Freon Filling steps required??

Discussion in 'HVAC Heating & Cooling' started by shahnaimath, May 24, 2011.

  1. shahnaimath

    shahnaimath New Member

    Messages:
    25
    Location:
    Saudi Arabia
    Hi all....

    Can anyone here explain me how to fill freon in a AC unit...What are some of the basic steps that are to be noted while filling freon in the AC unit i.e. suction pressure and discharge pressure readings.

    Please help I want to learn as this is very important for me...Thanks:cool:
  2. DonL

    DonL Out of the Trades

    Messages:
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    Location:
    Houston, TX
    That would depend on the type of refrigerant that you are using, and the type of system you are filling.

    Also depends if you are adding refrigerant, or opening up a system, And need to recover the refrigerant.

    No easy answer to that broad of a question.

    Have a Great Day.

    DonL
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
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    It can get messy, and there are some big fines if you don't do it right. People go to school for awhile to learn how to do it right, so trying to learn here on a forum, just isn't really a viable method...there's too much to cover. There are some general prinicples, but the specifics of an individual unit also need to be taken into account.
  4. cacher_chick

    cacher_chick Test, Don't Guess!

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    Freon is a brand name which is owned by DuPont. It is being phased out in the U.S. due to environmental concerns.
  5. DonL

    DonL Out of the Trades

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    I think that outlawing Freon R12 originally, was just to make money.

    If the new stuff is so safe then why do you have to recover it ?

    Just another way to make the consumer pay more, I think.


    DonL
  6. cacher_chick

    cacher_chick Test, Don't Guess!

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    Location:
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    Actually the replacement for R-12 (R-134a) is more environmentally friendly than it's predecessor, but it's still clearly not good for the future of the planet. A replacement for the replacement will be coming out in the not-so-distant future. It's clearly not over yet.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    First, you need to draw approx. a 250 micron vacuum on the system to remove all air and non-condensibles which may have gotten in. Hold for a while, to make sure it doesn't creep up much, which would indicate a leak. If the system is empty, you have to weigh in approx. the amount of charge stated on the equipment data plate BEFORE starting the compressor.

    Once you are ready to run, you hook up your gauges. You don't charge just by observing suction and discharge pressures. Those are not a fixed number, but will vary with ambient and load. You MUST measure suction superheat ( if using an orifice inside) or liquid subcooling if the unit is a heatpump, or otherwise has a TXV on the inside unit. ONLY the superheat or subcool numbers will tell you if the system is operating correctly, or needs to have the charge adjusted.
  8. DonL

    DonL Out of the Trades

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    Location:
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    Cool Beans jimbo, Nicely put.

    You be the Man...
  9. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    I think the first step would be to get certified for refrigerant gases, since you cannot buy most of them without it. Cerification would cover reclamation, vacuum purging, refilling, superheat, etc.
  10. shahnaimath

    shahnaimath New Member

    Messages:
    25
    Location:
    Saudi Arabia
    @Jimbo

    Thanks for the tips...We have a pool heater which works on refrigeration cycle. It is totally similar to an AC unit. The standard suction and discharge pressure readings are 65 and 250 for it. I just need some basic steps for filling R22 if the gas level falls below the mentioned range.
  11. DonL

    DonL Out of the Trades

    Messages:
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    Location:
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    shahnaimath, do you need a Certification in your country to work on refrigeration systems ?

    "if the gas level falls below the mentioned range" then that would indicate a leak, and the leak should be found and repaired, before adding more R22.

    Have a great day.


    DonL
  12. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Unfortunately, hj, EPA certification does not cover any aspects of system maintenance or installation. It is strictly limited to the legalities of not allowing gas to escape, how to keep your log books, etc. Other than a contractor's license for the company owner, there is not any legal requirement ( here in CA at least) for licensure or training of HVAC techs. And there are plenty of shade tree operaors out there!
  13. shahnaimath

    shahnaimath New Member

    Messages:
    25
    Location:
    Saudi Arabia
    @DonL

    We dont really need any kind of certifications here for filling R22...

    Also there may be chances of gas evaporating and this should be one of the causes low pressure values..
    Last edited: May 25, 2011
  14. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Systems are completely closed, including the hermetic compressor. There is NO evaporation, even in your climate. If the charge is low, it is because there is a leak.
  15. Tom Sawyer

    Tom Sawyer In the Trades

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    Location:
    Maine
    Well all you EPA and code guys..... He's in Saudi Arabia, doubt that they give a flyin F what spilles into the air over there and even here, the EPA only harasses us licensed HVAC technicians. Homeowners can do any damn thing they want.
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