a heat exchanger where it boils. The only way to boil a liquid is to add energy to it, in our case HEAT. As we remove the energy surrounding the coil to boil the refrigerant we cool the area. This energy is now trapped in the refrigerant vapor and we need to release the heat energy to return the refrigerant to a liquid state to be used again to absorb more energy. And this goes on over and over. Pretty simple process.

    In your case the problem is your outdoor temperature.

    In order to condense a refrigerant vapor we compress it to increase its temperature above the ambient surrounding the heat exchanger coil. With the temperature of the refrigerant climbing above the ambient air (normally 15- 25 degrees F) the heat naturally flows out of the vapor and condenses the refrigerant.

    I think in degree F so lets convert. 60C = 140F, 70C = 158F. Using this information, a system operating in a outdoor condition of 60C will need to condense between 155F to 165F depending on the equipment (remember condense 15-25 degrees above ambient), in a outdoor condition of 70C will need to condense between 173F to 183F depending on the equipment (remember condense 15-25 degrees above ambient) This would be considered normal for the conditions.

    The characteristics of R-410A are that it has what they call a Critical temperature of around 162F. This means that R-410A cant exist as a liquid above this temperature no matter what the pressure is, as a matter of fact it will be a vapor no matter what the pressure needs to be. If you look back at the condensing temps at your temperatures at 60C you MIGHT condense if the condensing unit is designed for a minimum rise above ambient. At 70C its NOT going to condense.

    The reason R-22 worked is the critical temperature is around 204F which would allow it be able to condense at the conditions above.

    I hope this helps to explain why your having problems with an air cooled R-410A system in your location.

    Good luck
    Coolinman

  10. #23
    Join Date
    Jul 2011
    Location
    East coast USA
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    955
    Quote Originally Posted by rdholder View Post
    An R-22 has a critical point temperature of 205.6 degrees F and loses about 6% of capacity for every 10 degrees above 95 degrees OSA.

    An R-410A has a critical point temperature of 162.5 degrees F and loses about 7.5% of capacity for every 10 degrees above 95 degrees OSA.

    Both refrigerants lose about 2% of capacity on a condenser for every 1000 feet of rise in altitude.

    The performance of both R-22 and R-410A is influenced by condensing temperature R410A is slightly more sensitive to condensing ambient temperature than is R-22 up to around 45C. Above this temperature (equivalent to a condensing temperature of around 60C) the refrigeration capacity of the R-410A system starts to fall off more rapidly. At this temperature the relative drop in capacity exhibited by R-410A systems is around 10% greater than that of an R-22 system.

    RDHolder
    shop.rdholder.com
    Thank YOU, i have been telling this to people and they just don't understand this. Over and over i have said when you replace a R22 with a 410 you may need re-size it because swapping out a 3ton r22 with a 3ton 410 will not operate the same in high temps.

  11. #24
    Join Date
    Aug 2012
    Location
    Toronto, Canada
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    81
    Quote Originally Posted by dlove View Post
    Thank YOU, i have been telling this to people and they just don't understand this. Over and over i have said when you replace a R22 with a 410 you may need re-size it because swapping out a 3ton r22 with a 3ton 410 will not operate the same in high temps.
    X2

    Also.. With the iformation you have given, i believe a PROPERLY designed water cooled system best suits ur application

  12. #25
    Join Date
    Apr 2008
    Posts
    155
    Quote Originally Posted by KB Cool View Post
    And here's a quick low budget more harm than good in the long run fix.

    http://www.gogreenitems.com/Cool_N_S...m_p/cnss-1.htm
    The vid shows water being pulled into the coils. (No replaceable evaporation pads to protect the coil and throw-away when they foul collecting all the minerals.
    Do they say what is in the water treatment canister?

  13. #26
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    Feb 2006
    Location
    Phoenix,AZ
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    2,843
    Quote Originally Posted by mixsit View Post
    The vid shows water being pulled into the coils. (No replaceable evaporation pads to protect the coil and throw-away when they foul collecting all the minerals.
    Do they say what is in the water treatment canister?
    Are you serious?

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